From AI Adoption to AI Governance - Using APIM as the Gateway for Azure AI Foundry
Co-authored by Gaurav Jain (Senior Cloud Solution Architect @ Microsoft) and Abhishek Mittal (Cloud Solution Architect @ Microsoft) Enterprises move through three phases of AI adoption: evaluating models, building apps and agents, and operationalizing them in production. The first two are easier to accelerate. The third is where governance becomes critical. Once multiple teams share an AI endpoint, leaders need clear answers to practical questions: which model consumed tokens, which team used them, and who is authorized to call it? This post shows how to place Azure API Management (APIM) in front of Azure AI Foundry as an AI Gateway, turning a shared endpoint into a governed control point for per-model token visibility, chargeback, and budget alerts — with no changes to client code. It also shows where Azure Front Door and Web Application Firewall (WAF) fit in a secure AI Landing Zone. The problem: AI adoption is outpacing AI governance A common starting point is an Azure OpenAI resource running multiple models. The team already has operational telemetry, but governance needs a different view: per-model token usage for chargeback, budget alerts, and capacity planning, captured in one place. Azure gives you rich resource-level telemetry out of the box, and that is exactly where we started: Azure Monitor — Metrics blade: shows token usage split by model and deployment in near real time. Diagnostic settings: stream the resource's metrics and request logs into Log Analytics (the AzureMetrics and AzureDiagnostics tables). Azure Monitor provides useful resource-level telemetry, including metrics and diagnostic logs. A governance view needs something different: model identity and token counts correlated in a single record, so teams can build a per-model, month-to-date ledger for chargeback and alerting. The AzureMetrics table carries the token totals, aggregated at the resource level. The AzureDiagnostics logs carry the model and deployment name at the request level. Each stream does its job well. Correlating them into one per-model, month-to-date ledger — and alerting on it — is a governance concern that sits above any single resource. Azure Monitor metric alerts, for instance, work on a rolling 24-hour window that maps cleanly onto a per-day token budget; a month-to-date, per-model chargeback ledger is simply a different shape of question — and a natural fit for a dedicated control point. This transition is the focus of this post: moving from AI adoption to AI governance by introducing a control point where model identity and token usage are captured together by design. The natural home for that control point is an AI gateway — and we build it next with Azure API Management in front of Azure AI Foundry. The pattern: APIM as the AI Gateway for Azure AI Foundry The AI gateway in Azure API Management is a set of capabilities to secure, scale, monitor, and govern the AI models, agents, and tools behind your apps. It isn't a separate product — it extends the existing API Management gateway. As Microsoft's guidance puts it, as AI adoption matures the gateway helps you authenticate and authorize access to AI services, load balance across endpoints, monitor and log AI interactions, and manage token usage and quotas across multiple applications. APIM becomes the governed front door for Azure AI Foundry. Clients continue calling an OpenAI-compatible endpoint; APIM authenticates to Foundry with a system-assigned managed identity, forwards the request, and emits per-model token telemetry to Azure Monitor and Application Insights. The result is per-model visibility without client-side changes. Models behind the gateway The gateway can front any model deployment in Azure AI Foundry — Azure OpenAI models, other Foundry models, or a mix — and the pattern is identical no matter which you run. For a concrete reference, the walkthrough in this post sits in front of two existing deployments: Deployment Model Provisioned capacity (TPM) gpt-4.1 gpt-4.1 500K gpt-5 gpt-5 50K Example deployments referenced throughout this post. Note the deliberate capacity gap — gpt-5 at 50K TPM versus 500K for gpt-4.1 — exactly the kind of asymmetry that makes per-model visibility a governance requirement, not a nice-to-have. Architecture Figure 1 — Architecture / component flow: consumers call one governed API; the inbound policy authenticates with a managed identity, resolves the model, and emits per-model token metrics to Azure Monitor and Application Insights. The starting point (“before”): a pass-through without a usage signal By default, APIM operates as a straightforward proxy. If you import a Foundry API and keep the default configuration, the policy simply selects the backend service: <policies> <inbound> <base /> <set-backend-service id="apim-generated-policy" backend-id="foundry-backend" /> </inbound> <backend><base /></backend> <outbound><base /></outbound> <on-error><base /></on-error> </policies> A plain pass-through API. It forwards traffic faithfully — it simply doesn't surface a usage signal yet. This is our “before.” Pass-through configuration works, but it does not distinguish traffic by model. All requests flow through the same stream, with no per-model chargeback signal, no capacity warning, and no clear view of which deployment is driving consumption. To govern the workload, the gateway must understand the traffic — not just relay it. The governed gateway (“after”): a policy that sees every token The custom inbound policy below is the heart of the pattern. It does four things in order: set-backend-service — select the Azure AI Foundry backend. authentication-managed-identity — obtain an Entra ID token for cognitiveservices.azure.com using the APIM system-assigned identity. No keys ever leave the gateway. set-variable deployment-id — resolve the model name from either the URL path or the request body (more on why below). azure-openai-emit-token-metric — emit prompt, completion, and total token counts to Azure Monitor, dimensioned by model. <policies> <inbound> <base /> <set-backend-service backend-id="foundry-backend" /> <authentication-managed-identity resource="https://cognitiveservices.azure.com" /> <!-- Resolve the model/deployment name. The Foundry Model Inference API (/models/chat/completions, /models/embeddings, /anthropic/v1/messages) passes it in the JSON body as "model". The Azure OpenAI-style surface (/openai/deployments/{name}/...) passes it in the URL path. Handle both. --> <set-variable name="deployment-id" value="@{ var path = context.Request.Url.Path ?? ""; var m = System.Text.RegularExpressions.Regex.Match(path, "/deployments/([^/?]+)"); if (m.Success) { return m.Groups[1].Value; } try { var body = context.Request.Body?.As<JObject>(preserveContent: true); var model = body?["model"]; if (model != null && !string.IsNullOrEmpty(model.ToString())) { return model.ToString(); } } catch (Exception) { } return "unknown"; }" /> <!-- Emit token-usage metrics dimensioned by model, so consumption can be sliced per model in Azure Monitor / Application Insights. --> <azure-openai-emit-token-metric namespace="genai-tokens"> <dimension name="ModelDeploymentName" value="@((string)context.Variables["deployment-id"])" /> <dimension name="ModelName" value="@((string)context.Variables["deployment-id"])" /> <dimension name="APIId" value="@(context.Api.Id)" /> <dimension name="Subscription" value="@(context.Subscription?.Id ?? "none")" /> <dimension name="Client IP" value="@(context.Request.IpAddress)" /> <dimension name="Product ID" value="@(context.Product?.Id ?? "none")" /> </azure-openai-emit-token-metric> </inbound> <backend> <base /> </backend> <outbound> <base /> </outbound> <on-error> <base /> </on-error> </policies> The full custom policy, applied at API scope. The highlighted value is the model-name resolution feeding a per-model token metric. Request flow, end to end Figure 2 traces a single chat request from top to bottom — from the caller, through the gateway's inbound policy, out to Azure AI Foundry, and into your telemetry. Figure 2 — Per-request flow: authentication, model resolution, forwarding, and token-metric emission. The request flow is straightforward: the client calls the APIM endpoint, the gateway selects the Foundry backend, authenticates with managed identity, resolves the model name, forwards the request, emits token metrics, and returns the response unchanged. Governance is added at the gateway without requiring client-side changes. Why dual-shape model resolution matters The azure-openai-emit-token-metric policy can emit usage, but it still needs a model dimension. Different API surfaces place the model name in different locations: Foundry Model Inference and Anthropic-style requests use the body, while Azure OpenAI-compatible calls use the URL path. The policy handles both shapes, so one gateway can govern all callers consistently. Observability: per-model token visibility and chargeback Metrics land in Azure Monitor / Application Insights under the namespace genai-tokens. The policy records Total Tokens, Prompt Tokens, and Completion Tokens, each tagged with Model Name, Model Deployment Name, API Id, APIM Product Subscription, Client IP, and Product ID. The data can then be queried directly. Per-model consumption over time: customMetrics | where name == "Total Tokens" | where timestamp >= startofmonth(now()) | extend ModelName = tostring(customDimensions["ModelName"]) | summarize TotalTokens = sum(valueSum), Calls = sum(valueCount) by ModelName Per-model token consumption (Application Insights customMetrics). And a per-model, per- API product subscription view for chargeback: customMetrics | where name == "Total Tokens" | where timestamp >= startofmonth(now()) | extend Model = tostring(customDimensions["ModelName"]), Sub = tostring(customDimensions["Subscription"]) | summarize Tokens = sum(value) by Model, Sub, name | order by Tokens desc Chargeback: tokens by model and consuming subscription. The gateway records model identity and token usage together, so the chargeback view is built in. The same signal supports dashboards, daily budget alerts, capacity planning, and cost allocation by subscription or product — without changing client code. Turning the signal into a Cost Guardrail: a 24-hour token alert Because the token totals now carry the model name, you can put a hard guardrail on spend. Wrap a query in an Azure Monitor log search alert rule that sums Total Tokens over the last 24 hours per model and returns only the deployments that breach a daily budget: // Rolling 24-hour token-budget guardrail — returns any model over its daily cap let dailyTokenBudget = 50000; // max Total Tokens per model in a rolling 24h window customMetrics | where name == "Total Tokens" | where timestamp > ago(24h) extend Model = tostring(customDimensions["ModelName"]) | summarize TokensLast24h = sum(value) by Model | where TokensLast24h > dailyTokenBudget | extend OverBudgetBy = TokensLast24h - dailyTokenBudget | project Model, TokensLast24h, DailyBudget = dailyTokenBudget, OverBudgetBy A rolling 24-hour token-budget check. The alert rule fires whenever this query returns one or more rows. Configure this as a scheduled log search alert: evaluate on a short cadence (for example, hourly over the trailing 24-hour window), set the alert logic to fire when the result count is greater than zero, and attach an action group that notifies the team through an email distribution list or Microsoft Teams channel. When any model crosses its rolling 24-hour token budget, the owning team is alerted, so overspend is detected within the day rather than at invoice time. Tune dailyTokenBudget per model, or add a single all-up cap, and translate token budgets into estimated daily cost ceilings to maintain continuous spend visibility. Completing the picture: securing the AI Landing Zone with Front Door + WAF APIM governs model usage; Azure Front Door with WAF governs public access. Placing WAF at the edge protects the AI endpoint from common web attacks, malicious bots, abusive callers, and unwanted source IP ranges before traffic reaches APIM or Foundry. What Front Door + WAF adds OWASP protection: The Azure-managed Microsoft_DefaultRuleSet_2.1 helps defend against OWASP Top 10 web attacks and known CVEs; Microsoft_BotManagerRuleSet_1.0 helps block malicious bots. Run the policy in prevention mode so offending requests are rejected with a 403, not just logged. IP restriction and rate limiting: Custom WAF rules restrict access to known IP ranges and throttle abusive callers before they reach APIM or Foundry. Global edge: Front Door terminates TLS at the edge and provides a single, DDoS-protected public entry point for the workload. Defense in depth across the landing zone Layered against the Azure AI Foundry landing zone baseline, the request path looks like this: Defense in depth: WAF at the edge, governance at the gateway, isolation on the network, Foundry reachable over a private endpoint. The baseline Azure AI Foundry landing zone reinforces every layer: private endpoints keep PaaS services (Foundry, Key Vault, Storage, AI Search) off the public internet; a system-assigned managed identity helps remove API keys; a hub-and-spoke topology routes egress through Azure Firewall; Azure Key Vault holds the Front Door TLS certificate; and Azure Policy enforces guardrails across the subscription. The gateway pattern from Sections 2–6 slots directly into this architecture as the governed control point for model traffic. Outcomes and what to extend next With APIM and the security edge in place, the shared endpoint supports per-model chargeback, capacity planning, zero client changes, and a stronger security baseline. The same gateway pattern can then be extended with token quotas, semantic caching, content safety, resiliency, and a unified model API (preview). Closing thoughts Moving from AI adoption to AI governance does not require re-architecting every app; it requires a control point. APIM in front of Azure AI Foundry provides that point: one policy turns token usage into a per-model governance signal, and Front Door with WAF provides a hardened edge. Start with visibility, then add quotas, safety, and resiliency as adoption scales. References AI gateway capabilities in Azure API Management — Microsoft Learn Baseline Microsoft Foundry Chat Reference Architecture in an Azure Landing Zone - Azure Architecture Center Protect Azure OpenAI using Azure Web Application Firewall on Azure Front Door — Microsoft Learn LLM token limit policy — Microsoft Learn Emit token consumption metrics (llm-emit-token-metric) — Microsoft LearnHow to build long-running MCP tools on Azure Functions
