IPv6 Dual-Stack Endpoints for Azure Container Registry (Public Preview)
By Johnson Shi, Aviral Takkar, Bin Du Introduction Two of the most common networking questions we hear from teams running Azure Container Registry (ACR) are: "Can my registry serve clients on IPv6 networks?" — Teams operating IPv6-only or dual-stack networks need their container registry reachable over IPv6. "How do we start moving registry traffic toward IPv6 without breaking anything?" — Organizations guarding against IPv4 address exhaustion, or operating under IPv6 transition mandates, want a migration path that doesn't disrupt existing IPv4 clients. Today, we're announcing the public preview of IPv6 dual-stack endpoints for Azure Container Registry for public endpoints and firewall rules, with IPv6 over private endpoints planned for GA. Set your registry's endpoint protocol to IPv4AndIPv6 , and its endpoints become reachable over both IPv4 and IPv6 — so IPv4-only, dual-stack, and IPv6-capable clients all connect to the same registry, each over whichever protocol their network stack selects. Key Takeaways ACR registries now support an endpointProtocol setting with two values: IPv4 (default) and IPv4AndIPv6 (dual stack, preview). Dual stack is additive — your registry continues serving IPv4 clients exactly as before. There is no IPv6-only mode. Dual stack requires dedicated data endpoints to be enabled ( --data-endpoint-enabled true ), and dedicated data endpoints require the Premium SKU. The service enforces this requirement. You can enable it today with Azure CLI 2.87.0 via az acr update --endpoint-protocol IPv4AndIPv6 . FQDN-based client firewall rules keep working unchanged; IP-based allowlists need to account for IPv6 traffic. Limitation: This public preview covers IPv6 for the registry's public endpoints and firewall rules only. IPv6 over private endpoints is planned for a future release. Limitation: ACR Tasks isn't supported on a registry that has IPv6 dual-stack enabled. Tasks does not work when the endpoint protocol isIPv6 dual-stack, including quick builds (with az acr build) and quick task runs (with az acr run). Support is planned for a future release. How to enable it On an existing registry (Azure CLI 2.87.0 or later) Dual stack requires dedicated data endpoints, so enable both in a single update: az acr update --name <your-registry> --data-endpoint-enabled true --endpoint-protocol IPv4AndIPv6 If dedicated data endpoints are already enabled, set the endpoint protocol on its own: az acr update --name <your-registry> --endpoint-protocol IPv4AndIPv6 Verify the configuration: az acr show --name <your-registry> --query "{endpointProtocol:endpointProtocol, dataEndpointEnabled:dataEndpointEnabled}" { "dataEndpointEnabled": true, "endpointProtocol": "IPv4AndIPv6" } Note: If your clients sit behind a firewall and you're enabling dedicated data endpoints for the first time, add firewall rules for <your-registry>.<region>.data.azurecr.io before enabling — switching from *.blob.core.windows.net to dedicated data endpoints changes where layer blobs are downloaded from. See Dedicated data endpoints for details. Reverting to IPv4 Dual stack is reversible at any time: az acr update --name <your-registry> --endpoint-protocol IPv4 Reverting the endpoint protocol leaves dedicated data endpoints enabled; disable them separately if desired. Scope of this preview This public preview enables IPv6 for the registry's public endpoints — the login server, dedicated data endpoints, and regional endpoints (if enabled). IPv6 over private endpoints isn't part of this preview. Support is planned for a future release. Until then, registries reached through a private endpoint continue to use IPv4. Additionally, IPv6 dual-stack support for ACR Tasks, including support for `az acr build` and `az acr run`, are not supported in the public preview. Support is planned for a future release. Requirements and how features compose Requirement Why Premium SKU Dedicated data endpoints are a Premium feature. Dedicated data endpoints enabled IPv4AndIPv6 requires dataEndpointEnabled: true ; the service rejects the setting otherwise. Azure CLI 2.87.0+ Adds --endpoint-protocol to az acr update . For geo-replicated registries, the endpoint protocol is a registry-level setting, and dedicated data endpoints exist in every replica region. Firewall guidance: rules based on registry FQDNs — the login server, dedicated data endpoints, and regional endpoints (if enabled) — continue to work unchanged for dual-stack registries; only IP-address-based allowlists need updating for IPv6. To learn more, see IPv6 dual-stack endpoints in Azure Container Registry (preview) and the ACR endpoint reference. If you have further questions about IPv6 dual-stack endpoints or dedicated data endpoints, reach out to us on the Azure Container Registry GitHub repository or file feedback through the Azure portal.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/SREAgentPrivate Plugins with Azure SRE Agent
