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.Azure Functions Ignite 2025 Update
Azure Functions is redefining event-driven applications and high-scale APIs in 2025, accelerating innovation for developers building the next generation of intelligent, resilient, and scalable workloads. This year, our focus has been on empowering AI and agentic scenarios: remote MCP server hosting, bulletproofing agents with Durable Functions, and first-class support for critical technologies like OpenTelemetry, .NET 10 and Aspire. With major advances in serverless Flex Consumption, enhanced performance, security, and deployment fundamentals across Elastic Premium and Flex, Azure Functions is the platform of choice for building modern, enterprise-grade solutions. Remote MCP Model Context Protocol (MCP) has taken the world by storm, offering an agent a mechanism to discover and work deeply with the capabilities and context of tools. When you want to expose MCP/tools to your enterprise or the world securely, we recommend you think deeply about building remote MCP servers that are designed to run securely at scale. Azure Functions is uniquely optimized to run your MCP servers at scale, offering serverless and highly scalable features of Flex Consumption plan, plus two flexible programming model options discussed below. All come together using the hardened Functions service plus new authentication modes for Entra and OAuth using Built-in authentication. Remote MCP Triggers and Bindings Extension GA Back in April, we shared a new extension that allows you to author MCP servers using functions with the MCP tool trigger. That MCP extension is now generally available, with support for C#(.NET), Java, JavaScript (Node.js), Python, and Typescript (Node.js). The MCP tool trigger allows you to focus on what matters most: the logic of the tool you want to expose to agents. Functions will take care of all the protocol and server logistics, with the ability to scale out to support as many sessions as you want to throw at it. [Function(nameof(GetSnippet))] public object GetSnippet( [McpToolTrigger(GetSnippetToolName, GetSnippetToolDescription)] ToolInvocationContext context, [BlobInput(BlobPath)] string snippetContent ) { return snippetContent; } New: Self-hosted MCP Server (Preview) If you’ve built servers with official MCP SDKs and want to run them as remote cloud‑scale servers without re‑writing any code, this public preview is for you. You can now self‑host your MCP server on Azure Functions—keep your existing Python, TypeScript, .NET, or Java code and get rapid 0 to N scaling, built-in server authentication and authorization, consumption-based billing, and more from the underlying Azure Functions service. This feature complements the Azure Functions MCP extension for building MCP servers using the Functions programming model (triggers & bindings). Pick the path that fits your scenario—build with the extension or standard MCP SDKs. Either way you benefit from the same scalable, secure, and serverless platform. Use the official MCP SDKs: # MCP.tool() async def get_alerts(state: str) -> str: """Get weather alerts for a US state. Args: state: Two-letter US state code (e.g. CA, NY) """ url = f"{NWS_API_BASE}/alerts/active/area/{state}" data = await make_nws_request(url) if not data or "features" not in data: return "Unable to fetch alerts or no alerts found." if not data["features"]: return "No active alerts for this state." alerts = [format_alert(feature) for feature in data["features"]] return "\n---\n".join(alerts) Use Azure Functions Flex Consumption Plan's serverless compute using Custom Handlers in host.json: { "version": "2.0", "configurationProfile": "mcp-custom-handler", "customHandler": { "description": { "defaultExecutablePath": "python", "arguments": ["weather.py"] }, "http": { "DefaultAuthorizationLevel": "anonymous" }, "port": "8000" } } Learn more about MCPTrigger and self-hosted MCP servers at https://aka.ms/remote-mcp Built-in MCP server authorization (Preview) The built-in authentication and authorization feature can now be used for MCP server authorization, using a new preview option. You can quickly define identity-based access control for your MCP servers with Microsoft Entra ID or other OpenID Connect providers. Learn more at https://aka.ms/functions-mcp-server-authorization. Better together with Foundry agents Microsoft Foundry is the starting point for building intelligent agents, and Azure Functions is the natural next step for extending those agents with remote MCP tools. Running your tools on Functions gives you clean separation of concerns, reuse across multiple agents, and strong security isolation. And with built-in authorization, Functions enables enterprise-ready authentication patterns, from calling downstream services with the agent’s identity to operating on behalf of end users with their delegated permissions. Build your first remote MCP server and connect it to your Foundry agent at https://aka.ms/foundry-functions-mcp-tutorial. Agents Microsoft Agent Framework 2.0 (Public Preview Refresh) We’re excited about the preview refresh 2.0 release of Microsoft Agent Framework that builds on battle hardened work from Semantic Kernel and AutoGen. Agent Framework is an outstanding solution for building multi-agent orchestrations that are both simple and powerful. Azure Functions is a strong fit to host Agent Framework with the service’s extreme scale, serverless billing, and enterprise grade features like VNET networking and built-in auth. Durable Task Extension for Microsoft Agent Framework (Preview) The durable task extension for Microsoft Agent Framework transforms how you build production-ready, resilient and scalable AI agents by bringing the proven durable execution (survives crashes and restarts) and distributed execution (runs across multiple instances) capabilities of Azure Durable Functions directly into the Microsoft Agent Framework. Combined with Azure Functions for hosting and event-driven execution, you can now deploy stateful, resilient AI agents that automatically handle session management, failure recovery, and scaling, freeing you to focus entirely on your agent logic. Key features of the durable task extension include: Serverless Hosting: Deploy agents on Azure Functions with auto-scaling from thousands of instances to zero, while retaining full control in a serverless architecture. Automatic Session Management: Agents maintain persistent sessions with full conversation context that survives process crashes, restarts, and distributed execution across instances Deterministic Multi-Agent Orchestrations: Coordinate specialized durable agents with predictable, repeatable, code-driven execution patterns Human-in-the-Loop with Serverless Cost Savings: Pause for human input without consuming compute resources or incurring costs Built-in Observability with Durable Task Scheduler: Deep visibility into agent operations and orchestrations through the Durable Task Scheduler UI dashboard Create a durable agent: endpoint = os.getenv("AZURE_OPENAI_ENDPOINT") deployment_name = os.getenv("AZURE_OPENAI_DEPLOYMENT_NAME", "gpt-4o-mini") # Create an AI agent following the standard Microsoft Agent Framework pattern agent = AzureOpenAIChatClient( endpoint=endpoint, deployment_name=deployment_name, credential=AzureCliCredential() ).create_agent( instructions="""You are a professional content writer who creates engaging, well-structured documents for any given topic. When given a topic, you will: 1. Research the topic using the web search tool 2. Generate an outline for the document 3. Write a compelling document with proper formatting 4. Include relevant examples and