Recently, a customer building servers with the Azure Functions MCP extension reached out and asked: How do I handle tools that take longer than the client is willing to wait? This becomes especially relevant when tool calls move beyond simple request/response into multi-step workflows and long-running operations. At the same time, MCP is evolving to address exactly this. The Tasks extension is introduced in the 2026-07-28 release candidate, defining a standard way to model long-running work. In this post, we’ll walk through how to build long-running MCP tools on Azure Functions using Durable Functions , a framework for authoring stateful, long-running workflows as ordinary code, with checkpointing, scaling, and recovery handled automatically. MCP tools today Today, MCP tools are fundamentally request/response: the client issues a tools/call the server returns a result This works well for fast operations, but breaks down when: workflows take minutes execution depends on multiple steps latency is unpredictable In practice, clients enforce their own tool-call timeouts. These aren't standardized by the MCP spec and vary per client, but they're often in the ~30–60 second range. If a tool exceeds that window: In practice, clients often enforce short timeouts. If a tool exceeds that window: the client times out the agent observes a failed call the underlying work may still be running So the core issue is that you have synchronous tool calls don’t naturally model long-running work. The MCP Tasks extension The Tasks extension to address this. With the extension, a server can respond to a tools/call with an asynchronous task handle instead of a final result, and the client drives the lifecycle from there: tasks/get: poll the task's status tasks/update: submit input back to the server if the task reaches input_required tasks/cancel: cancel an in-flight task A task carries a status ("working", "input_required", "completed", "failed", or "cancelled") and on completion, the final result. Task creation is server-directed: the client advertises support by including the extension in its per-request capabilities, and the server decides per request whether to return a task. A server won't return a task to a client that hasn't advertised support. It's important to note that Tasks rely on ecosystem support. Clients must advertise the extension, and MCP SDKs must implement the task lifecycle, before servers can use it. So while Tasks is now a defined extension, broad client and SDK support is still in progress. Implement long-runng tasks with Durable Functions today Until the Tasks extension is broadly supported across clients, we need a pattern that works with existing request/response clients and supports long-running execution. The following samples show how, using Durable Functions: Python NET The long-running work in this sample mines a short chain of blocks. Each block requires solving a computational puzzle where the system keeps trying different inputs until it finds one that produces a result matching a specific pattern (for example, starting with a certain number of zeros). Because this involves lots of trial and error, it naturally takes time, making it a good example of a long-running workflow. The server in the sample exposes two tools: start_mining Starts a Durable Functions orchestration to mine the blocks Waits briefly (within a configurable budget) Returns result inline if completed within budget OR returns workflow_id if still running get_mining_result Takes the workflow_id Returns the current state, e.g. "completed", "running", "failed", or "not_found" To ensure that the agent calls the tools in the right order, workflow_id is a required parameter of get_mining_result, so the agent can't poll without starting a mining run first. Also, the "running" response carries a poll_after_seconds and a next instruction, ensuring the agent to poll again if work is not done rather than give up or assume completion. Even so, the poll path still relies on the agent correctly remembering, and not hallucinating, the workflow_id it was handed. If it garbles or invents an id, the poll lands on the wrong instance or none at all (which is why get_mining_result returns "not_found" rather than guessing). What changes with the Tasks extension Once the Tasks extension is fully implemented across clients and SDKs, the model becomes simpler and more reliable: the server returns a Task handle, the client manages the polling and lifecyle calls, and the SDK tracks execution state. This removes a key limitation of today’s solution, which requires the agent to remember and correctly pass identifiers like workflow_id. Call to action Try out the sample and let us know whether it addresses your MCP needs around long-running or workflow type tools!
How Many Copies of Each Layer Does Your Container Registry Actually Need?
Authors: Payal Mahesh and Vicky Lin Azure Container Registry team: Jeanine Burke and Johnson Shi Introduction It's Monday morning. You spin up a fresh 1,000-node AKS cluster for a big training run or a fleet-wide rollout. Every node reaches for the same large container image at the same instant. What actually happens in the next ten minutes - and whether your pods reach Ready in 9 minutes or 14 - turns out to depend on a single number you've probably never thought about: how many copies of each image layer exist behind your registry. At the surface, you see a single capacity number for your registry size - but behind that abstraction, Azure Container Registry maintains copies of your layer data to optimize pull performance. That number of copies directly determines the read throughput available per layer. Each copy can serve requests independently, so distributing the layer across storage allows it to be read in parallel. More copies mean more independent readers - and higher aggregate throughput when thousands of nodes pull at once. The intuitive answer is that more is better: add copies, get faster pulls. When we actually tested it at 1,000-node scale, the truth turned out to be more interesting: A few extra copies helped a little. A moderate number helped a lot, and eliminated storage throttling entirely. A large number helped no more than the moderate one. A huge number actually made pulls slower again. Think of it like opening checkout lanes at a grocery store. Opening a few more lanes when the store is slammed cuts the line dramatically. Past a certain point, though, extra lanes barely help, because by then it's the customers, not the cashiers, who are the bottleneck. And open too many? Now the staff is spread thin and tripping over each other, and the line moves worse than it did at the sweet spot. This post walks through what we measured, why the curve bends where it does, and what we're building next so finding that sweet spot isn't something anyone has to do by hand. Key Takeaways There's a sweet spot, not a slope. Adding copies per layer cut pod-startup P99 by 27% and raised P50 per-node egress throughput by 244%, but only up to a point. Past that, the returns vanish, and far past it, latency actually regresses. Storage throttling is the real enemy. The win comes from spreading load across enough storage backends that no single backend gets pinned at its egress ceiling. Once throttling is gone, more copies stop helping. Storage scale alone has a ceiling. Even at the sweet spot, the per-backend egress limit caps total throughput. The next jump in performance has to come from somewhere else, which is exactly what we're building (see What's Next). This isn't something customers should need to manage. We're building a proactive, on-demand storage scaling capability that automatically grows the footprint before throttling happens and shrinks it back when the burst is over. A quick bit of background Within a region, the layer data behind your container images is backed by Azure storage. The number of copies ACR maintains per layer determines how many independent storage backends a concurrent-pull workload can spread its reads across. That's what matters, because each backend has a finite egress ceiling. Once concurrent reads against one backend get close to that ceiling, requests start getting throttled, and your pulls slow down in proportion. The principle is simple: more copies per layer means more backends serving the same data, which means more total egress headroom and fewer throttled requests. What we wanted data on was how many, and where it stops helping. How we tested We ran a controlled series of large-scale pull tests against ACR Premium on a roughly 1,000-node cluster, with every node pulling the same large image cold at the same time (no local cache on any node). The only thing we changed between runs was the number of per-layer copies behind a single registry endpoint. Everything else, including rate limits, the image, node count, and concurrency, stayed constant. For each run we measured pod-startup latency (P50/P90/P99), end-to-end storage read latency, egress throughput distributions (P50-P99.9), and storage throttling events. Pod-startup latency is our headline metric, because it's the one number that reflects the actual customer experience no matter where the bottleneck happens to be. Per-node egress throughput matters too, though. It tells you directly how much pull bandwidth ACR delivers to your fleet, and it's usually what customers have in mind when they ask how much faster extra copies will make their pulls. We report egress as a distribution rather than a single average, since per-request and per-time-window views can tell very different stories about the same set of pulls. These are observations from a single controlled environment, not a service guarantee. Absolute numbers will move with image size, node count, layer composition, network topology, and concurrency. What we found We tested five configurations, sweeping from a low baseline number of per-layer copies up to a very high one. We name them by relative copy count rather than exact instance counts: Baseline: the lowest level, our reference point. Low: a modest step up from Baseline. Mid: a meaningful step up from Low. Higher: a further step up from Mid. Very high: the largest configuration we tested, well above Higher. Here are the numbers. All percent changes are relative to Baseline. Configuration Pod startup P50 Pod startup P90 Pod startup P99 Storage throttling events Peak per-backend egress Baseline (fewest copies) 9m 36s 11m 0s 14m 16s Many; all top backends above the egress ceiling Highest Low 9m 27s (−2%) 10m 14s (−7%) 12m 59s (−9%) Some; one backend still above the ceiling High Mid 9m 25s (−2%) 9m 45s (−11%) 10m 22s (−27%) Zero Below the ceiling Higher 9m 20s (−3%) 9m 37s (−13%) 10m 22s (−27%) Zero Well below the ceiling Very high 9m 28s (−1%) 10m 31s (−4%) 13m 48s (−3%) Zero Lowest Look at the P99 pod-startup column from top to bottom: 14m 16s, 12m 59s, 10m 22s, 10m 22s, 13m 48s. It improves, flattens out, then climbs back up. Three things explain that shape: 1. The win: Throttling falls off a cliff at the Mid configuration As we added copies per layer, per-backend egress fell and storage-side throttling decreased. At the Mid configuration, throttling errors hit zero, and they stayed at zero for every configuration above it. The upside isn't just that the errors went away, though. It's raw pull bandwidth. At the Mid sweet spot, the typical node saw its P50 egress throughput jump 244% over Baseline. With load spread across enough copies, each node pulled its layers off storage much faster, not just without stalling. For a workload owner, that's the difference between watching pods come up in a steady stream and watching them stall for tens of seconds at a time while throttling clears. Same image, same node count, same registry, very different experience. To put it in concrete terms: if your team runs a daily AI training kickoff that needs all 1,000 nodes pulling before the job can start, this is the difference between starting on time and starting four minutes late every day. Over a quarter of training runs, that adds up. 2. The surprise: more copies made pulls slower This is the finding that genuinely surprised us. Going from Higher to Very high, the largest configuration we tested, cost us 3 minutes and 26 seconds at P99: 10m 22s climbing back up to 13m 48s. That gave back almost the entire benefit we'd built up over the previous four configurations. Tail storage-read latency at Very high actually came out worse than Baseline. The Very high run is where the wheels came off, and the reason is the trade-off underneath. Once storage throttling is gone, more copies stop buying you anything, and the cost of fanning reads across that many backends starts to take over. The throughput distribution shows it clearly. P50 and P75 throughput had been climbing steadily and getting smoother through Mid and Higher, then dropped sharply at Very high while the peak P99/P99.9 spikes came back. Spread the same load across too many backends and it fragments into smaller, less consistent bursts. The takeaway is that "more is better" stops being true past the sweet spot, and the failure mode is quiet. You won't see throttling errors. You'll just see your pulls get slower. 3. What we didn't expect: at few copies, the hottest backend is what hurts you At the lowest copy counts, pull traffic wasn't spread evenly across the underlying storage footprint. Some backends absorbed far more traffic than others. As we added copies, that distribution evened out and the hottest backends cooled down. The implication is sharp. You can saturate the busiest backend, and trigger throttling, even when the total headroom across all your backends is large in aggregate. What matters is the load on the hottest backend, not the average. That's exactly the failure mode that demand-driven, proactive scaling (described below) is meant to head off before it happens. So how should you think about this? You don't size copies yourself; ACR manages the storage footprint behind your registry. Still, it helps to understand what moves the sweet spot, because the shape of your own workload is what decides where it lands. The bigger your worst-case concurrent burst (more nodes, larger images, higher concurrency), the more copies per layer it takes to keep pulls off the throttling ceiling, and the further out the sweet spot sits. Smaller workloads may already be sitting on the flat part of the curve. One thing is worth saying plainly. The storage footprint underneath is managed by ACR and shared across many registries, so there's no fixed, private storage budget that maps one-to-one to your workload. The sweet spot isn't a number you compute and provision; it's a behavior the platform has to land on for you, which is exactly why we're moving toward demand-driven scaling that handles it automatically. That's what brings us to what we're building next. What's next: proactive, on-demand storage scaling and a caching layer The fixed-copy tests above answer the question "how many should the ACR system provision?" but they assume a single, static answer. Real workloads aren't static. A 1,000-node burst happens at deploy time, not at 3 a.m. on a Tuesday. And no matter how many copies are provisioned, the per-backend storage ceiling still bounds peak deliverable throughput. So we're investing along two complementary directions. 1. Proactive, demand-driven storage scaling We're building a capability that adjusts the number of per-layer copies automatically based on real-time pull demand: Proactive, not reactive. The system scales the storage footprint before concurrent pull pressure pushes any single backend near the throttling threshold, so throttling is prevented before it forms rather than cleaned up after the fact. On-demand scale-out. The footprint expands automatically as sustained pull demand grows. Scale-in when demand subsides. The footprint contracts so you're not paying for steady-state capacity you only needed during a burst. Tiering for cold content. Long-tail, rarely-pulled content can sit on colder storage, so the redundant footprint of frequently-pulled content doesn't pay full hot-storage cost everywhere. The benefit to customers is straightforward: smoother pulls under burst, higher delivered throughput on average, no permanent over-provisioning, and no manual re-tuning as workloads grow. 2. A caching layer to absorb burst beyond the storage ceiling Even a perfectly scaled storage footprint runs into the per-backend egress ceiling at extreme scale. To push past it, we're investing in a caching layer in the registry service that absorbs burst traffic before it ever reaches storage. A pull surge that hits the same set of layers, which is the common case for fleet-wide deployments, can be served largely from cache. That takes a lot of load off any single storage backend and complements the storage scaling above. We'll share results from this work in follow-up posts. If you have questions about scaling ACR for your workload, or about how we measure storage performance, reach out on the Azure Container Registry GitHub repository. Note: All results in this post are based on controlled internal testing configurations and are intended to illustrate general scaling behavior rather than prescribe exact configurations.VNet integration for Azure SRE Agent (preview)