SRE's and platform teams are building operational skills specific to their infrastructure: investigation runbooks, compliance checks, cost analysis playbooks, deployment verification procedures. The next step is making that work reusable across every agent in the organization without exposing it publicly. Today, SRE Agent supports plugin marketplaces hosted in private GitHub repositories, including GitHub Enterprise. This is part of the Azure SRE Agent announcements at Build 2026. You can now point SRE Agent at a private repo when adding a marketplace or installing a plugin. Authentication is handled per-marketplace, and supports OAuth, GitHub PATs, and GitHub Apps for GHE tenants. From one agent to an organization’s plugin catalog Most teams start with a single SRE Agent connected to their services. The agent learns their infrastructure, runs their runbooks, and handles their incidents. It works well. Then adoption grows. A second team stands up their own agent. Then a third. Platform engineering wants every agent to run the same compliance checks. Security needs approval hooks enforced consistently. FinOps has cost governance skills that should be standard across the organization. Suddenly the question isn’t “how do I set up my agent,” it’s “how do we share operational knowledge across all of them.” Without a distribution model, teams end up copying skill files between agents manually. A platform team writes a runbook, shares it over email or a wiki link, and each service team pastes it into their agent individually. When the runbook improves, some agents get updated, some don’t. There’s no version tracking, no central catalog, and no way to know which agent is running which version of which skill. Private marketplace support solves this. How Private Plugin marketplace meet enterprise needs A platform team publishes once, every agent installs. Codify best practices as plugins in a private GitHub repo. Service teams add that repo as a marketplace in their agents and install what they need. Compliance checks, cost governance thresholds, incident playbooks, deployment verification procedures all distributed through versioned plugins. Each team retains ownership. Security controls which plugins enforce approval hooks. FinOps locks cost thresholds into parameter values. Platform engineering governs infrastructure investigation patterns. The marketplace is the distribution layer for organizational standards. Versions are pinned, updates are explicit. Each installation locks to the commit at install time. A merged PR upstream does not change any agent’s behavior. Teams promote new versions on their own schedule: validate in dev, promote to staging, then production. Different agents can run different versions simultaneously. Reuse across environments and tools. The same plugin works across dev, staging, and production agents, and can be reused by local coding agents and other services that support plugins. One source of truth, not separate copies per environment. Accessing Private Plugin marketplaces Private repo support adds authentication to the SRE Agent's plugin workflow so your agent can clone and install from repos that require credentials. Authentication is configured once per marketplace. Every plugin within it inherits the credentials. Auth method When to use Setup OAuth github.com repos your agent can already access Uses your existing GitHub connection. One click. Personal access token Private repos in other orgs on github.com Per-marketplace PAT. Scoped to just that marketplace. GitHub App GitHub Enterprise (*.ghe.com) BYO App with private key in Azure Key Vault. Short-lived tokens minted at runtime. Getting started In SRE Agent, navigate to Builder > Plugins, then click Add Marketplace and enter the URL of the private marketplace you want to connect to. Then click Connect to GitHub to complete the OAuth sign-in. Click Add and you will see the plugins available from your connected marketplace. Click on the plugin to install and in the detail view you can browse the skills packaged with the plugin. click Install to install this plugin. You can now see the skills imported from plugins from Capabilities > Skills > Custom Skills The bottom line Private repo support turns the Plugin Marketplace from a public skill catalog into your organization’s internal distribution platform for operational automation. Your team writes the plugins. Your agents install them. Your GitHub permissions control who has access. Try it yourself: create a private repo with a marketplace.json and a few skills, add it as a marketplace in your agent, and install a plugin. Resources SRE Agent documentation — https://aka.ms/sreagent/newdocs SRE Agent overview — https://aka.ms/sreagent/newdocsoverview Plugin Marketplace capability page — https://aka.ms/sreagent/newdocs/capabilities/plugin-marketplace Build 2026 SRE Agent announcements - https://aka.ms/Build26/blog/SREAgentShaping 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.Regional Endpoints for Azure Container Registry Geo-Replication — Now in Public Preview
By Johnson Shi, Zoey (Zhuyu) Li, Huangli Wu What's new Regional endpoints for geo-replicated Azure Container Registries are now in public preview. See the feature's official MS Learn documentation. If you've been following since the private preview announcement, here's what changed: No feature flag registration. No subscription enrollment so all Azure subscriptions and customers can now use this feature. No CLI extension. Regional endpoints commands are built into Azure CLI 2.86.0+ natively. If you installed the private preview acrregionalendpoint extension, uninstall it to avoid conflicts. Native CLI and portal support. With Azure CLI 2.86.0+, enable regional endpoints for all geo-replicas of a registry with az acr create --regional-endpoints enabled or az acr update --regional-endpoints enabled . The Azure portal also supports configuring regional endpoints natively. CLI flag rename for configuring a geo-replica's global endpoint routing (an existing separate feature). The existing flag --region-endpoint-enabled (on az acr replication create/update ) has been renamed to --global-endpoint-routing . Key clarifications: "--global-endpoint-routing" (formerly "--region-endpoint-enabled" on "az acr replication create / az acr replication update") — controls whether a specific geo-replica participates in global endpoint routing. This is an existing feature that is different from the new registry-level "--regional-endpoints" feature being discussed in this post. "--regional-endpoints" (on az "acr create / az acr update") — enables or disables the regional endpoints feature at the registry level for all geo-replicas. This is the feature discussed in this post. See the endpoint reference for the full breakdown of the various registry endpoints (global endpoints, regional endpoints, and data endpoints). Regional endpoints are available on Premium SKU registries in all Azure public cloud regions. What are regional endpoints? Regional endpoints give you dedicated, per-region login server URLs for each geo-replica with the following URL pattern: myregistry.eastus.geo.azurecr.io myregistry.westeurope.geo.azurecr.io Regional endpoints coexist with the registry's global endpoint ( myregistry.azurecr.io ) — enabling regional endpoints doesn't disable a registry's global endpoint that is backed by Azure-managed routing. You can choose per workload: You can use the global endpoint with automatic Azure-managed routing with health-aware failover, where Azure will route your requests to the geo-replica with the best network performance profile to the client. You can use a regional endpoint when you need explicit control or routing to a specific geo-replica. Other resources: For the full background on why regional endpoints exist and the problems they solve, see the private preview blog post. For the complete operational deep dive — health-aware failover, throttling considerations, storage quota and pricing, eventual consistency, home region outage behavior, DNS propagation, private endpoint interaction, capacity planning, and monitoring guidance — see How ACR geo-replication handles failover, failback, and traffic redirection. For the behind-the-scenes engineering implementation — architectural overview and the engineering system design of the feature — see Determinism over magic: the engineering design behind Azure Container Registry Regional Endpoints. Getting started Enable regional endpoints on an existing registry: az acr update -n myregistry -g myrg --regional-endpoints enabled View all registry endpoint URLs, including the registry global endpoint, geo-replica regional endpoints, and data endpoints: az acr show-endpoints --name myregistry --resource-group myrg Using regional endpoints Authenticate to a specific regional endpoint: az acr login --name myregistry --endpoint eastus Push to a specific geo-replica. Images and tags pushed to a geo-replica via regional endpoints still propagate to all other geo-replicas under eventual consistency. docker tag myapp:v1 myregistry.eastus.geo.azurecr.io/myapp:v1 docker push myregistry.eastus.geo.azurecr.io/myapp:v1 Pull an image: docker pull myregistry.eastus.geo.azurecr.io/myapp:v1 You can specify regional endpoints directly in Kubernetes deployment manifests if you need to pin workloads to specific regions. This ensures clusters in specific regions always pull from their colocated replica, providing predictable routing and reduced latency. By using different regional endpoints in each cluster's manifests, you can choose to guarantee that each cluster pulls from its local replica instead of relying on Azure-managed routing. East US cluster deployment: 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 cluster deployment: apiVersion: apps/v1 kind: Deployment metadata: name: myapp-westeurope spec: template: spec: containers: - name: myapp image: myregistry.westeurope.geo.azurecr.io/myapp:v1 When to use regional endpoints Scenario What to do Most workloads Keep using the global endpoint ( myregistry.azurecr.io ). Health-aware failover handles routing automatically. Pin AKS clusters to co-located replicas Use regional endpoint URLs in deployment manifests. CI/CD push-then-pull consistency Pin pushes to a regional endpoint to avoid eventual-consistency races. Client-side failover Switch between regional endpoints based on your own health checks. Capacity planning Spread workloads across multiple regional endpoints to avoid per-replica throttling. Troubleshooting Target a specific geo-replica to reproduce or isolate an issue. What changed from private preview Private preview Public preview Feature flag registration required ( az feature register ) No registration needed Subscription private preview enrollment and propagation wait Immediately available to all Azure subscriptions for all Premium SKU registries in all Azure public cloud regions. Separate CLI extension ( acrregionalendpoint ) Built into Azure CLI 2.86.0+ natively No registry-level CLI flag az acr update --regional-endpoints enabled enables regional endpoints for all geo-replicas --region-endpoint-enabled flag for controlling a geo-replica's global endpoint routing via az acr replication update Flag for controlling a geo-replica's global endpoint routing renamed to --global-endpoint-routing No portal support Native Azure portal support for enabling regional endpoints for new registries (during creation) and for existing registries Private preview docs in Azure/acr Full documentation on MS Learn Enabling regional endpoints in the Azure portal You can enable regional endpoints directly from the Azure portal for both new registries (during creation), as well as existing registries: If you were in the private