citations""", name="DocumentPublisher", tools=[ AIFunctionFactory.Create(search_web), AIFunctionFactory.Create(generate_outline) ] ) # Configure the function app to host the agent with durable session management app = AgentFunctionApp(agents=[agent]) app.run() Durable Task Scheduler dashboard for agent and agent workflow observability and debugging For more information on the durable task extension for Agent Framework, see the announcement: https://aka.ms/durable-extension-for-af-blog. Flex Consumption Updates As you know, Flex Consumption means serverless without compromise. It combines elastic scale and pay‑for‑what‑you‑use pricing with the controls you expect: per‑instance concurrency, longer executions, VNet/private networking, and Always Ready instances to minimize cold starts. Since launching GA at Ignite 2024 last year, Flex Consumption has had tremendous growth with over 1.5 billion function executions per day and nearly 40 thousand apps. Here’s what’s new for Ignite 2025: 512 MB instance size (GA). Right‑size lighter workloads, scale farther within default quota. Availability Zones (GA). Distribute instances across zones. Rolling updates (Public Preview). Unlock zero-downtime deployments of code or config by setting a single configuration. See below for more information. Even more improvements including: new diagnostic settingsto route logs/metrics, use Key Vault App Config references, new regions, and Custom Handler support. To get started, review Flex Consumption samples, or dive into the documentation to see how Flex can support your workloads. Migrating to Azure Functions Flex Consumption Migrating to Flex Consumption is simple with our step-by-step guides and agentic tools. Move your Azure Functions apps or AWS Lambda workloads, update your code and configuration, and take advantage of new automation tools. With Linux Consumption retiring, now is the time to switch. For more information, see: Migrate Consumption plan apps to the Flex Consumption plan Migrate AWS Lambda workloads to Azure Functions Durable Functions Durable Functions introduces powerful new features to help you build resilient, production-ready workflows: Distributed Tracing: lets you track requests across components and systems, giving you deep visibility into orchestration and activities with support for App Insights and OpenTelemetry. Extended Sessions support in .NET isolated: improves performance by caching orchestrations in memory, ideal for fast sequential activities and large fan-out/fan-in patterns. Orchestration versioning (public preview): enables zero-downtime deployments and backward compatibility, so you can safely roll out changes without disrupting in-flight workflows Durable Task Scheduler Updates Durable Task Scheduler Dedicated SKU (GA): Now generally available, the Dedicated SKU offers advanced orchestration for complex workflows and intelligent apps. It provides predictable pricing for steady workloads, automatic checkpointing, state protection, and advanced monitoring for resilient, reliable execution. Durable Task Scheduler Consumption SKU (Public Preview): The new Consumption SKU brings serverless, pay-as-you-go orchestration to dynamic and variable workloads. It delivers the same orchestration capabilities with flexible billing, making it easy to scale intelligent applications as needed. For more information see: https://aka.ms/dts-ga-blog OpenTelemetry support in GA Azure Functions OpenTelemetry is now generally available, bringing unified, production-ready observability to serverless applications. Developers can now export logs, traces, and metrics using open standards—enabling consistent monitoring and troubleshooting across every workload. Key capabilities include: Unified observability: Standardize logs, traces, and metrics across all your serverless workloads for consistent monitoring and troubleshooting. Vendor-neutral telemetry: Integrate seamlessly with Azure Monitor or any OpenTelemetry-compliant backend, ensuring flexibility and choice. Broad language support: Works with .NET (isolated), Java, JavaScript, Python, PowerShell, and TypeScript. Start using OpenTelemetry in Azure Functions today to unlock standards-based observability for your apps. For step-by-step guidance on enabling OpenTelemetry and configuring exporters for your preferred backend, see the documentation. Deployment with Rolling Updates (Preview) Achieving zero-downtime deployments has never been easier. The Flex Consumption plan now offers rolling updates as a site update strategy. Set a single property, and all future code deployments and configuration changes will be released with zero-downtime. Instead of restarting all instances at once, the platform now drains existing instances in batches while scaling out the latest version to match real-time demand. This ensures uninterrupted in-flight executions and resilient throughput across your HTTP, non-HTTP, and Durable workloads – even during intensive scale-out scenarios. Rolling updates are now in public preview. Learn more at https://aka.ms/functions/rolling-updates. Secure Identity and Networking Everywhere By Design Security and trust are paramount. Azure Functions incorporates proven best practices by design, with full support for managed identity—eliminating secrets and simplifying secure authentication and authorization. Flex Consumption and other plans offer enterprise-grade networking features like VNETs, private endpoints, and NAT gateways for deep protection. The Azure Portal streamlines secure function creation, and updated scenarios and samples showcase these identity and networking capabilities in action. Built-in authentication (discussed above) enables inbound client traffic to use identity as well. Check out our updated Functions Scenarios page with quickstarts or our secure samples gallery to see these identity and networking best practices in action. .NET 10 Azure Functions now supports .NET 10, bringing in a great suite of new features and performance benefits for your code. .NET 10 is supported on the isolated worker model, and it’s available for all plan types except Linux Consumption. As a reminder, support ends for the legacy in-process model on November 10, 2026, and the in-process model is not being updated with .NET 10. To stay supported and take advantage of the latest features, migrate to the isolated worker model. Aspire Aspire is an opinionated stack that simplifies development of distributed applications in the cloud. The Azure Functions integration for Aspire enables you to develop, debug, and orchestrate an Azure Functions .NET project as part of an Aspire solution. Aspire publish directly deploys to your functions to Azure Functions on Azure Container Apps. Aspire 13 includes an updated preview version of the Functions integration that acts as a release candidate with go-live support. The package will be moved to GA quality with Aspire 13.1. Java 25, Node.js 24 Azure Functions now supports Java 25 and Node.js 24 in preview. You can now develop functions using these versions locally and deploy them to Azure Functions plans. Learn how to upgrade your apps to these versions here In Summary Ready to build what’s next? Update your Azure Functions Core Tools today and explore the latest samples and quickstarts to unlock new capabilities for your scenarios. The guided quickstarts run and deploy in under 5 minutes, and incorporate best practices—from architecture to security to deployment. We’ve made it easier than ever to scaffold, deploy, and scale real-world solutions with confidence. The future of intelligent, scalable, and secure applications starts now—jump in and see what you can create!Code Optimizations for Azure App Service Now Available in VS Code