For many production systems, the logs, databases, private endpoints, repositories, and runbooks an SRE Agent needs to do its job are behind network boundaries your security team already governs. VNet integration for Azure SRE Agent, now in preview, puts the agent's outbound traffic under those same controls - your virtual network, your NSG rules, your private DNS - so it reaches only what your network allows. The principle is one your security team already applies to every other workload: a component's network access shouldn't depend on the component behaving correctly. Identity governs what the agent can reach. Permissions and hooks shape what it does within reach. The network sits beneath both: it blocks any request to a destination you haven't allowed no matter what the agent decides. Why egress control matters Two reasons. First, the agent reads sensitive things by design. Inspecting logs, code, configuration, and internal systems is the whole point during an incident, which means you have to decide where that data can go. Open egress gives that data a path out of your network - a risk you wouldn't accept for any other production-adjacent workload. Second, it reasons over text it didn't write - logs, issue descriptions, tool output — which is how prompt injection gets in. Handling that is partly model safety, and Azure SRE Agent runs under Microsoft's Responsible AI standard with safety work from OpenAI and Anthropic. Network controls add another layer: an instruction that tries to reach a destination you haven't allowed can't run, because the network blocks it. For example, an agent investigating an outage might query Log Analytics, read deployment configuration, and call an internal runbook - all private resources. With VNet integration, those calls follow the routes, DNS, and firewall rules your workloads already use. A request to an external endpoint you haven't allowed fails at the network boundary. It doesn't depend on the model recognizing the risk and refusing; the network stops it either way. Choose an egress mode Azure SRE Agent has three egress modes, and you don't have to start at the strongest. Unrestricted - all outbound traffic allowed Limited - deny all outbound, allow an explicit list of hosts. Gives you host-level control without setting up a full VNet Azure VNet - outbound traffic goes through a delegated subnet in your network, with your NSG rules and private DNS applied. The recommended mode for production and regulated workloads. How Azure VNet mode works Outbound traffic takes one of two paths, and every call takes exactly one. Your VNet. Everything not placed on the managed path goes through a delegated subnet in your own network, where your NSG rules, private DNS, and firewall all apply. The agent is just another workload on that subnet, so it can reach what the subnet can reach: databases behind private endpoints, internal services, monitoring stores, and key vaults -the parts of production that aren't reachable from the public internet. The resources that matter most during an incident are usually the private ones. If your network connects to on-premises over ExpressRoute or VPN, the agent can reach those systems too, as long as your existing routes and rules allow it. The managed infra path. Some destinations go through Azure SRE Agent's managed infrastructure network instead - platform services the agent needs, plus optional categories you turn on: package registries, code repositories, and remote MCP servers. This path skips your VNet, so your NSG rules and Firewall Policies don't apply to it. Treat it as a deliberate exception, used only where you need it. Why public services start on the managed path Public services are hard to allow by IP address. GitHub, PyPI, npm, NuGet, apt, and the container registries run on large, changing IP ranges, and they don't map to a single Azure service tag. If your NSG filters by IP and port, keeping those lists up to date is constant work, and when a list falls behind, the agent can't pull a package or read a repository - and an investigation stalls on a networking problem that has nothing to do with the incident. Each category has a toggle: package registries (PyPI, npm, NuGet, apt), code repositories (GitHub, GitHub Enterprise, Azure DevOps), remote MCP servers, and a list of additional hostnames. Starting with these on the managed path keeps the agent working reliably without maintaining an IP allowlist. For build-time dependencies, that's usually fine. If you want this traffic inspected too, the next step is name-based (FQDN) egress filtering in your own network. Once your firewall can allow github.com and pypi.org by name, you can move these categories off the managed path and route them through your VNet instead Configure it Two decisions: the subnet, and what (if anything) uses the bypass. Navigate to Settings > Workspace Configuration > Network Choose Azure VNet as the egress mode. Select a subnet that is /27 or larger and delegated to `Microsoft.App/environments`. Decide which categories, if any, use the bypass. Restrict who can change the egress mode and bypass toggles. These settings widen or narrow the agent's reach, so govern them like any production network control. Test the outbound behavior before using the agent with production data. A reasonable setup for most enterprises during preview: use Azure VNet mode, keep package registries and code repositories on the bypass if you need reliable access to them, and route everything else through your VNet. Stricter environments can turn those categories off and rely on their own name-based firewall rules. What it doesn't cover yet VNet integration is in preview, with two limitations to know. It covers outbound traffic only - reaching the agent privately from inside your network isn't part of this preview. And connector traffic still routes over the public internet; the governance and credential isolation in Connectors V2 still apply. Use VNet integration for outbound control of the agent workspace, and combine it with identity, RBAC, tool permissions, hooks, and connector governance for a complete set of controls. Where it fits VNet integration doesn't replace identity, RBAC, tool permissions, or connector governance. It controls where traffic can go. The agent still needs the right identity and permissions to access a resource in the first place. Identity is the foundation: your RBAC assignments decide what the agent can reach. Permissions and hooks shape what it does within reach: allow/ask/deny rules control what runs, and hooks let you inspect or change a tool call before it runs. VNet integration sits underneath, controlling where traffic can go no matter what the agent tries to do. You want the agent to be capable. You also want a boundary that holds whether or not it is. Get started Create an SRE Agent - https://aka.ms/sreagent Documentation - https://aka.ms/sreagent/newdocs Recipes - https://aka.ms/sreagent/recipes Build 2026 Announcement - https://aka.ms/Build26/blog/SREAgentIntroducing Azure Container Apps Sandboxes: Secure Infrastructure for Agentic Workloads
Today we are announcing the public preview of Azure Container Apps Sandboxes - a new first-class resource type that gives you fast, secure, ephemeral compute environments with built-in suspend and resume. This is the underlying infrastructure on which products like Cloud sandboxes in GitHub Copilot, Foundry Hosted Agents, and Azure Container Apps Express are built, you now have the opportunity to build your solutions leveraging this infrastructure. Azure Container Apps Sandboxes unlocks two massive opportunities. For platform developers and ISVs, sandboxes give you the same isolated compute fabric that powers many Microsoft products. You get the building blocks to create your own multi-tenant platform on proven, enterprise-scale infrastructure. For AI agents, sandboxes become a self-configurable tool that lets agents extend their own capabilities on the fly. An agent can spin up a fresh sandbox in milliseconds and use it to execute untrusted code, compile source, test HTTP requests against a live app, launch a browser session, or tackle whatever needs a quick and scalable infrastructure. On one side it empowers humans to build platforms, on the other it empowers agents to build their own capabilities. Both get enterprise-grade isolation, instant startup, and snapshot-based persistence out of the box. We'll walk through the resource model, sandbox lifecycle, the features that set Sandboxes apart - like snapshots, lifecycle policies, network egress controls, volumes, and managed identities - and show you how to get started with the portal and CLI. What Are Container Apps Sandboxes? Container Apps Sandboxes are secure, isolated compute environments that start in sub-second time, scale to thousands, and cost nothing when idle. Each sandbox runs in its own hardware-isolated microVM boundary - fully separated from the host, the platform, and every other sandbox. You bring your own Open Container Initiative (OCI) image, and Sandboxes handle the rest: provisioning from prewarmed pools, strong multi-tenant isolation, and snapshot-based suspend/resume that preserves full memory and disk state across sessions. There are many ways Sandboxes can help you build your next project - here are a few: Your own build & test systems - wire a Sandbox into your CI/CD flow to run builds while your laptop stays cool. Agents that can run anything safely - an agent spawns a sandbox, executes work inside it, and returns the output with no agent host privileges required. Agent swarms - decompose a research question, spawn N sandbox workers in parallel (each pinned to its own image and egress policy), and synthesize the result. Early access customers are already unlocking significant benefits by leveraging Azure Container Apps Sandboxes. "With Azure Container Apps sandboxes, SitecoreAI can safely enable agents to take real action. The combination of multi-tenant isolation, rapid scale-out, and full automation allows Sitecore to run long-lived, autonomous agents that securely execute code, manage workflows, and interact with enterprise systems within secure, governed environments. With this foundation, we can build agents that do real work: assembling content, personalizing experiences, and optimizing campaigns in production. Agents that operate continuously, learn from results, and improve over time, so our customers get better outcomes without giving up control." - Mo Cherif, VP of AI and Innovation, Sitecore "We got early access to Azure Container Apps Sandboxes, and got the first prototype integrated with Atlas AI in hours, and it's already shaping a new Atlas AI capability that we plan to launch in preview in Q3. It gives every Atlas AI agent a safe, sandboxed workspace (file system, terminal, code execution) on a customer's live data in Cognite Data Fusion. The value: Industrial process, reliability, and production engineers spend days and weeks on questions like "which wells are underperforming and why?" These questions are tractable but expensive, so they are asked rarely and decisions are made on gut feel. With this, an agent pulls the data, runs the analysis, cross-references maintenance and inspection records, and returns a cited draft in minutes. Sandboxes make it practical: Aligned feature set, per-customer isolation, pause/resume across multi-day investigations, scale-to-zero economics." - Kelvin Sundli, Product manager, Atlas AI, Cognite Resource Model: Sandbox Groups and Sandboxes The top-level ARM resource is Microsoft.App/SandboxGroups. A Sandbox Group is the management boundary for a collection of sandboxes that share configuration - think of it like a Container Apps Environment, but purpose-built for sandboxes. When you create a Sandbox Group, you specify: Subscription, Resource Group, and Region Sandbox defaults (optional): default CPU, memory, disk, max sandbox count, and default idle timeout Networking: optionally deploy into a custom VNet with a dedicated subnet for private networking Identity: System or user assigned Entra identity. Individual sandboxes are created within a Sandbox Group. Each sandbox has its own source (disk image or snapshot), resource tier, lifecycle policy, network egress policy, environment variables, ports, volumes, and connections. Sandbox Lifecycle Sandboxes have a well-defined lifecycle with the following states: State Description Creating Provisioning the sandbox from a disk image or snapshot Running Actively executing - backed by a live microVM Idle System-suspended after inactivity; can auto-resume on the next request Suspended Full state (memory + disk) preserved as a snapshot; no compute costs Resuming Restoring from a suspended or idle state - sub-second for most workloads Stopped User-initiated stop; can be resumed Stopping Graceful shutdown in progress Deleting Teardown in progress The key insight here is the distinction between Idle and Suspended. When a sandbox goes idle (e.g., no traffic for a configured timeout), the system can automatically suspend it and capture a snapshot. When a new request arrives, the sandbox resumes