preview 1. Uninstall the CLI extension. The private preview CLI extension conflicts with the built-in commands in Azure CLI 2.86.0+. Remove it: az extension remove --name acrregionalendpoint Verify it's gone: az extension list --query "[?name=='acrregionalendpoint']" -o table 2. Ensure you're running Azure CLI 2.86.0 or later. Regional endpoints commands are available natively starting in Azure CLI 2.86.0. Check your version: az version 3. Update scripts that use --region-endpoint-enabled for controlling global endpoint routing for a geo-replica. The old flag name for controlling a geo-replica's global endpoint routing configuration is deprecated and will be removed in Azure CLI 2.87.0 (June 2026). Update to --global-endpoint-routing : # Old (deprecated) az acr replication update --registry myregistry --name westus \ --region-endpoint-enabled false # New az acr replication update --registry myregistry --name westus \ --global-endpoint-routing false Why the rename? The old flag name --region-endpoint-enabled was confusing — it sounded like it controlled the regional endpoints feature, but it actually controlled whether a geo-replica participates in global endpoint routing. The new name --global-endpoint-routing says exactly what it does. For a full breakdown of all three CLI flags and how they relate, see the endpoint reference. Learn more Full documentation: Geo-replication in Azure Container Registry — Regional endpoints — prerequisites, CLI commands, network considerations, private endpoint integration, and troubleshooting. Operational deep dive: How ACR geo-replication handles failover, failback, and traffic redirection — health-aware failover, throttling, eventual consistency, DNS considerations, monitoring, pricing, and a full walkthrough. Behind-the-scenes engineering implementation: Determinism over magic: the engineering design behind Azure Container Registry Regional Endpoints — architectural details and the engineering system design behind the feature. Endpoint reference: Azure Container Registry endpoint reference — all endpoint types, URL formats, and CLI flags in one place. Private endpoints: Connect privately to a registry using private endpoints — IP allocation math, subnet sizing, and NIC queries for registries with regional endpoints. Firewall rules: Configure firewall access rules — which FQDNs to allow for regional endpoints. Feedback We'd love to hear how you're using regional endpoints and what we can improve. Reach out via: Azure Container Registry GitHub repository — issues, feature requests, and discussion Azure portal feedback — use the feedback button in the Azure portal on your registry's page Regional endpoints are on the path to GA. Your feedback directly shapes the feature's direction.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/SREAgentAzure Functions MCP extension now supports MCP Prompts
We are thrilled to announce that the MCP prompt trigger is now available in public preview in the Azure Functions MCP extension! With this release, the extension now supports all three core MCP server primitives - tools, resources, and prompts, giving you a complete platform for building rich MCP servers on Azure Functions. In case you missed it, the MCP resource trigger is generally available for serving resources and building interactive UIs in MCP Apps. What are MCP Prompts In the Model Context Protocol (MCP), prompts are reusable templates that allow server authors to provide parameterized prompts for a domain, or showcase how to best use the MCP server. Prompts are user-controlled in that they require explicit invocation rather than automatic triggering, and can be context-aware, referencing available resources and tools to create comprehensive workflows. Unlike tools (which are model-controlled) and resources (which are application-controlled), prompts are exposed from servers to clients so users can explicitly select them. Applications typically expose prompts through slash commands, command palettes, dedicated UI buttons, or context menus. How It Works In Python, defining a prompt is as simple as decorating a function. Here's a prompt that returns a code review checklist: app.mcp_prompt_trigger( arg_name="context", prompt_name="code_review_checklist", description="Returns a structured code review checklist prompt for evaluating code changes." ) def code_review_checklist(context: func.PromptInvocationContext) -> str: logging.info("Code review checklist prompt invoked.") return """You are a senior software engineer performing a code review. Use the following checklist to evaluate the code: 1. **Correctness** — Does the code do what it's supposed to? 2. **Error Handling** — Are edge cases and failures handled? 3. **Security** — Are there any vulnerabilities (injection, auth, secrets)? 4. **Performance** — Are there obvious inefficiencies? 5. **Readability** — Is the code clear and well-named? 