Today we shipped a feature in the Azure App Service extension for VS Code that answers both questions: Code Optimizations, powered by Application Insights profiler data and GitHub Copilot. The problem: production performance is a black box You've deployed your .NET app to Azure App Service. Monitoring shows CPU is elevated, and response times are creeping up. You know something is slow, but reproducing production load patterns locally is nearly impossible. Application Insights can detect these issues, but context-switching between the Azure Portal and your editor to actually fix them adds friction. What if the issues came to you, right where you write code? What's new The Azure App Service extension now adds a Code Optimizations node directly under your .NET web apps in the Azure Resources tree view. This node surfaces performance issues detected by the Application Insights profiler - things like excessive CPU or memory usage caused by specific functions in your code. Each optimization tells you: Which function is the bottleneck Which parent function is calling it What category of resource usage is affected (CPU, memory, etc.) The impact as a percentage, so you can prioritize what matters But we didn't stop at surfacing the data. Click Fix with Copilot on any optimization and the extension will: Locate the problematic code in your workspace by matching function signatures from the profiler stack trace against your local source using VS Code's workspace symbol provider Open the file and highlight the exact method containing the bottleneck Launch a Copilot Chat session pre-filled with a detailed prompt that includes the issue description, the recommendation from Application Insights, the full stack trace context, and the source code of the affected method By including the stack trace, recommendation, impact data, and the actual source code, the prompt gives Copilot enough signal to produce a meaningful, targeted fix rather than generic advice. For example, the profiler might surface a LINQ-heavy data transformation consuming 38% of CPU in OrderService.CalculateTotals, called from CheckoutController.Submit. It then prompts copilot with the problem and it them offers a fix. Prerequisites A .NET web app deployed to Azure App Service Application Insights connected to your app The Application Insights profiler enabled (the extension will prompt you if it's not) For Windows App Service plans When creating a new web app through the extension, you'll now see an option to enable the Application Insights profiler. For existing apps, the Code Optimizations node will guide you through enabling profiling if it's not already active. For Linux App Service plans Profiling on Linux requires a code-level integration rather than a platform toggle. If no issues are found, the extension provides a prompt to help you add profiler support to your application code. What's next This is the first step toward bringing production intelligence directly into the inner development loop. We're exploring how to expand this pattern beyond .NET and beyond performance — surfacing reliability issues, exceptions, and other operational insights where developers can act on them immediately. Install the latest Azure App Service extension and expand the Code Optimizations node under any .NET web app to try it out. We'd love your feedback - file issues on the GitHub repo. Happy Coding <3
Migrating to the next generation of Virtual Nodes on Azure Container Instances (ACI)
What is ACI/Virtual Nodes? Azure Container Instances (ACI) is a fully-managed serverless container platform which gives you the ability to run containers on-demand without provisioning infrastructure. Virtual Nodes on ACI allows you to run Kubernetes pods managed by an AKS cluster in a serverless way on ACI instead of traditional VM‑backed node pools. From a developer’s perspective, Virtual Nodes look just like regular Kubernetes nodes, but under the hood the pods are executed on ACI’s serverless infrastructure, enabling fast scale‑out without waiting for new VMs to be provisioned. This makes Virtual Nodes ideal for bursty, unpredictable, or short‑lived workloads where speed and cost efficiency matter more than long‑running capacity planning. Introducing the next generation of Virtual Nodes on ACI The newer Virtual Nodes v2 implementation modernises this capability by removing many of the limitations of the original AKS managed add‑on and delivering a more Kubernetes‑native, flexible, and scalable experience when bursting workloads from AKS to ACI. In this article I will demonstrate how you can migrate an existing AKS cluster using the Virtual Nodes managed add-on (legacy), to the new generation of Virtual Nodes on ACI, which is deployed and managed via Helm. More information about Virtual Nodes on Azure Container Instances can be found here, and the GitHub repo is available here. Advanced documentation for Virtual Nodes on ACI is also available here, and includes topics such as node customisation, release notes and a troubleshooting guide. Please note that all code samples within this guide are examples only, and are provided without warranty/support. Background Virtual Nodes on ACI is rebuilt from the ground-up, and includes several fixes and enhancements, for instance: Added support/features VNet peering, outbound traffic to the internet with network security groups Init containers Host aliases Arguments for exec in ACI Persistent Volumes and Persistent Volume Claims Container hooks Confidential containers (see supported regions list here) ACI standby pools Support for image pulling via Private Link and Managed Identity (MSI) Planned future enhancements Kubernetes network policies Support for IPv6 Windows containers Port Forwarding Note: The new generation of the add-on is managed via Helm rather than as an AKS managed add-on. Requirements & limitations Each Virtual Nodes on ACI deployment requires 3 vCPUs and 12 GiB memory on one of the AKS cluster’s VMs Each Virtual Nodes node supports up to 200 pods DaemonSets are not supported Virtual Nodes on ACI requires AKS clusters with Azure CNI networking (Kubenet is not supported, nor is overlay networking) Migrating to the next generation of Virtual Nodes on Azure Container Instances via Helm chart For this walkthrough, I'm using Bash via Windows Subsystem for Linux (WSL), along with the Azure CLI. Direct migration is not supported, and therefore the steps below show an example of removing Virtual Nodes managed add-on and its resources and then installing the Virtual Nodes on ACI Helm chart. In this walkthrough I will explain how to delete and re-create the Virtual Nodes subnet, however if you need to preserve the VNet and/or use a custom subnet name, refer to the Helm customisation steps here. Be sure to use a new subnet CIDR within the VNet address space, which doesn't overlap with other subnets nor the AKS CIDRS for nodes/pods and ClusterIP services. To minimise disruption, we'll first install the Virtual Nodes on ACI Helm chart, before then removing the legacy managed add-on and its resources. Prerequisites A recent version of the Azure CLI An Azure subscription with sufficient ACI quota for your selected region Helm Deployment steps Initialise environment variables location=northeurope rg=rg-virtualnode-demo vnetName=vnet-virtualnode-demo clusterName=aks-virtualnode-demo aksSubnetName=subnet-aks vnSubnetName=subnet-vn Create the new Virtual Nodes on ACI subnet with the specific name value of cg (a custom subnet can be used by following the steps here): vnSubnetId=$(az network vnet subnet create \ --resource-group $rg \ --vnet-name $vnetName \ --name cg \ --address-prefixes <your subnet CIDR> \ --delegations