transparently. This gives you scale-to-zero economics with stateful compute - something that wasn't possible before without significant custom engineering. Disk Images: Bring Your Own Container Sandboxes boot from Disk Images - Open Container Initiative (OCI) images converted into an optimized root filesystem format. You point to any OCI image (public or private registry), and the platform builds a bootable disk image from it. You can start with public, pre-built images maintained by the platform (for example, Ubuntu base images), or bring your own private images. For private registries, you can authenticate with username/token or use a user-assigned managed identity for Azure Container Registry (ACR) – integrated with Azure as you expect. Snapshots: Full-State Persistence Snapshots capture the complete state of a running sandbox - memory, disk, and all running processes. When you resume a sandbox from a snapshot, every process, open file handle, and in-memory data structure is restored exactly as it was. A snapshot captures the full state of a running sandbox: memory pages, disk, processes. Two ways to make one - automatically on suspend, or manually on demand. Three things they're great for: Checkpointing mid-task so a long-running agent can resume exactly where it left off Cloning an environment that's already warm - dependencies installed, caches populated, services running Shipping a "ready-to-go" state that resumes in sub-second instead of cold-booting Snapshots are free during the preview, after which they will be stored as Azure Blob Storage at standard rates. Each snapshot records the source sandbox, resource allocation (CPU, memory, disk), and container metadata - so what you get back is exactly what you snapshotted. Resource Tiers Every sandbox is assigned to a resource tier that determines its CPU, memory, and disk allocation: Tier CPU Memory Disk XS 0.25 vCPU 0.5 GB 5 GB S 0.5 vCPU 1 GB 10 GB M (default) 1vCPU 2 GB 20 GB L 2 vCPU 4 GB 40 GB XL 4 vCPU 8 GB 80 GB When creating a sandbox from a snapshot, the resource tier is inherited from the snapshot and cannot be changed - this ensures the restored environment has the exact resources it was running with when the snapshot was taken. Lifecycle Policies: Auto-Suspend and Auto-Delete Every sandbox can be configured with lifecycle policies that automate state transitions and cleanup: Auto-Suspend Idle timeout: How long a sandbox can sit idle before being suspended (configurable: 1m, 2m, 5m, 10m, 30m, 60m) Suspend mode: Disk + Memory (default): Full snapshot including memory state - resume picks up exactly where you left off, with all processes and in-memory data intact. Disk: Only the disk is preserved; the VM restarts fresh on resume. Useful when you only need file persistence, not process continuity. Auto-Delete Automatically delete sandboxes after a configurable number of days of inactivity Prevents accumulation of abandoned sandboxes that consume snapshot storage These lifecycle policies are what make Sandboxes economically viable at scale. A platform serving thousands of tenants can configure aggressive idle timeouts (say, 60 seconds) with Memory suspend mode, and each tenant's sandbox disappears from the billing meter almost immediately - but resumes in sub-second time the moment they return. Network Egress Policy For scenarios involving untrusted code - AI agents executing LLM-generated scripts, multi-tenant SaaS with user-submitted workloads - controlling outbound network access is critical. Sandboxes provide a per-sandbox Network Egress Policy: Default action: Allow or Deny all outbound traffic Host rules: Domain-pattern rules (e.g., *.github.com → Allow) to permit specific destinations Custom CIDR rules: Network-level rules for IP ranges (e.g., 10.0.0.0/8 → Deny) Skip egress proxy: Option to bypass the egress proxy entirely when custom VNet routing handles policy enforcement This means you can run a sandbox in a deny-by-default posture and allowlist only the specific endpoints it needs (your API server, a package registry, etc.) - without setting up NSGs or firewall appliances. Managed Volumes: Persistent and Shared Storage Sandboxes support two types of mountable volumes, both managed by Microsoft: Volume Type Backed By Best For Managed Azure Blob Azure Blob Storage Shared data across sandboxes, file uploads/downloads, persistent artifacts Managed Data Disk Azure Disk Storage High-performance storage for databases, build caches, large working sets - only available to one sandbox at a time Blob volumes come with a built-in file explorer in the portal - you can browse, upload, download, create folders, and drag-and-drop files directly. Data Disk volumes provide dedicated block storage with configurable sizes. Secrets and Identity Secrets Sandbox Groups support key-value secrets scoped to the group. Secrets can be created, edited, and referenced by sandboxes within the group. These secrets can be used in egress policies to modify requests with transform or header-injection rules, without exposing the secrets to code running inside the sandbox. Managed Identity Sandbox Groups support both system-assigned and user-assigned managed identities, with full RBAC role assignment management. This means your sandboxes can authenticate to Azure services (Key Vault, Storage, Cosmos DB, etc.) without managing credentials - the same identity model you use everywhere else in Azure. MCP Connectors and Triggers ACA Sandboxes now supports managed connectors through the Model Context Protocol (MCP), giving sandboxes access to external APIs - including Microsoft 365, Salesforce, ServiceNow, GitHub, and 1,400+ other systems - without managing credentials directly. Attach a Connector Gateway to your sandbox group, and every sandbox in the group can call external APIs through a standardized MCP interface at runtime. Pair connectors with triggers to build event-driven automation: route an Outlook email to a sandbox that triages it with an AI agent, or react to a SharePoint file upload by extracting and processing the document all without writing glue code. Triggers can fire a shell command inside a sandbox or invoke an HTTP endpoint the sandbox exposes, so your automation shapes fit naturally around your workload. The integration is built on the new Connector Namespace service (az connector-namespace), the same runtime behind Logic Apps and Power Platform connectors, now available as a programmable layer for sandboxes. See the end-to-end samples for runnable azd up-deployable examples covering email triage and document automation scenarios. The Portal Experience Azure Container Apps Sandboxes are only available in the new Azure Container Apps portal that provides a rich, IDE-like experience for working with sandboxes. Creating a Sandbox The portal offers multiple creation paths: Standard Sandbox - full configuration control over source, resources, lifecycle, networking, and volumes GitHub Copilot Sandbox - preset, Copilot CLI ready to go, GitHub credentials can be wired through the Access Token before the sandbox is created Claude Sandbox - Claude CLI pre-installed, ready for agentic coding inside the sandbox Using Coding Agents (Copilot CLI / Claude Code) If you live inside Copilot CLI or Claude Code, you don't need to learn a new CLI. Install the azure-sandbox skill once and your agent picks up the right skills: # GitHub Copilot CLI # Add as a plugin marketplace /plugin marketplace add microsoft/azure-container-apps # Install all skills /plugin install sandboxes@Azure-Container-Apps # Claude Code claude plugin add microsoft/azure-container-apps The skill runs prerequisite checks silently (az --version, az account show, node --version, aca --version), prompts only if something's missing, and maps natural-language asks to the right aca commands. Bundled runbooks cover Copilot CLI BYOK (bring your own Azure OpenAI key), the deploy-a-web-app walkthrough, and shell setup. Sandbox Detail Page Once your sandbox is running, the detail page gives you immediate access to the sandbox terminal and additional details, such as - Network Audit - real-time egress traffic log showing allowed and denied requests Monitor - live CPU, memory, disk, and network utilization charts Connectors - attached connections with an "Add" action Volumes - mounted volumes with an "Add" action Log Stream - streaming container logs Processes - running process list inside the sandbox Files - file explorer to browse the sandbox filesystem The toolbar actions let you manage the state of the sandbox - Resume or Stop. In the Ellipsis menu (⁝) you can find additional settings to manage network Egress Policy and ingress (Add port), take a Snapshot of the sandbox, Commit (save disk state as a new disk image), set Lifecycle Policy or permanently Delete the sandbox. Finally, you can see additional Details in a side panel. Getting Started with the CLI and Python SDK All sandbox and sandbox-group operations go through the aca CLI. There are no az containerapp sandbox commands, - az is only used for az login, az account show, and resource-group management. Install (CLI) # Mac, Linux curl -fsSL https://aka.ms/aca-cli-install | sh # Windows irm https://aka.ms/aca-cli-install-ps | iex Run aca --help to get started. Install (Python SDK) pip install azure-containerapps-sandbox For more details, quick start and examples on ACA CLI and Python SDK, please go to https://sandboxes.azure.com Evolution from Dynamic Sessions If you've used Azure Container Apps Dynamic Sessions, Sandboxes are the next evolution of that capability. Everything Sessions can do, Sandboxes can do - and significantly more: Capability Dynamic Sessions Sandboxes Sub-second startup ✓ ✓ Strong isolation ✓ ✓ Custom container images ✓ ✓ Custom VNet integration ✓ (Partial) ✓ Suspend/resume with Memory and Disk snapshots - ✓ Lifecycle policies (auto-suspend, auto-delete) - ✓ Network egress policy (per-sandbox) - ✓ Persistent managed volumes (Blob, Data Disk) - ✓ Managed identity (system + user-assigned) - ✓ Secrets management - ✓ Configurable resource tiers - ✓ Direct access to sandbox in Portal experience - ✓ We will continue to support Dynamic Sessions, but all new investment goes into Sandboxes. If you're building new workloads on isolated ephemeral compute, start with Sandboxes. How It All Fits Together ACA Sandboxes is a platform primitive. It's the foundation on which multiple Microsoft products are already built - including ACA Express, Cloud sandboxes in GitHub Copilot, and Foundry Hosted Agents. When you build on Sandboxes, you're building on the same infrastructure that powers Microsoft's own portfolio. This is the evolution of what we shared with Project Legion in 2024. Legion described the internal infrastructure; Sandboxes exposes it as a customer-facing primitive that you can use directly. What's Next • Deeper Azure integrations - first-class connectivity with Azure networking, identity, storage, and AI services • Enhanced SDK and CLI - richer programmatic experiences for managing sandboxes at scale • More Microsoft services built on Sandboxes - this is just the beginning Get Started Today • Portal: https://sandboxes.azure.com/ • Documentation: Azure Container Apps Sandboxes • Pricing: Azure Container Apps Pricing (per-second vCPU/memory billing, scale-to-zero, snapshots at Blob Storage rates) We'd love to hear your feedback. You can ask questions, or file issues on the Azure Container Apps GitHub (prefix with [Sandbox] for Sandboxes-specific issues).Shaping what Azure SRE Agent does: Tool Permissions and Hooks
When an AI agent runs against production, the first question every security team asks is "What can it do, who decided it could, and what stops it from doing something it should not." Azure SRE Agent reached general availability in March. Since then, teams inside Microsoft and customers running it against real production workloads have asked for the same thing: finer-grained controls over what the agent can do on its own and a clear answer to who governs each call that reaches a tool. Today at Build 2026, we are releasing global tool access policies as one of a set of new governance controls. This post covers how they work. Tool access policies give security and platform teams a single place to define which tools the agent can invoke, under what conditions, and what requires human approval before it runs. Underneath those policies sits the identity the agent runs as the bedrock that every other control layer depends on. It is defense in depth applied to agent behavior: layers of control, each one holding on its own, so that governing the agent is something you can read, audit, and reason about as you scale it across production. Identity is the bedrock: managed identity today, agent identity next Start here, because nothing else matters if you skip it. The identity the SRE Agent runs as, and the Azure RBAC role assignments on that identity, are the most powerful boundary the agent works inside of. If your role assignments do not grant the agent access to a resource, none of the controls below come into play, because the agent cannot reach the resource to begin with. Network rules, tool permissions, hooks, and connector contracts all sit on top of an RBAC story that you write. The features in this post add layers above that floor. They do not replace it. Today the SRE Agent operates as a managed identity, and your RBAC role assignments on that identity govern what it can do. This is the bedrock, and it is the same model your other Azure workloads already use. You assign roles, you scope them, and the agent inherits exactly what you granted and nothing more. Everything that follows assumes the bedrock is in place. With identity settled, the next question is the obvious one: where is the agent allowed to send its traffic? Permissions: govern what the agent does with a tool Identity decides what the agent can reach. Permissions decide what the agent does with the access it has, down to the individual tool. Two levels cover the range: a point-and-click grid for the common cases, and hooks when a decision needs your own code. The grid is the easy mode. Every tool the agent can use, built-in tools along with MCP servers, services, and custom tools, shows up in one searchable list with two switches. On/Off sets whether the tool is available at all; turn it off and the agent cannot use it. Allow/Ask sets what happens when it is on: Allow lets the agent run the tool automatically, Ask requires a human to approve every time, except in Autonomous mode. Select tools in bulk to flip a whole category at once, filter by category or permission, and use the Advanced permissions tab when you want rules that apply at global, per-agent, or per-thread scope instead of tool by tool. Defaults stay put until you touch them, and the engine is fail-closed: if a rule cannot be evaluated, the call is blocked rather than allowed. That covers most of what teams need. Underneath those switches are three rules, allow, ask, and deny, and the Advanced tab is where you set them by scope. Global rules apply to