6. **Tests** — Are there adequate tests for the changes? Provide your feedback in a structured format with a severity level (critical, warning, suggestion) for each finding.""" Prompts can accept arguments, allowing clients to customize the generated message. Here's a prompt that generates documentation with configurable parameters: app.mcp_prompt_trigger( arg_name="context", prompt_name="generate_documentation", prompt_arguments=[ func.PromptArgument("function_name", "The name of the function to document.", required=False), func.PromptArgument("style", "Documentation style: 'concise', 'detailed', or 'tutorial'.", required=False) ], description="Generates API documentation for a function. Arguments are configured in Program.cs." ) def generate_documentation(context: func.PromptInvocationContext) -> str: function_name = context.arguments.get("function_name", "(unknown)") style = context.arguments.get("style", "concise") logging.info(f"Generate docs prompt invoked for function: {function_name}") return f"""Generate API documentation for the function named **{function_name}**. Documentation style: **{style}** Include the following sections: - **Description** — What the function does. - **Parameters** — List each parameter with its type and purpose. - **Return Value** — What the function returns. - **Example Usage** — A short code example showing how to call it.""" Checkout the Get Started section for the complete sample and samples in different languages. Why Azure Functions Azure Functions is the ideal platform for hosting remote MCP servers because of its built-in MCP authentication, event-driven scaling from 0 to N, and serverless billing. This ensures your agentic tools are secure, cost-effective, and ready to handle any load. With the MCP extension, you focus on implementing the primitives you want to expose, tools, resources, and prompts, instead of worrying about MCP protocol details and server logistics. Get Started You can start building today using our quickstarts and samples: Python TypeScript .NET Java Documentation Azure Functions MCP extension overview Prompt trigger We'd Love to Hear from You! Let us know your thoughts about the new prompt trigger. What kinds of prompts are you building for your MCP servers? What would you like us to prioritize next? Share your feedback in our GitHub repo.Introducing Azure Container Apps Express!
Three years ago, a 15-second cold start was industry-leading. Today, developers and AI agents expect sub-second. The speed bar has moved, and the tooling needs to move with it. After running Azure Container Apps for years, we've learned something important: for most developers, the ACA environment is an unnecessary construct. It adds provisioning time, configuration surface, and cognitive overhead — when all you really want is to run your app with scaling, networking, and operations handled for you. At the same time, a new class of workloads has emerged. Agent-first platforms — systems where AI agents deploy endpoints on demand, spin up tool-use APIs, and tear them down when work is done — demand an even more radical focus on speed and simplicity. Every second of provisioning delay is wasted agent productivity. Today, we're launching Azure Container Apps Express in Public Preview — the fastest, simplest way to go from a container image to an internet-reachable app on Azure, ready for many production-style workloads. What Is ACA Express? ACA Express removes the infrastructure decisions. There's no environment to provision, no networking to configure, no scaling rules to write. You bring a container image, Express handles everything else. Behind the scenes, Express runs your container on pre-provisioned capacity with sensible defaults baked in — so you skip environment setup without giving up ACA's serverless model. There's more coming in this space soon — keep watching. Here's what that means in practice: Instant provisioning — your app is running in seconds, not minutes Sub-second cold starts — fast enough for interactive UIs and on-demand agent endpoints Scale to and from zero — automatic, no configuration required (full scaling controls coming soon) Per-second billing — pay only for what you use Production-ready defaults — ingress, secrets, environment variables, and observability are built in Express is purpose-built for two audiences: developers who want to ship fast (SaaS apps, APIs, web dashboards, prototypes) and agents that deploy on demand (MCP servers, tool-use endpoints, multi-step workflow APIs, human-in-the-loop UIs). If you've ever waited for an ACA environment to provision, only to realize you didn't need half of the configuration options it asked you for — Express is your answer. What You Can Do Today Note: West Central US is currently the only available region. We will expand to new regions through the coming days. Express is in Public Preview starting today. It's a deliberate early ship — there's a meaningful feature gap compared to the existing Azure Container Apps offering, and we're filling it fast. New capabilities are landing on a rapid cadence throughout the preview, and by Microsoft Build in June, Express should be close to feature-complete. For the current list of supported features, known gaps, and what's on the way, see the Express documentation. We'd rather put valuable technology in your hands early and iterate with you than wait behind closed doors for perfection. Who Is Express For? Scenario Why Express SaaS apps and APIs Deploy and scale without infrastructure planning AI app frontends Chat UIs and copilot frontends that scale with usage spikes MCP servers Expose API endpoints for AI agents in seconds Agent workflows Spin up endpoints on demand, tear down when done Prototypes and startups Go from idea to production in minutes Web dashboards Internal tools with instant availability Get Started Express is available now in Public Preview. Try it: Azure Container Apps Express overview — concepts, capabilities, and the current feature support matrix Deploy your first app with the Azure CLI — step-by-step quickstart New Azure Container Apps Portal — create and manage Express apps alongside your existing Container Apps resources Have questions? Check the Azure Container Apps Express FAQ for answers to common questions about pricing, limits, regions, and the road to GA. We're building Express in the open and we want to hear from you. Tell us what features matter most, what works, and what doesn't — reach out on the Azure Container Apps GitHub or in the comments below.The Agent that investigates itself