Microsoft.ContainerInstance/containerGroups --query id -o tsv) Assign the cluster's -kubelet identity Contributor access to the infrastructure resource group, and Network Contributor access to the ACI subnet: nodeRg=$(az aks show --resource-group $rg --name $clusterName --query nodeResourceGroup -o tsv) nodeRgId=$(az group show -n $nodeRg --query id -o tsv) agentPoolIdentityId=$(az aks show --resource-group $rg --name $clusterName --query "identityProfile.kubeletidentity.resourceId" -o tsv) agentPoolIdentityObjectId=$(az identity show --ids $agentPoolIdentityId --query principalId -o tsv) az role assignment create \ --assignee-object-id "$agentPoolIdentityObjectId" \ --assignee-principal-type ServicePrincipal \ --role "Contributor" \ --scope "$nodeRgId" az role assignment create \ --assignee-object-id "$agentPoolIdentityObjectId" \ --assignee-principal-type ServicePrincipal \ --role "Network Contributor" \ --scope "$vnSubnetId" Download the cluster's kubeconfig file: az aks get-credentials -n $clusterName -g $rg Clone the virtualnodesOnAzureContainerInstances GitHub repo: git clone https://github.com/microsoft/virtualnodesOnAzureContainerInstances.git Install the Virtual Nodes on ACI Helm chart: helm install <yourReleaseName> <GitRepoRoot>/Helm/virtualnode Confirm the Virtual Nodes node shows within the cluster and is in a Ready state (virtualnode-n): $ kubectl get node NAME STATUS ROLES AGE VERSION aks-nodepool1-35702456-vmss000000 Ready <none> 4h13m v1.33.6 aks-nodepool1-35702456-vmss000001 Ready <none> 4h13m v1.33.6 virtualnode-0 Ready <none> 162m v1.33.7 Scale-down any running Virtual Nodes workloads (example below): kubectl scale deploy <deploymentName> -n <namespace> --replicas=0 Drain and cordon the legacy Virtual Nodes node: kubectl drain virtual-node-aci-linux Disable the Virtual Nodes managed add-on (legacy): az aks disable-addons --resource-group $rg --name $clusterName --addons virtual-node Export a backup of the original subnet configuration: az network vnet subnet show --resource-group $rg --vnet-name $vnetName --name $vnSubnetName > subnetConfigOriginal.json Delete the original subnet (subnets cannot be renamed and therefore must be re-created): az network vnet subnet delete -g $rg -n $vnSubnetName --vnet-name $vnetName Delete the previous (legacy) Virtual Nodes node from the cluster: kubectl delete node virtual-node-aci-linux Test and confirm pod scheduling on Virtual Node: apiVersion: v1 kind: Pod metadata: annotations: name: demo-pod spec: containers: - command: - /bin/bash - -c - 'counter=1; while true; do echo "Hello, World! Counter: $counter"; counter=$((counter+1)); sleep 1; done' image: mcr.microsoft.com/azure-cli name: hello-world-counter resources: limits: cpu: 2250m memory: 2256Mi requests: cpu: 100m memory: 128Mi nodeSelector: virtualization: virtualnode2 tolerations: - effect: NoSchedule key: virtual-kubelet.io/provider operator: Exists If the pod successfully starts on the Virtual Node, you should see similar to the below: $ kubectl get pod -o wide demo-pod NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READINESS GATES demo-pod 1/1 Running 0 95s 10.241.0.4 vnode2-virtualnode-0 <none> <none> Modify the nodeSelector and tolerations properties of your Virtual Nodes workloads to match the requirements of Virtual Nodes on ACI (see details below) Modify your deployments to run on Virtual Nodes on ACI For Virtual Nodes managed add-on (legacy), the following nodeSelector and tolerations are used to run pods on Virtual Nodes: nodeSelector: kubernetes.io/role: agent kubernetes.io/os: linux type: virtual-kubelet tolerations: - key: virtual-kubelet.io/provider operator: Exists - key: azure.com/aci effect: NoSchedule For Virtual Nodes on ACI, the nodeSelector/tolerations are slightly different: nodeSelector: virtualization: virtualnode2 tolerations: - effect: NoSchedule key: virtual-kubelet.io/provider operator: Exists Troubleshooting Check the virtual-node-admission-controller and virtualnode-n pods are running within the vn2 namespace: $ kubectl get pod -n vn2 NAME READY STATUS RESTARTS AGE virtual-node-admission-controller-54cb7568f5-b7hnr 1/1 Running 1 (5h21m ago) 5h21m virtualnode-0 6/6 Running 6 (4h48m ago) 4h51m If these pods are in a Pending state, your node pool(s) may not have enough resources available to schedule them (use kubectl describe pod to validate). If the virtualnode-n pod is crashing, check the logs of the proxycri container to see whether there are any Managed Identity permissions issues (the cluster's -agentpool MSI needs to have Contributor access on the infrastructure resource group): kubectl logs -n vn2 virtualnode-0 -c proxycri Further troubleshooting guidance is available within the official documentation. Support If you have issues deploying or using Virtual Nodes on ACI, add a GitHub issue here
Azure SRE Agent Now Builds Expertise Like Your Best Engineer Introducing Deep Context
What if SRE Agent already knew your system before the next incident? Your most experienced SRE didn't become an expert overnight. Day one: reading runbooks, studying architecture diagrams, asking a lot of questions. Month three: knowing which services are fragile, which config changes cascade, which log patterns mean real trouble. Year two: diagnosing a production issue at 2 AM from a single alert because they'd built deep, living context about your systems. That learning process, absorbing documentation, reading code, handling incidents, building intuition from every interaction is what makes an expert. Azure SRE Agent could do the same thing From pulling context to living in it Azure SRE Agent already connects to Azure Monitor, PagerDuty, and ServiceNow. It queries Kusto logs, checks resource health, reads your code, and delivers root cause analysis often resolving incidents without waking anyone up. Thousands of incidents handled. Thousands of engineering hours saved. Deep Context takes this to the next level. Instead of accessing context on demand, your agent now lives in it — continuously reading your code, knowledge building persistent memory from every interaction, and evolving its understanding of your systems in the background. Three things makes Deep Context work: Continuous access. Source code, terminal, Python runtime, and Azure environment are available whenever the agent needs them. Connected repos are cloned into the agent's workspace automatically. The agent knows your code structure from the first message. Persistent memory. Insights from previous investigations, architecture understanding, team context — it all persists across sessions. The next time the agent picks up an alert, it already knows what happened last time. Background intelligence. Even when you're not chatting, background services continuously learn. After every conversation, the agent extracts what worked, what failed, what the root cause was. It aggregates these across all past investigations to build evolving operational insights. The agent recognizes patterns you haven't noticed yet. One example: connected to Kusto, background scanning auto-discovers every table, documents schemas, and builds reusable query templates. But this learning applies broadly — every conversation, every incident, every data source makes the agent sharper. Expertise that compound with every incident New on-call engineer SRE Agent with Deep Context Alert fires Opens runbook, looks up which service this maps to Already knows the service, its dependencies, and failure patterns from prior incidents Investigation Reads logs, searches code, asks teammates Goes straight to the relevant code path, correlates with logs and persistent insights from similar incidents After 100 incidents Becomes the team