every agent and thread, Agent rules to one custom agent, Thread rules to a single conversation. Deny is the hard one: it blocks the tool outright no matter the run mode, and a deny at a higher scope always wins, so an Allow at thread scope cannot reopen something denied globally. That split is deliberate. A platform team sets the Global guardrails that should never be crossed and the Asks that always need a human, and service teams add their own Allow rules at Agent scope for routine work, without being able to override the guardrails above them. Platform team, Global scope: deny: bash(az * delete *) - never delete, on any agent or thread deny: bash(kubectl delete *) ask: bash(az webapp restart *) - always confirm, even in Autonomous allow: bash(az monitor *) - auto-approve monitoring queries Service team, Agent scope: allow: bash(kubectl get *) - routine read-only work allow: bash(kubectl describe *) Two details make this safe to lean on. Rules match the canonicalized tool invocation rather than the raw text, so enforcement holds no matter how the command was assembled. And fail-closed has a softer edge than a hard stop: a cached last-known-good policy covers transient failures, so a blip in the policy store blocks the call rather than silently widening access. You can find these under Capabilities > Tools missions. The layer worth spending time on is hooks. Allow and Ask answer "should this tool run." Hooks answer "should this specific call run, given exactly what it is about to do." A hook fires before the agent runs a tool and receives the actual call, parameters and all. Your code then decides the outcome and can reshape it: rewrite parameters before they are sent, inject extra context into the pipeline as a user message so the agent reconsiders before its next step, block the call outright, or redirect the agent toward a safer path. Because your code sees the real parameters, the decision can depend on anything you can express in code: which resource the call targets, whether a value falls outside an allowed range, the time of day, the result of an external policy lookup. This is where you write the rule the grid cannot. Two kinds of hook, mixable on the same agent. Command hooks are a script you write; reach for these when code is enough. Prompt hooks put a separate LLM in the loop as a judge that evaluates the call in context; reach for these when the decision needs reasoning rather than a fixed rule. A real example from our own internal test agent: when the agent tries to list files through the shell with ls or dir, a hook blocks the call. The agent absorbs the signal, reconsiders, and reaches for the ListDir tool instead. The hook did not argue with a human. It shaped what happened next. As with the grid, configure nothing and the agent behaves exactly as it does today. Both are additive. Authoring one is a short form. You name the hook, pick the event (Pre Tool Use, so it runs before the call), and set a tool matcher, either picked from the tool menu or written as a regex like (FetchWebpage|SearchMemory) with anchors and lookaheads when you need them, so the hook fires only on the calls you care about. You set a timeout and a fail mode (Block, so a hook that errors or hangs stops the call rather than waving it through), and you write the body in Bash or Python. A command hook reads the call as JSON on stdin, the event name, the tool name, its parameters, and the call id, and answers on stdout. Print nothing and exit zero to allow. Return a block decision with a reason to stop the call, and that reason is what the agent reads back. You can also substitute: run a cheaper or safer version yourself, block the real call, and hand your own output back as the result, so the agent never runs the expensive or risky original. #!/bin/bash input=$(cat) tool=$(echo "$input" | jq -r '.tool_name') # Block one tool, with a reason the agent will read if [ "$tool" = "ExampleToolName" ]; then echo '{"decision":"block","reason":"Blocked ExampleToolName by hook policy."}' exit 0 fi # Otherwise allow: print nothing and exit 0 exit 0 You can find these under Builder > Hooks Each layer holds on its own The layers stack. Identity is the floor: your RBAC assignments decide what the agent can reach at all. Permissions, the grid and hooks together, decide what it does with a tool. You author each layer, each one holds whether or not the layer above it behaves as expected, and all of it configures through the same ARM and Bicep surface your platform team already uses, reproducible the way the rest of your Azure estate is. The upgrade path is additive and non-breaking. Existing agents keep working. Turn on each control when you are ready, in the order your governance requires. There is more coming. We run Azure SRE Agent inside Microsoft on our own production workloads, so we feel the same gaps you do, and the next round is shaped by what we hear from teams running it in production today. Which control is doing the most for you, and which one are you still waiting on? Let us know and thank you! Getting started Create new SRE Agent — https://aka.ms/sreagent SRE Agent Documentation — https://aka.ms/sreagent/newdocs SRE Agent recipes — https://aka.ms/sreagent/recipes Build 2026 Announcement - https://aka.ms/Build26/blog/SREAgentDesigning for High Availability: The Operational Reference for Running a Geo-Replicated ACR
By Johnson Shi, Zoey (Zhuyu) Li, Huangli Wu Introduction Three of the most common questions we hear from enterprise teams running geo-replicated Azure Container Registries (ACR) are: "How do I control which region serves my traffic?" — When my AKS clusters are spread across regions, can I pin each one to its co-located replica, or am I stuck with however the global endpoint routes? "What happens during a regional incident — is failover automatic or do I have to act?" — If the registry in one region degrades, does the global endpoint reroute on its own, or do I need to manually disable the affected replica? "What happens after the region recovers — does traffic return on its own?" — Is there a cooldown, a quarantine, or any manual step before failback? We answer those head-on, then go deeper on the operational details that come up when you actually run a geo-replicated registry: authentication across endpoint switches, throttling under load concentration, eventual-consistency failure modes, home region outage scope, webhooks, and private endpoint interaction. We draw on the official geo-replication docs, the global endpoint health-aware failover blog, the regional endpoints engineering design implementation, the regional endpoints public preview and private preview announcements, and the ACR reference for various registry endpoints, . This post also draws notes from the ACR product team on roadmap items that aren't yet documented elsewhere. Key Takeaways Health-aware failover is automatic. When the registry in a region degrades, the global endpoint reroutes away from it on the order of minutes, evaluated per-registry. No customer action required. Failback is automatic too. Once health-aware failover marks a region healthy again, the global endpoint resumes routing to it. There is no cooldown period. Health-aware failover applies only to global endpoint operations. It does not apply to regional endpoints (you're talking to one replica, period) or to dedicated data endpoints (the redirect is per-region). Health-aware failover is not triggered by throttling. It responds to regional ACR service health and Azure infrastructure health, not HTTP 429 responses. Use regional endpoints to manage per-replica throttling. Regional endpoints (Step 2a) give you explicit per-region URLs for workloads that need affinity, capacity planning, push/pull consistency, troubleshooting, or client-side failover. Use myregistry.<region>.geo.azurecr.io . Regional endpoints are available on Premium SKU registries. For workloads that don't need pinning, do nothing (Step 2b). The global endpoint plus health-aware failover handles routing automatically. Re-authenticate when switching endpoints. Each global or regional endpoint is its own authenticated surface; re-auth via az acr login , SDK auth, or the Kubernetes ACR credential provider on endpoint change. Don't run a long-lived DNS cache for the global endpoint. ACR purges DNS server-side on disable and during failover; a long-lived client cache works against that. For production workloads, enable dedicated data endpoints for security and DNS predictability on layer downloads. ACR is working on bounded staleness consistency for cross-replica eventual-consistency failure modes; see the FAQ. Background What is ACR geo-replication? Geo-replication is a Premium SKU feature that turns a single ACR registry into a multi-region, multi-write service. Every geo-replica in every region is writable — you can push, pull, and delete from any of them — and content syncs asynchronously between replicas under an eventual consistency model. Per-push replication time scales with the size and number of images being pushed. Similarly, when creating a new geo-replica, the time to populate the new geo-replica scales with the total size of the registry. A geo-replicated registry exposes a global endpoint at myregistry.azurecr.io . Behind that endpoint, ACR uses an internal traffic manager to direct each request to the replica with the best network performance profile for the caller — usually the closest replica, but not always. When clients are equidistant from multiple replicas, or when the closest replica is experiencing Azure infrastructure degradation, requests may be routed elsewhere. A geo-replicated registry also exposes a regional endpoint at myregistry.<region>.geo.azurecr.io , which allows clients to pin API requests to a specific geo-replica in lieu of global endpoints, which has Azure-managed routing among geo-replicas. Zone redundancy is always enabled for geo-replicas in regions where Azure has multiple availability zones — in those regions, ACR automatically spreads replica data across multiple availability zones within each region to protect against zonal outages. Endpoints and data endpoints: what goes where A common point of confusion: when you push or pull, not every request goes to the same place. The registry endpoints (global endpoint and regional endpoints), as well as the data endpoint, do different jobs. Your choice of data endpoint configuration has real consequences for security and resilience. Two kinds of traffic flow during a typical pull: Registry API traffic — authentication, manifest reads/writes, tag resolution, referrers, repository operations, blob location lookups, listing, metadata. This is everything except the actual layer (blob) bytes. All these API requests go to the global endpoint ( myregistry.azurecr.io ) or, if you've pinned your clients to call these APIs to a specific geo-replica, a geo-replica's regional endpoint ( myregistry.<region>.geo.azurecr.io ). Behind the scenes, the global endpoint internally proxies these requests to a specific geo-replica. Layer (blob) downloads — when the client asks for a blob, the registry doesn't serve the bytes itself. It returns an HTTP 307 redirect to a regional data endpoint (separate endpoint from the global endpoint or regional endpoints), and the client follows the redirect to download the layer from that region. Where that 307 sends you depends on whether you've enabled the registry's dedicated data endpoints feature: Configuration Layer downloads redirect to Default (no dedicated data endpoints) *.blob.core.windows.net (the underlying Azure storage account) Dedicated data endpoints enabled myregistry.<region>.data.azurecr.io for the region you were routed to Private endpoints enabled myregistry.<region>.data.azurecr.io for the region you were routed to Regional by design. Dedicated data endpoints always land you on a specific geo-replica's data endpoint — there is no "global data endpoint." With the global endpoint as your registry endpoint, the 307 redirect picks the data endpoint for whichever region the global endpoint chose to serve you. With a regional endpoint pinned to a specific region, the 307 always redirects you to that same region's data endpoint — never cross-region. Why dedicated data endpoints matter. Dedicated data endpoints are a Premium SKU feature that exists primarily to address security and firewall scoping. By default, layer downloads redirect to *.blob.core.windows.net — a wildcard storage FQDN. Firewall rules to allow that wildcard either let all Azure storage accounts through or none of them, which raises data exfiltration concerns and isn't tightly scoped to your registry. Dedicated data endpoints replace the wildcard with a fully qualified domain in your registry's own domain — myregistry.<region>.data.azurecr.io — so firewall rules can be scoped tightly to your specific registry, in your specific regions. That same design choice can also make layer downloads more predictable during routing changes. With dedicated data endpoints, the data endpoint FQDN is known ahead of time and lives in the registry's domain — one predictable hostname per region, configured once. Without them, the layer download has to resolve a wildcard storage FQDN that points to whichever storage account the registry happens to have provisioned, which is a separate DNS resolution path with its own routing behavior and its own caching profile. Dedicated data endpoints simplify the DNS picture by aligning the data path with the registry path and keeping the entire pull experience inside one set of predictable, scoped FQDNs. For any geo-replicated registry where security and high availability matter, enable dedicated data endpoints. Note: Health-aware failover applies only to operations against the global endpoint, not to regional endpoints or dedicated data endpoints. Take note that health-aware failover only kicks in and directs traffic away from a geo-replica when an Azure region is experiencing significant infrastructure degradation. At this stage, it does not kick in to redirect traffic to another geo-replica if a client's data plane API requests are throttled. See the relevant section below for the full scope when health-aware auto failover kicks in or not. The three traffic control tools ACR geo-replication gives you three complementary tools for controlling where traffic lands. Each one solves a different class of problem, and customers most often run into trouble when they reach for the wrong one. We name them up front and use these names throughout the post: Tool Who controls it What it does Use cases Health-aware failover Platform (automatic) Reroutes the global endpoint away from a region whose registry can't reliably serve requests Regional incidents, automatic recovery Replica enable/disable for global routing Customer (manual) Excludes a specific replica from global endpoint routing without deleting it; data continues syncing DR rehearsals, planned maintenance, quarantining a replica without losing it Regional endpoints Customer (per request) Dedicated per-region URLs ( myregistry.