Azure SRE Agent handles tens of thousands of incident investigations each week for internal Microsoft services and external teams running it for their own systems. Last month, one of those incidents was about the agent itself. Our KV cache hit rate alert started firing. Cached token percentage was dropping across the fleet. We didn't open dashboards. We simply asked the agent. It spawned parallel subagents, searched logs, read through its own source code, and produced the analysis. First finding: Claude Haiku at 0% cache hits. The agent checked the input distribution and found that the average call was ~180 tokens, well below Anthropic’s 4,096-token minimum for Haiku prompt caching. Structurally, these requests could never be cached. They were false positives. The real regression was in Claude Opus: cache hit rate fell from ~70% to ~48% over a week. The agent correlated the drop against the deployment history and traced it to a single PR that restructured prompt ordering, breaking the common prefix that caching relies on. It submitted two fixes: one to exclude all uncacheable requests from the alert, and the other to restore prefix stability in the prompt pipeline. That investigation is how we develop now. We rarely start with dashboards or manual log queries. We start by asking the agent. Three months earlier, it could not have done any of this. The breakthrough was not building better playbooks. It was harness engineering: enabling the agent to discover context as the investigation unfolded. This post is about the architecture decisions that made it possible. Where we started In our last post, Context Engineering for Reliable AI Agents: Lessons from Building Azure SRE Agent, we described how moving to a single generalist agent unlocked more complex investigations. The resolution rates were climbing, and for many internal teams, the agent could now autonomously investigate and mitigate roughly 50% of incidents. We were moving in the right direction. But the scores weren't uniform, and when we dug into why, the pattern was uncomfortable. The high-performing scenarios shared a trait: they'd been built with heavy human scaffolding. They relied on custom response plans for specific incident types, hand-built subagents for known failure modes, and pre-written log queries exposed as opaque tools. We weren’t measuring the agent’s reasoning – we were measuring how much engineering had gone into the scenario beforehand. On anything new, the agent had nowhere to start. We found these gaps through manual review. Every week, engineers read through lower-scored investigation threads and pushed fixes: tighten a prompt, fix a tool schema, add a guardrail. Each fix was real. But we could only review fifty threads a week. The agent was handling ten thousand. We were debugging at human speed. The gap between those two numbers was where our blind spots lived. We needed an agent powerful enough to take this toil off us. An agent which could investigate itself. Dogfooding wasn't a philosophy - it was the only way to scale. The Inversion: Three bets The problem we faced was structural - and the KV cache investigation shows it clearly. The cache rate drop was visible in telemetry, but the cause was not. The agent had to correlate telemetry with deployment history, inspect the relevant code, and reason over the diff that broke prefix stability. We kept hitting the same gap in different forms: logs pointing in multiple directions, failure modes in uninstrumented paths, regressions that only made sense at the commit level. Telemetry showed symptoms, but not what actually changed. We'd been building the agent to reason over telemetry. We needed it to reason over the system itself. The instinct when agents fail is to restrict them: pre-write the queries, pre-fetch the context, pre-curate the tools. It feels like control. In practice, it creates a ceiling. The agent can only handle what engineers anticipated in advance. The answer is an agent that can discover what it needs as the investigation unfolds. In the KV cache incident, each step, from metric anomaly to deployment history to a specific diff, followed from what the previous step revealed. It was not a pre-scripted path. Navigating towards the right context with progressive discovery is key to creating deep agents which can handle novel scenarios. Three architectural decisions made this possible – and each one compounded on the last. Bet 1: The Filesystem as the Agent's World Our first bet was to give the agent a filesystem as its workspace instead of a custom API layer. Everything it reasons over – source code, runbooks, query schemas, past investigation notes – is exposed as files. It interacts with that world using read_file, grep, find, and shell. No SearchCodebase API. No RetrieveMemory endpoint. This is an old Unix idea: reduce heterogeneous resources to a single interface. Coding agents already work this way. It turns out the same pattern works for an SRE agent. Frontier models are trained on developer workflows: navigating repositories, grepping logs, patching files, running commands. The filesystem is not an abstraction layered on top of that prior. It matches it. When we materialized the agent’s world as a repo-like workspace, our human "Intent Met" score - whether