expert — irreplaceable institutional knowledge Same institutional knowledge — always available, never forgets, scales across your entire organization A human expert takes months to build this depth. An agent with Deep Context builds it in days and the knowledge compounds with every interaction. You shape what your agent learns. Deep Context learns automatically but the best results come when your team actively guides what the agent retains. Type #remember in chat to save important facts your agent should always know environment details, escalation paths, team preferences. For example: "#remember our Redis cache uses Premium tier with 6GB" or "#remember database failover takes approximately 15 minutes." These are recalled automatically during future investigations. Turn investigations into knowledge. After a good investigation, ask your agent to turn the resolution into a runbook: "Create a troubleshooting guide from the steps we just followed and save it to Knowledge settings." The agent generates a structured document, uploads it, and indexes it — so the next time a similar issue occurs, the agent finds and follows that guide automatically. The agent captures insights from every conversation on its own. Your guidance tells it which ones matter most. This is exactly how Microsoft’s own SRE team gets the best results: “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.” Read the full story in The Agent That Investigates Itself. See it in action: an Azure Monitor alert, end to end An HTTP 5xx spike fires on your container app. Your agent is in autonomous mode. It acknowledges the alert, checks resource health, reads logs, and delivers a diagnosis — that's what it already does well. Deep Context makes this dramatically better. Two things change everything: The agent already knows your environment.It'salready read your code, runbooks, and built context from previous investigations. Your route handlers, database layer, deployment configs, operational procedures, it knows all of it. So, when these alert fires, it doesn't start from scratch. It goes straight to the relevant code path, correlates a recent connection pooling commit with the deployment timeline, and confirms the root cause. The agent remembers.It's seen this pattern before a similar incident last week that was investigated but never permanently fixed. It recognizes the recurrence from persistent memory, skips rediscovery, confirms the issue is still in the code, and this time fixes it. Because it's in autonomous mode, the agent edits the source code, restarts the container, pushes the fix to a new branch, creates a PR, opens a GitHub Issue, and verifies service health, all before you wake up. The agent delivers a complete remediation summary including alert, root cause with code references, fix applied, PR created, without a single message from you. Code access turns diagnosis into action. Persistent memory turns recurring problems into solved problems. Give your agent your code — here's why it matters If you're on an IT operations, SRE, or DevOps team, you might think: "Code access? That's for developers." We'd encourage you to rethink that. Your infrastructure-as-code, deployment configs, Helm charts, Terraform files, pipeline definitions — that's all code. And it's exactly the context your agent needs to go from good to extraordinary. When your agent can read your actual configuration and infrastructure code, investigations transform. Instead of generic troubleshooting, you get root cause analysis that points to the exact file, the exact line, the exact config change. It correlates a deployment failure with a specific commit. It reads your Helm values and spots the misconfiguration that caused the pod crash loop. "Will the agent modify our production code?" No. The agent works in a secure sandbox — a copy of your repository, not your production environment. When it identifies a fix, it creates a pull request on a new branch. Your code review process, your CI/CD pipeline, your approval gates — all untouched. The agent proposes. Your team decides. Whether you're a developer, an SRE, or an IT operator managing infrastructure you didn't write — connecting your code is the single highest-impact thing you can do to make your agent smarter. The compound effects Deep Context amplifies every other SRE Agent capability: Deep Context + Incident management → Alerts fire, the agent correlates logs with actual code. Root cause references specific files and line numbers. Deep Context + Scheduled tasks → Automated code analysis, compliance checks, and drift detection — inspecting your actual infrastructure code, not just metrics. Deep Context + MCP connectors → Datadog, Splunk, PagerDuty data combined with source code context. The full picture in one conversation. Deep Context + Knowledge files → Upload runbooks, architecture docs, postmortems — in any format. The agent cross-references your team's knowledge with live code, logs, and infrastructure state. Logs tell the agent what happened. Code tells it why. Your knowledge files tell it what to do about it. Get started Deep Context is available today as part of Azure SRE Agent GA. New agents have it enabled by default. For a step-by-step walkthrough connecting your code, logs, incidents, and knowledge files, see What It Takes to Give an SRE Agent a Useful Starting Point Resources SRE Agent GA Announcement blog - https://aka.ms/sreagent/ga SRE Agent GA What’s new post - https://aka.ms/sreagent/blog/whatsnewGA SRE Agent Documentation – https://aka.ms/sreagent/newdocs SRE Agent Overview - https://aka.ms/sreagent/newdocsoverviewIndustry-Wide Certificate Changes Impacting Azure App Service Certificates
Executive Summary In early 2026, industry-wide changes mandated by browser applications and the CA/B Forum will affect both how TLS certificates are issued as well as their validity period. The CA/B Forum is a vendor body that establishes standards for securing websites and online communications through SSL/TLS certificates. Azure App Service is aligning with these standards for both App Service Managed Certificates (ASMC, free, DigiCert-issued) and App Service Certificates (ASC, paid, GoDaddy-issued). Most customers will experience no disruption. Action is required only if you pin certificates or use them for client authentication (mTLS). Update: February 17, 2026 We’ve published new Microsoft Learn documentation, Industry-wide certificate changes impacting Azure App Service , which provides more detailed guidance on these compliance-driven changes. The documentation also includes additional information not previously covered in this blog, such as updates to domain validation reuse, along with an expanding FAQ section. The Microsoft Learn documentation now represents the most complete and up-to-date overview of these changes. Going forward, any new details or clarifications will be published there, and we recommend bookmarking the documentation for the latest guidance. Who Should Read This? App Service administrators Security and compliance teams Anyone responsible for certificate management or application security Quick Reference: What’s Changing & What To Do Topic ASMC (Managed, free) ASC (GoDaddy, paid) Required Action New Cert Chain New chain (no action unless pinned) New chain (no action unless pinned) Remove certificate pinning Client Auth EKU Not supported (no action unless cert is used for mTLS) Not supported (no action unless cert is used for mTLS) Transition from mTLS Validity No change (already compliant) Two overlapping certs issued for the full year None (automated) If you do not pin certificates or use them for mTLS, no action is required. Timeline of Key Dates Date Change Action