<region>.geo.azurecr.io ) that bypass the internal traffic manager entirely Pinning AKS clusters to co-located replicas, push/pull consistency, capacity planning, troubleshooting, client-side failover Health-aware failover and replica enable/disable both act on the global endpoint. Regional endpoints are a separate URL surface that coexists with the global endpoint — enabling them does not disable the global endpoint myregistry.azurecr.io . You can use both simultaneously and choose per workload. The behavior in question When the registry in one region experiences a real degradation, there are three possible answers to "what happens?": (A) Nothing automatic. The customer must manually disable the affected region's endpoint to stop traffic from being routed there. (B) The system detects the regional front-door failure and reroutes within seconds. (C) A per-registry health evaluation detects the degradation and reroutes the global endpoint within minutes, with no customer action. After the region recovers, routing resumes automatically. The answer today is (C). Before health-aware failover, customers were stuck closer to (A) — the system could see whether the regional reverse proxy responded, but not whether the registry could actually serve real pull and push traffic end to end. Health-aware failover closes that gap. We walk through all three tools in the next section, in order: setting up geo-replication, using regional endpoints to pin specific workloads, keeping the global endpoint for everything else, the manual replica disable mechanism, re-enabling participation in global routing, and what to expect when health-aware failover triggers. Walkthrough The following steps assume an existing Premium SKU registry and the Azure CLI logged in. We use myregistry as the registry name, myrg as the resource group, and eastus as the home region. Substitute <your-registry> , <your-rg> , and <your-region> for your environment. Prerequisites A Premium SKU ACR registry (geo-replication requires Premium) Azure CLI ( az ) installed and logged in For regional endpoints (Step 2a): Azure CLI 2.86.0 or later. All regional endpoints commands ( --regional-endpoints , az acr show-endpoints , az acr login --endpoint ) are available natively in Azure CLI 2.86.0+. If you previously installed the acrregionalendpoint private preview CLI extension, uninstall it with az extension remove --name acrregionalendpoint to prevent conflicts with the built-in CLI commands. Step 1: Add a West US replica to a registry that lives in East US Geo-replication requires the Premium SKU. The create call below fails on Basic or Standard. # Confirm the registry is Premium az acr show --name myregistry --resource-group myrg \ --query sku.name --output tsv # Premium # Create a West US geo-replica az acr replication create --registry myregistry --location westus # Confirm both replicas are present az acr replication list --registry myregistry --output table NAME LOCATION PROVISIONING STATE STATUS REGION ENDPOINT ENABLED ------ ---------- -------------------- -------- ----------------------- eastus eastus Succeeded online True westus westus Succeeded online True Pushes and pulls continue working through the existing replica throughout initial sync. Because the registry is multi-region, multi-write, the existing replica keeps serving traffic while the new replica catches up in the background. Initial replica seeding time is a function of registry size — the total number and cumulative size of images already in the registry that need to be replicated to the new replica — not the size of any single image. Step 2a: Pin workloads to specific regions using regional endpoints Use regional endpoints when a workload needs explicit per-region control. The five common cases: Regional affinity — an AKS cluster in East US should pull from the East US replica, every time, without ever hopping to a more distant replica because of a network performance fluctuation. Predictable routing — workloads that need to know exactly which replica will serve them, for benchmarking, capacity planning, or in-region traffic SLAs. Push/pull consistency — pinning both ends of a publish-then-deploy flow to the same replica eliminates eventual-consistency races. Troubleshooting — reproducing an issue on a specific replica requires sending traffic to that specific replica. Client-side failover — customers with their own health checks and business rules want to implement failover on their own terms, on signals only they can see. Enable regional endpoints on the registry: az acr update -n myregistry -g myrg --regional-endpoints enabled When enabled, ACR automatically creates per-region login server URLs for every existing geo-replica. No per-region configuration is needed. Note: Regional endpoints can be enabled on any Premium SKU registry, even without geo-replication. A registry without geo-replication has a single geo-replica in the home region, which gets one regional endpoint URL. However, the feature is most useful when your registry has at least two geo-replicas, where you can pin different workloads to different replicas for routing control and capacity distribution. Push to a specific region using its regional endpoint: # Log in to the West US regional endpoint az acr login --name myregistry --endpoint westus # Tag and push using the regional endpoint URL docker tag myapp:v1 myregistry.westus.geo.azurecr.io/myapp:v1 docker push myregistry.westus.geo.azurecr.io/myapp:v1 Pin AKS deployments to their co-located replica by using regional endpoint URLs in the deployment manifest. The example below shows two clusters in different regions; each cluster references the regional endpoint for its own region's replica (assuming replicas exist in both eastus and westeurope ): # East US-based AKS cluster pulls from the East US replica apiVersion: apps/v1 kind: Deployment metadata: name: myapp-eastus spec: template: spec: containers: - name: myapp image: myregistry.eastus.geo.azurecr.io/myapp:v1 --- # West Europe-based AKS cluster pulls from the West Europe replica apiVersion: apps/v1 kind: Deployment metadata: name: myapp-westeurope spec: template: spec: containers: - name: myapp image: myregistry.westeurope.geo.azurecr.io/myapp:v1 This eliminates cross-region pulls when global routing would otherwise prefer a different replica for a given client, and it gives you a per-region traffic profile you can plan capacity against. Regional endpoint operational tips View all endpoints. Use az acr show-endpoints to see all endpoint URLs for your registry — global, regional (if enabled), and dedicated data endpoints (if enabled): az acr show-endpoints --name myregistry --resource-group myrg Import from a specific geo-replica. When importing images between registries, you can use a regional endpoint to import from a specific geo-replica of the source registry. This is useful when you want predictable network paths or need to import from a replica in a specific region: az acr import \ --name mydownstreamregistry \ --source myupstreamregistry.westeurope.geo.azurecr.io/myapp:v1 \ --image myapp:v1 Firewall rules for regional endpoints. If you use firewall rules, allow access to the following endpoints for each geo-replica that clients connect to: Endpoint Purpose myregistry.<region>.geo.azurecr.io Regional endpoint for registry operations myregistry.azurecr.io Global endpoint (if also used) myregistry.<region>.data.azurecr.io Layer downloads (if using private endpoints or dedicated data endpoints) *.blob.core.windows.net Layer downloads (if not using private endpoints or dedicated data endpoints) For the full list of endpoint types and FQDN patterns, see the ACR reference for various registry endpoints. DNS-based routing without changing manifests. If you don't want to maintain different deployment manifests per region, you can keep all manifests pointing to the global endpoint ( myregistry.azurecr.io ) and use software-defined networking or a regional traffic manager to resolve the global endpoint to the appropriate regional endpoint based on the originating region's traffic. This achieves the same co-location goals as regional endpoints — predictable routing and reduced latency — without embedding region-specific URLs in your deployment manifests. Step 2b: Keep using the global endpoint for everything else For workloads that don't need explicit pinning, do nothing. The global endpoint at myregistry.azurecr.io continues to work exactly as before, and the global endpoint plus health-aware failover gives you intelligent routing across replicas without configuration. ACR picks the best replica for each client based on network performance and reroutes during regional incidents. Regional endpoints coexist with the global endpoint — enabling them does not disable myregistry.azurecr.io . You can use both simultaneously and choose per workload, mixing pinned workloads (Step 2a) with workloads that ride the global endpoint (Step 2b) in the same registry. Step 3: Take a replica out of global endpoint routing Use this when you need to keep a replica alive but stop it from serving global-endpoint traffic — for DR rehearsals, planned maintenance, or troubleshooting an isolated replica. # Exclude the West US replica from global endpoint routing az acr replication update --registry myregistry --name westus \ --global-endpoint-routing false Confirm the change: az acr replication list --registry myregistry --output table NAME LOCATION PROVISIONING STATE STATUS REGION ENDPOINT ENABLED ------ ---------- -------------------- -------- ----------------------- eastus eastus Succeeded online True westus westus Succeeded online False Requests to myregistry.azurecr.io no longer route to West US. The replica still receives replicated content — and continues to replicate its own content out to other replicas — and storage quota and per-replica costs continue to accrue. If regional endpoints are enabled, the West US regional endpoint URL also continues to work; --global-endpoint-routing controls only the replica's participation in global endpoint routing. A note on naming. The CLI flag --global-endpoint-routing (on az acr replication update ) and the regional endpoints feature (enabled via az acr update --regional-endpoints enabled ) are two different things despite the similar names. --global-endpoint-routing controls whether a replica participates in global endpoint routing. The regional endpoints feature creates per-region URLs ( myregistry.<region>.geo.azurecr.io ) that bypass the global endpoint entirely. They are independent controls. In Azure CLI 2.86.0 and later, the old --region-endpoint-enabled flag has been renamed to --global-endpoint-routing . The old flag name is deprecated and will be removed in Azure CLI 2.87.0 (June 2026). If you have existing scripts or automation that use --region-endpoint-enabled , update them to use --global-endpoint-routing . CLI flags quick reference: Flag Scope Purpose --regional-endpoints Registry-level ( az acr create or az acr update ) Enables dedicated regional endpoint URLs ( myregistry.<region>.geo.azurecr.io ) for all geo-replicas. --global-endpoint-routing Per-geo-replica ( az acr replication create or az acr replication update ) Controls whether the global endpoint routes traffic to a specific geo-replica. Set to false to temporarily exclude a geo-replica from global routing. --data-endpoint-enabled Registry-level ( az acr create or az acr update ) Enables dedicated data endpoints ( myregistry.<region>.data.azurecr.io ) for layer blob downloads. Auto-enabled when at least one private endpoint is configured. This bidirectional sync during disable is intentional. When you re-enable the replica, every image pushed to the registry while the replica was disabled — from any region — is already present, so the replica can serve traffic immediately with no catch-up window. If we stopped syncing on disable, re-enabling would leave the replica with stale data and force a long catch-up before it could safely serve pulls. Step 4: Re-enable the replica to participate in global endpoint routing Re-enable the replica: az acr replication update --registry myregistry --name westus \ --global-endpoint-routing true NAME LOCATION PROVISIONING STATE STATUS REGION ENDPOINT ENABLED ------ ---------- -------------------- -------- ----------------------- eastus eastus Succeeded online True westus westus Succeeded online True There is no cooldown. The global endpoint resumes routing requests to the West US replica as soon as the change takes effect on ACR's side. Because data continued syncing while the replica was disabled (Step 3), the replica is immediately ready to serve pulls — no catch-up window. Note on DNS during disable/enable. When you take a replica out of global routing, ACR purges its own DNS records for that replica from the global endpoint on a fast path — there is no waiting on a published TTL on ACR's side. If clients run their own DNS cache for the global endpoint, however, those clients will keep resolving to the disabled replica until the client cache expires. We can't control client-side caches. The recommendation: do not run a long-lived DNS cache for the global endpoint. A short-lived DNS pin for the duration of a single push (covered in the DNS and Client-Side Considerations section) is fine and even helpful — but a long-lived DNS cache will make --global-endpoint-routing false look broken from the client's perspective. Step 5: What to expect when health-aware failover triggers Health-aware failover is automatic. ACR evaluates registry health on a per-registry basis, and when a registry in a region can't reliably serve requests, the global endpoint reroutes that registry's traffic to a healthy replica. There is no customer-invocable trigger — that's the point. End-to-end timing is on the order of minutes — fast enough to catch real regional degradation, slow enough to ride out transient errors that resolve on their own. DNS TTL may add additional propagation delay before all clients switch to the new region. Scope of health-aware failover. Health-aware failover applies only to operations against the global endpoint — the registry API calls (auth, get manifest, get tag, get referrers, get blob location). It evaluates health when those API calls come in; it does not trigger mid-operation. Two important consequences: Regional endpoints are not in scope. When you talk to a regional endpoint like myregistry.westus.geo.azurecr.io , you're talking to that one replica. There is no automatic reroute. If you've pinned a workload to a regional endpoint and that region degrades, you implement client-side failover by switching the workload to a different regional endpoint. Dedicated data endpoints are not in scope. Once a registry endpoint has redirected you to a dedicated data endpoint, you stay on that region's data endpoint for the duration of the layer download. There is no automatic reroute of an in-flight blob download. The region targeted by the redirect is decided up front by whichever registry endpoint served the