the agent's investigation addressed the actual root cause as judged by the on-call engineer - rose from 45% to 75% on novel incidents. But interface design is only half the story. The other half is what you put inside it. Code Repositories: the highest-leverage context Teams had prewritten log queries because they did not trust the agent to generate correct ones. That distrust was justified. Models hallucinate table names, guess column schemas, and write queries against the wrong cluster. But the answer was not tighter restriction. It was better grounding. The repo is the schema. Everything else is derived from it. When the agent reads the code that produces the logs, query construction stops being guesswork. It knows the exact exceptions thrown, and the conditions under which each path executes. Stack traces start making sense, and logs become legible. But beyond query grounding, code access unlocked three new capabilities that telemetry alone could not provide: Ground truth over documentation. Docs drift and dashboards show symptoms. The code is what the service actually does. In practice, most investigations only made sense when logs were read alongside implementation. Point-in-time investigation. The agent checks out the exact commit at incident time, not current HEAD, so it can correlate the failure against the actual diffs. That's what cracked the KV cache investigation: a PR broke prefix stability, and the diff was the only place this was visible. Without commit history, you can't distinguish a code regression from external factors. Reasoning even where telemetry is absent. Some code paths are not well instrumented. The agent can still trace logic through source and explain behavior even when logs do not exist. This is especially valuable in novel failure modes – the ones most likely to be missed precisely because no one thought to instrument them. Memory as a filesystem, not a vector store Our first memory system used RAG over past session learnings. It had a circular dependency: a limited agent learned from limited sessions and produced limited knowledge. Garbage in, garbage out. But the deeper problem was retrieval. In SRE Context, embedding similarity is a weak proxy for relevance. “KV cache regression” and “prompt prefix instability” may be distant in embedding space yet still describe the same causal chain. We tried re-ranking, query expansion, and hybrid search. None fixed the core mismatch between semantic similarity and diagnostic relevance. We replaced RAG with structured Markdown files that the agent reads and writes through its standard tool interface. The model names each file semantically: overview.md for a service summary, team.md for ownership and escalation paths, logs.md for cluster access and query patterns, debugging.md for failure modes and prior learnings. Each carry just enough context to orient the agent, with links to deeper files when needed. The key design choice was to let the model navigate memory, not retrieve it through query matching. The agent starts from a structured entry point and follows the evidence toward what matters. RAG assumes you know the right query before you know what you need. File traversal lets relevance emerge as context accumulates. This removed chunking, overlap tuning, and re-ranking entirely. It also proved more accurate, because frontier models are better at following context than embeddings are at guessing relevance. As a side benefit, memory state can be snapshotted periodically. One problem remains unsolved: staleness. When two sessions write conflicting patterns to debugging.md, the model must reconcile them. When a service changes behavior, old entries can become misleading. We rely on timestamps and explicit deprecation notes, but we do not have a systemic solution yet. This is an active area of work, and anyone building memory at scale will run into it. The sandbox as epistemic boundary The filesystem also defines what the agent can see. If something is not in the sandbox, the agent cannot reason about it. We treat that as a feature, not a limitation. Security boundaries and epistemic boundaries are enforced by the same mechanism. Inside that boundary, the agent has full execution: arbitrary bash, python, jq, and package installs through pip or apt. That scope unlocks capabilities we never would have built as custom tools. It opens PRs with gh cli, like the prompt-ordering fix from KV cache incident. It pushes Grafana dashboards, like a cache-hit-rate dashboard we now track by model. It installs domain-specific CLI tools mid-investigation when needed. No bespoke integration required, just a shell. The recurring lesson was simple: a generally capable agent in the right execution environment outperforms a specialized agent with bespoke tooling. Custom tools accumulate maintenance costs. Shell commands compose for free. Bet 2: Context Layering Code access tells the agent what a service does. It does not tell the agent what it can access, which resources its tools are scoped to, or where an investigation should begin. This gap surfaced immediately. Users would ask "which team do you handle incidents for?" and the agent had no answer. Tools alone are not enough. An integration also needs ambient context so the model knows what exists, how it is configured, and when to use it. We fixed this with context hooks: structured context injected at prompt construction time to orient the agent before it takes action. Connectors - what can I access? A manifest of wired systems such as Log Analytics, Outlook, and Grafana, along with their