Required Mid-Jan 2026 and after ASMC migrates to new chain ASMC stops supporting client auth EKU Remove certificate pinning if used Transition to alternative authentication if the certificate is used for mTLS Mar 2026 and after ASC validity shortened ASC migrates to new chain ASC stops supporting client auth EKU Remove certificate pinning if used Transition to alternative authentication if the certificate is used for mTLS Actions Checklist For All Users Review your use of App Service certificates. If you do not pin these certificates and do not use them for mTLS, no action is required. If You Pin Certificates (ASMC or ASC) Remove all certificate or chain pinning before their respective key change dates to avoid service disruption. See Best Practices: Certificate Pinning. If You Use Certificates for Client Authentication (mTLS) Switch to an alternative authentication method before their respective key change dates to avoid service disruption, as client authentication EKU will no longer be supported for these certificates. See Sunsetting the client authentication EKU from DigiCert public TLS certificates. See Set Up TLS Mutual Authentication - Azure App Service Details & Rationale Why Are These Changes Happening? These updates are required by major browser programs (e.g., Chrome) and apply to all public CAs. They are designed to enhance security and compliance across the industry. Azure App Service is automating updates to minimize customer impact. What’s Changing? New Certificate Chain Certificates will be issued from a new chain to maintain browser trust. Impact: Remove any certificate pinning to avoid disruption. Removal of Client Authentication EKU Newly issued certificates will not support client authentication EKU. This change aligns with Google Chrome’s root program requirements to enhance security. Impact: If you use these certificates for mTLS, transition to an alternate authentication method. Shortening of Certificate Validity Certificate validity is now limited to a maximum of 200 days. Impact: ASMC is already compliant; ASC will automatically issue two overlapping certificates to cover one year. No billing impact. Frequently Asked Questions (FAQs) Will I lose coverage due to shorter validity? No. For App Service Certificate, App Service will issue two certificates to span the full year you purchased. Is this unique to DigiCert and GoDaddy? No. This is an industry-wide change. Do these changes impact certificates from other CAs? Yes. These changes are an industry-wide change. We recommend you reach out to your certificates’ CA for more information. Do I need to act today? If you do not pin or use these certs for mTLS, no action is required. Glossary ASMC: App Service Managed Certificate (free, DigiCert-issued) ASC: App Service Certificate (paid, GoDaddy-issued) EKU: Extended Key Usage mTLS: Mutual TLS (client certificate authentication) CA/B Forum: Certification Authority/Browser Forum Additional Resources Changes to the Managed TLS Feature Set Up TLS Mutual Authentication Azure App Service Best Practices – Certificate pinning DigiCert Root and Intermediate CA Certificate Updates 2023 Sunsetting the client authentication EKU from DigiCert public TLS certificates Feedback & Support If you have questions or need help, please visit our official support channels or the Microsoft Q&A, where our team and the community can assist you.Beyond the Desktop: The Future of Development with Microsoft Dev Box and GitHub Codespaces
The modern developer platform has already moved past the desktop. We’re no longer defined by what’s installed on our laptops, instead we look at what tooling we can use to move from idea to production. An organisations developer platform strategy is no longer a nice to have, it sets the ceiling for what’s possible, an organisation can’t iterate it's way to developer nirvana if the foundation itself is brittle. A great developer platform shrinks TTFC (time to first commit), accelerates release velocity, and maybe most importantly, helps alleviate everyday frictions that lead to developer burnout. Very few platforms deliver everything an organization needs from a developer platform in one product. Modern development spans multiple dimensions, local tooling, cloud infrastructure, compliance, security, cross-platform builds, collaboration, and rapid onboarding. The options organizations face are then to either compromise on one or more of these areas or force developers into rigid environments that slow productivity and innovation. This is where Microsoft Dev Box and GitHub Codespaces come into play. On their own, each addresses critical parts of the modern developer platform: Microsoft Dev Box provides a full, managed cloud workstation. Dev Box gives developers a consistent, high-performance environment while letting central IT apply strict governance and control. Internally at Microsoft, we estimate that usage of Dev Box by our development teams delivers savings of 156 hours per year per developer purely on local environment setup and upkeep. We have also seen significant gains in other key SPACE metrics reducing context-switching friction and improving build/test cycles. Although the benefits of Dev Box are clear in the results demonstrated by our customers it is not without its challenges. The biggest challenge often faced by Dev Box customers is its lack of native Linux support. At the time of writing and for the foreseeable future Dev Box does not support native Linux developer workstations. While WSL2 provides partial parity, I know from my own engineering projects it still does not deliver the full experience. This is where GitHub Codespaces comes into this story. GitHub Codespaces delivers instant, Linux-native environments spun up directly from your repository. It’s lightweight, reproducible, and ephemeral ideal for rapid iteration, PR testing, and cross-platform development where you need Linux parity or containerized workflows. Unlike Dev Box, Codespaces can run fully in Linux, giving developers access to native tools, scripts, and runtimes without workarounds. It also removes much of the friction around onboarding: a new developer can open a repository and be coding in minutes, with the exact environment defined by the project’s devcontainer.json. That said, Codespaces isn’t a complete replacement for a full workstation. While it’s perfect for isolated project work or ephemeral testing, it doesn’t provide the persistent, policy-controlled environment that enterprise teams often require for heavier workloads or complex toolchains. Used together, they fill the gaps that neither can cover alone: Dev Box gives the enterprise-grade foundation, while Codespaces provides the agile, cross-platform sandbox. For organizations, this pairing sets a higher ceiling for developer productivity, delivering a truly hybrid, agile and well governed developer platform. Better Together: Dev Box and GitHub Codespaces in action Together, Microsoft Dev Box and GitHub Codespaces deliver a hybrid developer platform that combines consistency, speed, and flexibility. Teams can spin up full, policy-compliant Dev Box workstations preloaded with enterprise tooling, IDEs, and local testing infrastructure, while Codespaces provides ephemeral, Linux-native environments tailored to each project. One of my favourite use cases is having local testing setups like a Docker Swarm cluster, ready to go in either Dev Box or Codespaces. New developers can jump in and start running services or testing microservices immediately, without spending hours on environment setup. Anecdotally, my time to first commit and time to delivering “impact” has been significantly faster on projects where one or both technologies provide local development services out of the box. Switching between Dev Boxes and Codespaces is seamless every environment keeps its own libraries, extensions, and settings intact, so developers can jump between projects without reconfiguring or breaking dependencies. The result is a turnkey, ready-to-code experience that maximizes productivity, reduces friction, and lets teams focus entirely on building, testing, and shipping software. To showcase this value, I thought I would walk through an example scenario. In this scenario I want to simulate a typical modern developer workflow. Let's look at a day in the life of a developer on this hybrid platform building an IOT project using Python and React. Spin up a ready-to-go workstation (Dev Box) for Windows development and heavy builds. Launch a Linux-native Codespace for cross-platform services, ephemeral testing, and PR work. Run "local" testing like a Docker Swarm cluster, database, and message queue ready to go out-of-the-box. Switch seamlessly between environments without losing project-specific configurations, libraries, or extensions. 