blob-location call: the global endpoint chooses based on its per-registry health evaluation, and a regional endpoint always targets its own region. The signals you can use to confirm a failover is in progress: # Check replication status az acr replication list --registry myregistry --output table You can also check Resource Health for the registry in the Azure portal — navigate to your registry and select Resource health under the Help section to see platform-side degradation signals. You'll typically see: Increased pull latency as traffic shifts to a more distant replica Resource Health flagging known issues in the affected region Replication status indicating which replicas are online After the region recovers, the per-registry health evaluation marks it healthy again and the global endpoint resumes routing — automatic, no cooldown, no customer action. Note that health is evaluated per registry, not per region: if a degradation affects only a subset of registries in a region, only those registries are rerouted, and other registries in the same region continue to be served locally with no unnecessary latency penalty. Not triggered by throttling. Health-aware failover is DNS-based and responds to regional ACR service health and Azure infrastructure health. It does not reroute traffic based on HTTP 429 (throttling) responses. If a geo-replica is throttling your requests but the region's infrastructure is healthy, the global endpoint continues routing you to that geo-replica. To manage throttling, use regional endpoints to spread workloads across multiple geo-replicas for better capacity distribution. Note on long-running pushes during a failover. A multi-layer push that spans a failover boundary can land layers and the manifest on different replicas — exactly the failure mode that DNS bouncing produces during a single push. ACR is actively tightening health-aware failover behavior to minimize cross-replica scatter during these scenarios, and the recommendation today remains: pin pushes to a single replica via a regional endpoint when push/pull consistency matters. Common Questions Q1. Performance impact during initial replica creation on a live registry Because ACR is multi-region, multi-write, the existing replica continues serving pull and push traffic throughout the period when a new replica is being seeded. Replication is asynchronous and content propagates in the background; the time to populate a new geo-replica scales with the size of the registry — the cumulative number and total size of images already in the registry — not with any single image. The docs do not publish a quantified degradation percentage or a throttling window for this period, and they do not promise zero performance impact — the safe operating assumption for a live production registry is that existing replicas continue serving traffic normally, with the new replica catching up in the background. Q2. Restricted/updating state during initial sync There is no "restricted" state for the registry during normal replica creation. Writes, control-plane operations, and pushes/pulls against existing replicas continue normally. The only time configuration changes are unavailable is during a home region outage — see the relevant FAQ item later on for the full data-plane-versus-control-plane breakdown. Q3. Cooldown periods and non-straightforward failback scenarios There is no cooldown before failback, manual or automatic. Re-enabling a replica's participation in global endpoint routing takes effect immediately on ACR's side. Health-aware failover returns traffic to a region as soon as its per-registry health evaluation passes again. The failback case that is not seamless: if a recently pushed image has not yet replicated to the failover region, a pull from that region may not find the image until replication catches up. This is a function of eventual consistency, not failback timing — and it's part of a broader class of issues we cover in Q4. Q4. Common pull and push failure modes during the eventual-consistency window DNS bouncing during a single push is one well-known problem, but it isn't the only one. The eventual-consistency window between geo-replicas surfaces in several recurring failure modes worth knowing about: Push-then-immediate-pull-cross-region. Pushing myapp:v1 to one region and immediately pulling it from a different region can fail with manifest unknown until replication catches up. This shows up most painfully in CI/CD pipelines where one CI runner pushes an image and thousands of pods across other regions all try to pull from their local geo-replicas at the same time. Today, customers work around this with indeterminate sleeps before scheduling expensive compute, or with retry logic, or by waiting on a replication-complete signal — none of which is a clean planning story. Tag overwrite races. Pushing myapp:v1 , then re-pushing myapp:v1 shortly after with a fix (same tag, different digest), can leave different replicas resolving the same tag to different digests during the eventual-consistency window. Delete propagation. Deleting a tag or repository in one region takes some time to propagate to other replicas. Pulls from regions where the delete hasn't yet propagated can return the supposedly-deleted content. Mid-push failover scatter. A multi-layer push that spans a health-aware failover boundary or a DNS bouncing event can land layers on one replica and the manifest on another, surfacing as manifest validation errors or blob unknown on subsequent pulls. What ACR is doing about this. We're working on bounded staleness consistency for pushed images across all geo-replicas worldwide, which addresses these four failure modes directly. This will be covered in an upcoming blog post. If you're hitting eventual-consistency brittleness today and want to talk through your scenario, reach out to us on the Azure Container Registry GitHub repository — we want the customer signal to land in the design. Mitigations available today: Pin pushes to a single replica via a regional endpoint. Every sub-request in the push — login, blob uploads, manifest upload — goes to the same replica, eliminating the DNS bouncing and mid-push scatter classes entirely. Use a short-lived client-side DNS cache like dnsmasq scoped to the duration of a single push, only when you're not using regional endpoints. Do not run a long-lived DNS cache for the global endpoint — it interferes with --global-endpoint-routing false and with health-aware failover routing. Build retry logic into pulls that immediately follow a cross-region push. Either retry with backoff or check replication status with ACR webhooks before pulling. ACR can detect and notify you when an image or tag is available for pull in a geo-replica (say geo-replica B), after it has been pushed to another geo-replica (geo-replica A) and background replication has succeeded to geo-replica B. Design publish steps to be idempotent so retries triggered by mid-push failover are safe. Q5. Auth behavior across endpoint switches For safety, treat each global endpoint and each regional endpoint as its own authenticated surface. All registry APIs except the actual blob downloads (auth, manifests, tag resolution, referrers) flow through whichever endpoint you've chosen. If you switch from the global endpoint to a regional endpoint, or from one regional endpoint to another, re-authenticate. That means az acr login , fresh SDK auth, or — for AKS — letting the Kubernetes ACR credential provider handle re-auth, which it does automatically when the endpoint changes. Q6. Throttling under failover and pinning Throttling limits on registry API operations are per-replica, not per-registry. This has two operational implications: During health-aware failover, traffic that was spread across replicas can shift heavily onto whichever replicas remain in the global endpoint's routing pool. Capacity plan to spread traffic across two or three healthy replicas during a failover scenario rather than concentrating onto one — the global endpoint's routing already does this for you when multiple healthy replicas exist, but registries with only two regions configured can hit per-replica limits more easily during a failover. To mitigate, use regional endpoints to spread workloads across multiple geo-replicas and plan per-replica capacity. When pinning via regional endpoints (Step 2a), you concentrate traffic on whichever replica you've pinned to. If you've pinned all your AKS clusters to a single regional endpoint, you may hit that replica's per-region throttling limits at peak. Mitigations: pin different workloads to different regional endpoints across multiple regions for better topology mapping and capacity distribution, or use the global endpoint (Step 2b) for workloads where you don't need explicit pinning so ACR's routing can spread load. We're also working on improving the throttling metrics surfaced during health-aware failover events. Note: Health-aware failover does not reroute traffic based on HTTP 429 (throttling). If you're experiencing throttling but the region's infrastructure is healthy, the global endpoint continues routing you there. Use regional endpoints to explicitly spread load across replicas for capacity planning. Q7. Home region outage scope Geo-replication provides high availability for the data plane. During a home region outage, the control plane is unavailable, which means you can't create or delete replicas, modify network rules, or change replication settings until the home region recovers. ACR Tasks are also bound to the home region and don't run while it's unavailable. The data plane keeps working: Global endpoint continues routing pulls and pushes to healthy replicas. Regional endpoints continue working — you talk directly to specific replicas, and your client-side logic decides which region to use. Authentication, manifests, blob downloads, webhooks continue functioning through any healthy replica. The home region of a registry is fixed at creation and cannot be changed afterward. Microsoft's registry relocation guidance describes a redeployment procedure — creating a new registry in a different region — not an in-place change to an existing registry's home region. Note: If your registry uses a customer-managed key, review the key vault failover and redundancy guidance for maximum resilience. Key vault availability directly affects the registry's ability to encrypt and decrypt data. Q8. Webhooks during failover Webhooks fire from the replica that received the push. Because ACR also replicates content to other geo-replicas, webhooks fire from each geo-replica as the image syncs to it — so a single push results in webhook events from the receiving replica plus an event from each replica as replication completes. During a failover where pushes are routed to a different region, webhooks from those pushes fire from the new region; once the original region recovers and replication catches up, webhook events fire from there too. Webhook consumers should be designed to handle multiple events per pushed image and deduplicate as needed. Q9. Private endpoints with regional endpoints and dedicated data endpoints When a private endpoint is created against a registry, the private endpoint covers all of the registry's endpoint surfaces — the global endpoint, every regional endpoint (if regional endpoints are enabled), and every regional dedicated data endpoint. A single private endpoint in one VNet can reach the global endpoint (which routes you to a suitable replica), any regional endpoint in the same or a different region, and any region's dedicated data endpoint for blob downloads. The trade-off is private IP allocation: each endpoint surface consumes IPs in the VNet. With many replicas plus regional endpoints plus dedicated data endpoints all enabled, private endpoint creation can fail if the VNet runs out of available private IPs. IP address consumption per feature: Configuration IPs consumed per VNet Initial private endpoint (global endpoint + home region dedicated data endpoint) 2 Each geo-replication region added +1 (regional dedicated data endpoint) Regional endpoints enabled +1 per geo-replica Example: A registry with 3 geo-replicas and regional endpoints enabled consumes 7 private IPs per VNet: 1 (global) + 3 (data) + 3 (regional). Without regional endpoints, the same registry requires 4 private IPs: 1 (global) + 3 (data). Subnet sizing: Use at minimum a /27 (32 addresses) subnet for PE subnets on geo-replicated registries, and /24 where possible. To check how many private IPs are already consumed on a subnet: az network vnet subnet show \ --name <subnet-name> \ --vnet-name <vnet-name> \ --resource-group <resource-group> \ --query "{addressPrefix:addressPrefix, usedIPs:length(ipConfigurations || \`[]\`)}" \ --output table See the ACR private endpoints documentation for the full IP-allocation math and sizing guidance. Q10. Geo-replica creation stuck for private endpoint-enabled registries When creating a geo-replica for a registry that has private endpoints configured, the replica provisioning can get stuck in a Creating state if the identity performing the operation doesn't have sufficient permissions to create private endpoint networking resources. Solution: Manually delete the geo-replica that got stuck in the provisioning state. Ensure the identity has the permission Microsoft.Network/privateEndpoints/privateLinkServiceProxies/write before creating the geo-replica again. Also verify that every PE subnet connected to the registry has free IP capacity — if any PE subnet across any connected VNet does not have enough free IPs, the replication provisioning fails and rolls back. The replica appears briefly in a Creating state and then is removed. The resulting error does not identify which subnet or VNet is exhausted. Q11. Metrics, logs, and alerts for the three phases We map each phase to the signals available in the Monitoring Guidance section below. The headline: Resource Health (in the Azure portal) and az acr replication list give you the platform-side signals; Azure Monitor platform metrics are collected automatically, and resource logs require Diagnostic Settings to be enabled on the customer side. Behavior summary Scenario Automatic? Customer Action Required Notes Registry in a region degrades Yes None Health-aware failover; per-registry; minutes-scale; global endpoint operations only Region recovers after a degradation event Yes None No cooldown Pin AKS clusters to co-located replicas No Use regional endpoint URLs in deployment manifests (Step 2a) Coexists with global endpoint No pinning needed for most workloads Yes None — keep using myregistry.azurecr.io (Step 2b) Global endpoint plus health-aware failover Push/pull from the same replica (consistency) No Use a regional endpoint for both push and pull Eliminates DNS bouncing and mid-push scatter Capacity planning per region No Spread workloads across multiple regional endpoints Per-replica throttling; avoid concentrating on one replica DR rehearsal: take a replica out of global routing No az acr