configuration. Repositories - what does this system do? Serialized repo trees, plus files like AGENTS.md, Copilot.md, and CLAUDE.md with team-specific instructions. Knowledge map - what have I learned before? A two-tier memory index with a top-level file linking to deeper scenario-specific files, so the model can drill down only when needed. Azure resource topology - where do things live? A serialized map of relationships across subscriptions, resource groups, and regions, so investigations start in the right scope. Together, these context hooks turn a cold start into an informed one. That matters because a bad early choice does not just waste tokens. It sends the investigation down the wrong trajectory. A capable agent still needs to know what exists, what matters, and where to start. Bet 3: Frugal Context Management Layered context creates a new problem: budget. Serialized repo trees, resource topology, connector manifests, and a memory index fill context fast. Once the agent starts reading source files and logs, complex incidents hit context limits. We needed our context usage to be deliberately frugal. Tool result compression via the filesystem Large tool outputs are expensive because they consume context before the agent has extracted any value from them. In many cases, only a small slice or a derived summary of that output is actually useful. Our framework exposes these results as files to the agent. The agent can then use tools like grep, jq, or python to process them outside the model interface, so that only the final result enters context. The filesystem isn't just a capability abstraction - it's also a budget management primitive. Context Pruning and Auto Compact Long investigations accumulate dead weight. As hypotheses narrow, earlier context becomes noise. We handle this with two compaction strategies. Context Pruning runs mid-session. When context usage crosses a threshold, we trim or drop stale tool calls and outputs - keeping the window focused on what still matters. Auto-Compact kicks in when a session approaches its context limit. The framework summarizes findings and working hypotheses, then resumes from that summary. From the user's perspective, there's no visible limit. Long investigations just work. Parallel subagents The KV cache investigation required reasoning along two independent hypotheses: whether the alert definition was sound, and whether cache behavior had actually regressed. The agent spawned parallel subagents for each task, each operating in its own context window. Once both finished, it merged their conclusions. This pattern generalizes to any task with independent components. It speeds up the search, keeps intermediate work from consuming the main context window, and prevents one hypothesis from biasing another. The Feedback loop These architectural bets have enabled us to close the original scaling gap. Instead of debugging the agent at human speed, we could finally start using it to fix itself. As an example, we were hitting various LLM errors: timeouts, 429s (too many requests), failures in the middle of response streaming, 400s from code bugs that produced malformed payloads. These paper cuts would cause investigations to stall midway and some conversations broke entirely. So, we set up a daily monitoring task for these failures. The agent searches for the last 24 hours of errors, clusters the top hitters, traces each to its root cause in the codebase, and submits a PR. We review it manually before merging. Over two weeks, the errors were reduced by more than 80%. Over the last month, we have successfully used our agent across a wide range of scenarios: Analyzed our user churn rate and built dashboards we now review weekly. Correlated which builds needed the most hotfixes, surfacing flaky areas of the codebase. Ran security analysis and found vulnerabilities in the read path. Helped fill out parts of its own Responsible AI review, with strict human review. Handles customer-reported issues and LiveSite alerts end to end. Whenever it gets stuck, we talk to it and teach it, ask it to update its memory, and it doesn't fail that class of problem again. The title of this post is literal. The agent investigating itself is not a metaphor. It is a real workflow, driven by scheduled tasks, incident triggers, and direct conversations with users. What We Learned We spent months building scaffolding to compensate for what the agent could not do. The breakthrough was removing it. Every prewritten query was a place we told the model not to think. Every curated tool was a decision made on its behalf. Every pre-fetched context was a guess about what would matter before we understood the problem. The inversion was simple but hard to accept: stop pre-computing the answer space. Give the model a structured starting point, a filesystem it knows how to navigate, context hooks that tell it what it can access, and budget management that keeps it sharp through long investigations. The agent that investigates itself is both the proof and the product of this approach. It finds its own bugs, traces them to root causes in its own code, and submits its own fixes. Not because we designed it to. Because we designed it to reason over systems, and it happens to be one. We are still learning. Staleness is unsolved, budget tuning remains largely empirical, and we regularly discover assumptions baked into context that quietly constrain the agent. But we have crossed a new threshold: from an agent that follows your playbook to one that writes the next one. Thanks to visagarwal for co-authoring this post.