9:00 AM – Morning Kickoff on Dev Box I start my day on my Microsoft Dev Box, which gives me a fully-configured Windows environment with VS Code, design tools, and Azure integrations. I select my teams project, and the environment is pre-configured for me through the Dev Box catalogue. Fortunately for me, its already provisioned. I could always self service another one using the "New Dev Box" button if I wanted too. I'll connect through the browser but I could use the desktop app too if I wanted to. My Tasks are: Prototype a new dashboard widget for monitoring IoT device temperature. Use GUI-based tools to tweak the UI and preview changes live. Review my Visio Architecture. Join my morning stand up. Write documentation notes and plan API interactions for the backend. In a flash, I have access to my modern work tooling like Teams, I have this projects files already preloaded and all my peripherals are working without additional setup. Only down side was that I did seem to be the only person on my stand up this morning? Why Dev Box first: GUI-heavy tasks are fast and responsive. Dev Box’s environment allows me to use a full desktop. Great for early-stage design, planning, and visual work. Enterprise Apps are ready for me to use out of the box (P.S. It also supports my multi-monitor setup). I use my Dev Box to make a very complicated change to my IoT dashboard. Changing the title from "IoT Dashboard" to "Owain's IoT Dashboard". I preview this change in a browser live. (Time for a coffee after this hardwork). The rest of the dashboard isnt loading as my backend isnt running... yet. 10:30 AM – Switching to Linux Codespaces Once the UI is ready, I push the code to GitHub and spin up a Linux-native GitHub Codespace for backend development. Tasks: Implement FastAPI endpoints to support the new IoT feature. Run the service on my Codespace and debug any errors. Why Codespaces now: Linux-native tools ensure compatibility with the production server. Docker and containerized testing run natively, avoiding WSL translation overhead. The environment is fully reproducible across any device I log in from. 12:30 PM – Midday Testing & Sync I toggle between Dev Box and Codespaces to test and validate the integration. I do this in my Dev Box Edge browser viewing my codespace (I use my Codespace in a browser through this demo to highlight the difference in environments. In reality I would leverage the VSCode "Remote Explorer" extension and its GitHub Codespace integration to use my Codespace from within my own desktop VSCode but that is personal preference) and I use the same browser to view my frontend preview. I update the environment variable for my frontend that is running locally in my Dev Box and point it at the port running my API locally on my Codespace. In this case it was a web socket connection and HTTPS calls to port 8000. I can make this public by changing the port visibility in my Codespace. https://fluffy-invention-5x5wp656g4xcp6x9-8000.app.github.dev/api/devices wss://fluffy-invention-5x5wp656g4xcp6x9-8000.app.github.dev/ws This allows me to: Preview the frontend widget on Dev Box, connecting to the backend running in Codespaces. Make small frontend adjustments in Dev Box while monitoring backend logs in Codespaces. Commit changes to GitHub, keeping both environments in sync and leveraging my CI/CD for deployment to the next environment. We can see the Dev Box running local frontend and the Codespace running the API connected to each other, making requests and displaying the data in the frontend! Hybrid advantage: Dev Box handles GUI previews comfortably and allows me to live test frontend changes. Codespaces handles production-aligned backend testing and Linux-native tools. Dev Box allows me to view all of my files in one screen with potentially multiple Codespaces running in browser of VS Code Desktop. Due to all of those platform efficiencies I have completed my days goals within an hour or two and now I can spend the rest of my day learning about how to enable my developers to inner source using GitHub CoPilot and MCP (Shameless plug). The bottom line There are some additional considerations when architecting a developer platform for an enterprise such as private networking and security not covered in this post but these are implementation details to deliver the described developer experience. Architecting such a platform is a valuable investment to deliver the developer platform foundations we discussed at the top of the article. While in this demo I have quickly built I was working in a mono repository in real engineering teams it is likely (I hope) that an application is built of many different repositories. The great thing about Dev Box and Codespaces is that this wouldn’t slow down the rapid development I can achieve when using both. My Dev Box would be specific for the project or development team, pre loaded with all the tools I need and potentially some repos too! When I need too I can quickly switch over to Codespaces and work in a clean isolated environment and push my changes. In both cases any changes I want to deliver locally are pushed into GitHub (Or ADO), merged and my CI/CD ensures that my next step, potentially a staging environment or who knows perhaps *Whispering* straight into production is taken care of. Once I’m finished I delete my Codespace and potentially my Dev Box if I am done with the project, knowing I can self service either one of these anytime and be up and running again! Now is there overlap in terms of what can be developed in a Codespace vs what can be developed in Azure Dev Box? Of course, but as organisations prioritise developer experience to ensure release velocity while maintaining organisational standards and governance then providing developers a windows native and Linux native service both of which are primarily charged on the consumption of the compute* is a no brainer. There are also gaps that neither fill at the moment for example Microsoft Dev Box only provides windows compute while GitHub Codespaces only supports VS Code as your chosen IDE. It's not a question of which service do I choose for my developers, these two services are better together! *Changes have been announced to Dev Box pricing. A W365 license is already required today and dev boxes will continue to be managed through Azure. For more information please see: Microsoft Dev Box capabilities are coming to Windows 365 - Microsoft Dev Box | Microsoft Learn
Modernizing Spring Framework Applications with GitHub Copilot App Modernization