replication update --global-endpoint-routing false Data continues syncing both directions; costs continue accruing Re-enable replica participation in global routing No az acr replication update --global-endpoint-routing true No cooldown; replica is immediately ready Switch a workload between endpoints No Re-auth ( az acr login , SDK auth, or Kubernetes ACR credential provider) Each endpoint is its own authenticated surface Initial replica seeding on a live registry N/A None Existing replica continues serving traffic; seeding time scales with registry size Long-running push during a failover No Retry; design publishes to be idempotent Pin via regional endpoint to avoid mid-push scatter; ACR is tightening this behavior Pull of a recently pushed image from a different region No Wait for replication, retry with backoff, or check replication status Eventual consistency; bounded staleness consistency in development Home region outage Data plane: yes; control plane: no Use global or regional endpoints for data plane operations Control plane (replica config, network rules) requires home region DNS and Client-Side Considerations DNS bouncing during a single push is the most common geo-replication push problem in customer threads, and it warrants a section of its own. The failure mode. A docker push is a sequence of HTTP requests: blob uploads for each layer, then a manifest upload that references those layers by digest. If the Linux DNS resolver on the client doesn't cache myregistry.azurecr.io consistently for the duration of the push, individual sub-requests can resolve to different replicas. Because replication is eventually consistent, the manifest can land on a replica that doesn't yet have the layers it references, and the manifest validation fails. The two mitigations: Regional endpoints pin the push to a single replica end-to-end. Every sub-request — login, blob uploads, manifest upload — goes to the same replica. This is the cleanest fix and the one we recommend for any pipeline where push/pull consistency matters. A short-lived client-side DNS cache like dnsmasq scoped to the duration of a single push. For Linux VMs in Azure, follow the DNS name resolution options guidance. The pin should last the push and no longer. For other clients performing pushes, you can customize your stack's DNS resolver to have a similar short-lived DNS cache to pin the global endpoint's resolved DNS for only the duration of an image push operation. A note on long-lived DNS caching for the global endpoint. Don't run a long-lived DNS cache for myregistry.azurecr.io . ACR purges its own DNS records on the server side when a replica is taken out of global routing (Step 3) and during health-aware failover; a long-lived client-side cache will keep clients pointed at the old region after our purge, which makes both the manual disable mechanism and health-aware failover look broken from the client's perspective. Retry behavior: In-flight pushes during a failover may fail. Design publish steps to be idempotent so retries are safe. Pipelines that push in one region and immediately pull from a different region should retry with backoff or check replication status — eventual consistency means the pull may race ahead of replication. ACR is working on bounded staleness consistency that addresses this directly by enabling proxying (on ACR infrastructure) an image pull request from one geo-replica (if it does not have the image) to another geo-replica that has the image; see the relevant FAQ item. Note: Specific retry counts, back-off intervals, and push timeout values are application-layer decisions. The platform behavior is documented; the retry policy belongs to your client. Monitoring Guidance We map the three phases to the signals available from each source. Where a signal requires customer-side configuration, we flag it. Phase A: Initial replication (after creating a new replica) az acr replication list and az acr replication show — confirm the new replica reaches provisioningState: Succeeded and status: online , and view per-replica status. Azure Monitor platform metrics — push count, pull count, and other registry metrics are collected automatically and visible in the Azure portal under Metrics. No customer configuration is needed to view platform metrics. To export metrics or enable resource logs (detailed operation logs), configure Diagnostic Settings on the registry. Phase B: Failover (planned via replica disable, or automatic via health-aware failover) Per-replica regionEndpointEnabled state via az acr replication list — confirms whether a manual disable took effect, i.e. which replicas are currently eligible for global endpoint routing. Note: this flag reflects the manual configuration for configuring a geo-replica's global endpoint routing eligibility; it does not indicate whether health-aware failover has actively rerouted traffic away from a replica. Resource Health for the registry (in the Azure portal under Help > Resource health) — surfaces platform-side degradation signals during incidents. ACR does not yet expose a definitive "this region is currently serving your traffic" signal; Resource Health and client-side latency changes are the best available indicators. Pull latency from clients — increased latency from a more distant replica is the client-observable signal that traffic has rerouted. Azure Monitor platform metrics — visible per-region in the Azure portal Metrics blade. To export metrics or query them programmatically, enable Diagnostic Settings. Phase C: Failback (replica returns to global routing) az acr replication list — confirms regionEndpointEnabled: True (manual) or online status across all replicas (automatic). Pull latency normalizing as clients reach the recovered replica again. Resource Health clearing for the registry (visible in the Azure portal). Note: The health-aware failover blog calls out ongoing work to surface richer signals — including notifications for when routing changes and which region is currently serving your traffic. The signals listed above are what's available today. Pricing Considerations Storage billing vs. storage quota: Storage is billed per geo-replica — a 1 GiB image replicated to 5 geo-replicas is charged as 5 GiB of storage (1 GiB × 5 geo-replicas). However, storage quota (the tier's maximum storage limit) counts the image only once — the same 1 GiB image counts as 1 GiB toward your tier's maximum, not 5 GiB. Data transfer: Geo-replication can reduce costs by enabling in-region image pushes and pulls, which avoids cross-region data transfer charges during these push or pull operations. However, cross-region data transfer charges still apply when ACR replicates pushed content to other geo-replicas as part of eventual consistency. Disabled replicas still cost: When you take a replica out of global routing with --global-endpoint-routing false , storage and per-replica costs continue accruing because data continues syncing bidirectionally. For more information, see ACR pricing. Cleanup Run these commands to undo the walkthrough setup. Order matters: disable regional endpoints before deleting replicas, since regional endpoint URLs depend on which replicas exist. # Disable regional endpoints if you enabled them in Step 2a az acr update -n myregistry -g myrg --regional-endpoints disabled # Re-enable any replicas you disabled in Step 3 (no-op if already enabled) az acr replication update --registry myregistry --name westus \ --global-endpoint-routing true # Delete the West US replica created in Step 1 az acr replication delete --registry myregistry --name westus # Confirm only the home region replica remains az acr replication list --registry myregistry --output table Note: Replica deletion is a control-plane operation that requires the home region to be available. During a home region outage, replica configuration cannot be modified. Summary Table Question Answer When should I use regional endpoints vs the global endpoint? Use regional endpoints (Step 2a) for workloads that need affinity, predictable routing, push/pull consistency, troubleshooting, or client-side failover. Use the global endpoint (Step 2b) for everything else and let health-aware failover handle routing. What should I enable for secure, resilient layer downloads? Enable dedicated data endpoints. They scope firewall rules tightly to your registry and replace wildcard storage DNS with predictable per-region FQDNs. How do I avoid DNS-bouncing manifest validation failures on push? Pin pushes to a single replica via a regional endpoint. A short-lived client-side dnsmasq for the push duration is also fine if you're not using regional endpoints. Should I run a long-lived DNS cache for the global endpoint? No. ACR purges DNS server-side on disable and during failover; client-side caching works against that. Do I need to re-auth when switching endpoints? Yes. Each global or regional endpoint is its own authenticated surface. az acr login , SDK auth, or the Kubernetes ACR credential provider handles the re-auth. What happens during a home region outage? Data plane keeps working through any replica via the global endpoint or regional endpoints. Control plane operations (replica configuration, network rules) are unavailable until the home region recovers. The home region is fixed at registry creation. What's ACR doing about eventual-consistency pain? Bounded staleness consistency for cross-replica pushed images is in development and will be covered in an upcoming blog post. Reach out via GitHub if you want to share your scenario. For the full automation matrix — what's automatic, what requires customer action, and what to expect for each scenario — see the behavior summary above. If you have further questions about ACR geo-replication routing, pinning, capacity planning, eventual consistency, or failover behavior, reach out to us on the Azure Container Registry GitHub repository or file feedback through the Azure portal.Managed Connectors for SRE Agent (preview)- Govern what your agent can do
Giving an agent access to a tool is the easy part. The harder question is what it's allowed to do with that access. "Can the agent copy a file in OneDrive?" mostly answers itself. "Can it copy any file, to any destination, over one that's already there?" is the one that decides whether the integration has a governance layer. Managed Connectors is built around that second question. It expands the catalog of tools the agent can reach - OneDrive, SharePoint, Google Drive, GitLab, Power BI, Microsoft Security Copilot, with more being added regularly - and pairs it with a governance model that keeps the policy for those tools outside the agent's control. This is part of the Azure SRE Agent announcements at Build 2026 What's new Managed Connectors is the next generation of our connector experience. It significantly expands the catalog of third-party and first-party SaaS integrations available to SRE Agent and surfaces each one to the agent as a curated set of operations through the Model Context Protocol (MCP) - the same standard the agent already uses for every other tool source. Governance: the agent gets capability, you keep control The governance model is the headline of this release, so it's worth being concrete about it. When you add a connector, you walk through a short wizard - Set up connector, Configure tools, Review & Save - and the "Configure tools" step is where the policy is set. Three things make it different from "just wire the API up to the LLM": You choose what's exposed - it isn't automatic. A connector might offer 40+ operations; in the wizard you pick the ones the agent can use. The rest aren't shown to the model, so it can't call them. Parameter policy lives outside the agent. For each selected operation you can mark parameters as user-defined (pinned to a value you specify) or agent-defined (the agent fills it in). On the Microsoft Planner “Create a task” tool, for example, you can choose the group ID from a list of your joined groups – this means that the agent provides the task details but can’t assign it to any arbitrary group, because that isn’t a parameter it sees when invoking the tool. Per-tool approval is built in. Each operation has an Allow/Ask toggle integrated directly into the creation and edit wizards. "Ask" routes the call through the agent runtime human-in-the-loop approval flow before it executes. On that same Microsoft Planner connector, you might leave read-only tools like “List tasks” or "Get plan details” on Allow, but flip “Delete a task” to Ask so a human must confirm before anything is removed. This is enforced on the agent's runtime; it is not a prompt instruction the model can be talked out of following. Credential Isolation No long-lived secrets in the agent. No API keys, no client secrets, no certificates, no OAuth tokens. All service credentials are encrypted at rest and stored outside of the agent’s trust boundary Automatic token refreshed. Once you consent, the internal connector resource keeps your tokens valid. You won't be asked to re-authenticate unless your service itself requires it. You consent once, in your own browser, with your own service. SRE Agent never proxies your password or the sign-in flow. Per-connection authorization. Each connection is bound to the specific SRE Agent instance you set up on and cannot be used by external threat actors. How it fits together All of this is stored and evaluated outside the agent loop. Each configured connector becomes an MCP server that the SRE Agent runtime registers as a tool source, the same standard wire format the agent uses for everything else, so adoption on the model side is trivial. Each layer does one job, and the trust boundary between "what the model decided" and "what was actually sent" is explicit and inspectable: the agent never sees the operations you didn't select, never sees the parameter slots you pinned, and cannot bypass approval on operations you marked Ask. How to try it Open the SRE Agent portal and go to Builder > Connectors. Pick a connector from the catalog with the “Preview” label and go through the creation wizard steps. At the “Set up connector” step, choose how the connector authenticates. Start with “OAuth” if you just want to sign-in and see it working against your own account. At “Configure tools”, select the operations you want to expose, pin any parameters that shouldn't be agent-controlled, and mark sensitive operations as “Ask.” Review & Save. The connector is registered with the runtime and immediately available to your agent. You can enable/disable specific tools or connectors in the “Capabilities” section. Edit connector – after creating the new connector, at any point you can go back and authenticate it with a different account, add or remove operations, update tool parameters and configure approval policies Resources Create new SRE Agent — https://aka.ms/sreagent SRE Agent Documentation — https://aka.ms/sreagent/newdocs SRE Agent recipes — https://aka.ms/sreagent/recipes Build 2026 SRE Agent announcements - https://aka.ms/Build26/blog/SREAgent