Upgrading Spring Framework applications from version 5 to the latest 6.x line (including 6.2+) enables improved performance, enhanced security, alignment with modern Java releases, and full Jakarta namespace compatibility. The transition often introduces breaking API changes, updated module requirements, and dependency shifts. GitHub Copilot app modernization streamlines this upgrade by analyzing your project, generating targeted changes, and guiding you through the migration. Supported Upgrade Path GitHub Copilot app modernization supports: Upgrading Spring Framework to 6.x, including 6.2+ Migrating from javax to jakarta Aligning transitive dependencies and version constraints Updating build plugins and configurations Identifying deprecated or removed APIs Validating dependency updates and surfacing CVE issues These capabilities align with the Microsoft Learn quickstart for upgrading Java projects with GitHub Copilot app modernization. Project Setup Open your Spring Framework project in Visual Studio Code or IntelliJ IDEA with GitHub Copilot app modernization enabled. The tool works with Maven or Gradle projects and evaluates your existing Spring Framework, Java version, imports, and build configurations. Project Analysis When you trigger the upgrade, GitHub Copilot app modernization: Detects the current Spring Framework version Flags javax imports requiring Jakarta migration Identifies incompatible modules, libraries, and plugins Validates JDK compatibility requirements for Spring Framework 6.x Reviews transitive dependencies impacted by the update This analysis provides the foundation for the upgrade plan generated next. Upgrade Plan Generation GitHub Copilot app modernization produces a structured plan including: Updated Spring Framework version (6.x / 6.2+) Replacements for deprecated or removed APIs jakarta namespace updates Updated build plugins and version constraints JDK configuration adjustments You can review the plan, modify version targets, and confirm actions before the tool applies them. Automated Transformations After approval, GitHub Copilot app modernization applies automated changes such as: Updating Spring Framework module coordinates Rewriting imports from javax.* to jakarta.* Updating libraries required for Spring Framework 6.x Adjusting plugin versions and build logic Recommending fixes for API changes These transformations rely on OpenRewrite‑based rules to modernize your codebase efficiently. Build Fix Iteration Once changes are applied, the tool compiles your project and automatically responds to failures: Captures compilation errors Suggests targeted fixes Rebuilds iteratively This loop continues until the project compiles with Spring Framework 6.x in place. Security & Behavior Checks GitHub Copilot app modernization performs validation steps after the upgrade: Checks for CVEs in updated dependencies Identifies potential behavior changes introduced during the transition Offers optional fixes to address issues This adds confidence before final verification. Expected Output After a Spring Framework 5 → 6.x upgrade, you can expect: Updated module coordinates for Spring Framework 6.x / 6.2 jakarta‑aligned imports across the codebase Updated dependency versions aligned with the new Spring ecosystem Updated plugins and build tool configurations Modernized test stack (JUnit 5) A summary file detailing versions updated, code edits applied, dependencies changed, and items requiring manual review Developer Responsibilities GitHub Copilot app modernization accelerates framework upgrade mechanics, but developers remain responsible for: Running full test suites Reviewing custom components, filters, and validation logic Revisiting security configurations and reactive vs. servlet designs Checking integration points and application semantics post‑migration The tool handles the mechanical modernization work so you can focus on correctness, runtime behavior, and quality assurance. Learn More For prerequisites, setup steps, and the complete Java upgrade workflow, refer to the Microsoft Learn guide: Upgrade a Java Project with Github Copilot App Modernization Install GitHub Copilot app modernization for VS Code and IntelliJ IDEAUpgrade your Java JDK (8, 11, 17, 21, or 25) with GitHub Copilot App Modernization
Developers modernizing Java applications often need to upgrade the Java Development Kit (JDK), update frameworks, align dependencies, or migrate older stacks such as Java EE. GitHub Copilot app modernization dramatically speeds up this process by analyzing your project, identifying upgrade blockers, and generating targeted changes. This post highlights supported upgrade paths and what you can expect when using GitHub Copilot app modernization—optimized for search discoverability rather than deep tutorial content. For complete, authoritative guidance, refer to the official Microsoft Learn quickstart. Supported Upgrade Scenarios GitHub Copilot app modernization supports upgrading: Java Development Kit (JDK) to versions 8, 11, 17, 21, or 25 Spring Boot up to 3.5 Spring Framework up to 6.2+ Java EE → Jakarta EE (up to Jakarta EE 10) JUnit Third‑party dependencies to specified versions Ant → Maven build migrations For the full capabilities list, see the Microsoft Learn quickstart. Prerequisites (VS Code or IntelliJ) To use GitHub Copilot app modernization, you’ll need: GitHub account + GitHub Copilot Free Tier, Pro, Pro+, Business, or Enterprise Visual Studio Code Version 1.101+ GitHub Copilot extension GitHub Copilot app modernization extension Restart after installation IntelliJ IDEA Version 2023.3+ GitHub Copilot plugin 1.5.59+ Restart after installation Recommended: Auto‑approve MCP Tool Annotations under Tools > GitHub Project Requirements Java project using Maven or Gradle Git‑managed Maven access to public Maven Central (if Maven) Gradle wrapper version 5+ Kotlin DSL supported VS Code setting: “Tools enabled” set to true if controlled by your org Selecting a Java Project to Upgrade Open any Java project in: Visual Studio Code IntelliJ IDEA Optional sample projects: Maven: uportal‑messaging Gradle: docraptor‑java Once open, launch GitHub Copilot app modernization using Agent Mode. Running an Upgrade (Example: Java 8 → Java 21) Open GitHub Copilot Chat → Switch to Agent Mode → Run a prompt such as: Upgrade this project to Java 21 You’ll receive: Upgrade Plan JDK version updates Build file changes (Maven/Gradle) Dependency version adjustments Framework upgrade paths, if relevant Automated Transformations GitHub Copilot app modernization applies changes using OpenRewrite‑based transformations. Dynamic Build / Fix Loop The agent iterates: Build Detect failure Fix Retry Until the project builds successfully. Security & Behavior Checks Detects CVEs in upgraded dependencies Flags potential behavior changes Offers optional fixes Final Upgrade Summary Generated as a markdown file containing: Updated JDK level Dependencies changed Code edits made Any remaining CVEs or warnings What You Can Expect in a JDK Upgrade Typical outcomes from upgrading Java 8 → Java 21: Updated build configuration (maven.compiler.release → 21) Removal or replacement of deprecated JDK APIs Updated library versions for Java 21 compatibility Surface warnings for manual review Successfully building project with modern JDK settings GitHub Copilot app modernization accelerates these updates while still leaving space for developer review of runtime or architectural changes. Learn More For the complete, authoritative upgrade workflow—covering setup, capabilities, and the full end‑to‑end process—visit: ➡ Quickstart: Upgrade a Java project with GitHub Copilot app modernization (Microsoft Learn) Install GitHub Copilot app modernization for VS Code and IntelliJ IDEA
