Expanding the Public Preview of the Azure SRE Agent
We are excited to share that the Azure SRE Agent is now available in public preview for everyone instantly – no sign up required. A big thank you to all our preview customers who provided feedback and helped shape this release! Watching teams put the SRE Agent to work taught us a ton, and we’ve baked those lessons into a smarter, more resilient, and enterprise-ready experience. You can now find Azure SRE Agent directly in the Azure Portal and get started, or use the link below. 📖 Learn more about SRE Agent. 👉 Create your first SRE Agent (Azure login required) What’s New in Azure SRE Agent - October Update The Azure SRE Agent now delivers secure-by-default governance, deeper diagnostics, and extensible automation—built for scale. It can even resolve incidents autonomously by following your team’s runbooks. With native integrations across Azure Monitor, GitHub, ServiceNow, and PagerDuty, it supports root cause analysis using both source code and historical patterns. And since September 1, billing and reporting are available via Azure Agent Units (AAUs). Please visit product documentation for the latest updates. Here are a few highlights for this month: Prioritizing enterprise governance and security: By default, the Azure SRE Agent operates with least-privilege access and never executes write actions on Azure resources without explicit human approval. Additionally, it uses role-based access control (RBAC) so organizations can assign read-only or approver roles, providing clear oversight and traceability from day one. This allows teams to choose their desired level of autonomy from read-only insights to approval-gated actions to full automation without compromising control. Covering the breadth and depth of Azure: The Azure SRE Agent helps teams manage and understand their entire Azure footprint. With built-in support for AZ CLI and kubectl, it works across all Azure services. But it doesn’t stop there—diagnostics are enhanced for platforms like PostgreSQL, API Management, Azure Functions, AKS, Azure Container Apps, and Azure App Service. Whether you're running microservices or managing monoliths, the agent delivers consistent automation and deep insights across your cloud environment. Automating Incident Management: The Azure SRE Agent now plugs directly into Azure Monitor, PagerDuty, and ServiceNow to streamline incident detection and resolution. These integrations let the Agent ingest alerts and trigger workflows that match your team’s existing tools—so you can respond faster, with less manual effort. Engineered for extensibility: The Azure SRE Agent incident management approach lets teams reuse existing runbooks and customize response plans to fit their unique workflows. Whether you want to keep a human in the loop or empower the Agent to autonomously mitigate and resolve issues, the choice is yours. This flexibility gives teams the freedom to evolve—from guided actions to trusted autonomy—without ever giving up control. Root cause, meet source code: The Azure SRE Agent now supports code-aware root cause analysis (RCA) by linking diagnostics directly to source context in GitHub and Azure DevOps. This tight integration helps teams trace incidents back to the exact code changes that triggered them—accelerating resolution and boosting confidence in automated responses. By bridging operational signals with engineering workflows, the agent makes RCA faster, clearer, and more actionable. Close the loop with DevOps: The Azure SRE Agent now generates incident summary reports directly in GitHub and Azure DevOps—complete with diagnostic context. These reports can be assigned to a GitHub Copilot coding agent, which automatically creates pull requests and merges validated fixes. Every incident becomes an actionable code change, driving permanent resolution instead of temporary mitigation. Getting Started Start here: Create a new SRE Agent in the Azure portal (Azure login required) Blog: Announcing a flexible, predictable billing model for Azure SRE Agent Blog: Enterprise-ready and extensible – Update on the Azure SRE Agent preview Product documentation Product home page Community & Support We’d love to hear from you! Please use our GitHub repo to file issues, request features, or share feedback with the teamAnnouncing a flexible, predictable billing model for Azure SRE Agent
Billing for Azure SRE Agent will start on September 1, 2025. Announced at Microsoft Build 2025, Azure SRE Agent is a pre-built AI agent for root cause analysis, uptime improvement, and operational cost reduction. Learn more about the billing model and example scenarios.Reimagining AI Ops with Azure SRE Agent: New Automation, Integration, and Extensibility features
Azure SRE Agent offers intelligent and context aware automation for IT operations. Enhanced by customer feedback from our preview, the SRE Agent has evolved into an extensible platform to automate and manage tasks across Azure and other environments. Built on an Agentic DevOps approach - drawing from proven practices in internal Azure operations - the Azure SRE Agent has already saved over 20,000 engineering hours across Microsoft product teams operations, delivering strong ROI for teams seeking sustainable AIOps. An Operations Agent that adapts to your playbooks Azure SRE Agent is an AI powered operations automation platform that empowers SREs, DevOps, IT operations, and support teams to automate tasks such as incident response, customer support, and developer operations from a single, extensible agent. Its value proposition and capabilities have evolved beyond diagnosis and mitigation of Azure issues, to automating operational workflows and seamless integration with the standards and processes used in your organization. SRE Agent is designed to automate operational work and reduce toil, enabling developers and operators to focus on high-value tasks. By streamlining repetitive and complex processes, SRE Agent accelerates innovation and improves reliability across cloud and hybrid environments. In this article, we will look at what’s new and what has changed since the last update. What’s New: Automation, Integration, and Extensibility Azure SRE Agent just got a major upgrade. From no-code automation to seamless integrations and expanded data connectivity, here’s what’s new in this release: No-code Sub-Agent Builder: Rapidly create custom automations without writing code. Flexible, event-driven triggers: Instantly respond to incidents and operational changes. Expanded data connectivity: Unify diagnostics and troubleshooting across more data sources. Custom actions: Integrate with your existing tools and orchestrate end-to-end workflows via MCP. Prebuilt operational scenarios: Accelerate deployment and improve reliability out of the box. Unlike generic agent platforms, Azure SRE Agent comes with deep integrations, prebuilt tools, and frameworks specifically for IT, DevOps, and SRE workflows. This means you can automate complex operational tasks faster and more reliably, tailored to your organization’s needs. Sub-Agent Builder: Custom Automation, No Code Required Empower teams to automate repetitive operational tasks without coding expertise, dramatically reducing manual workload and development cycles. This feature helps address the need for targeted automation, letting teams solve specific operational pain points without relying on one-size-fits-all solutions. Modular Sub-Agents: Easily create custom sub-agents tailored to your team’s needs. Each sub-agent can have its own instructions, triggers, and toolsets, letting you automate everything from outage response to customer email triage. Prebuilt System Tools: Eliminate the inefficiency of creating basic automation from scratch, and choose from a rich library of hundreds of built-in tools for Azure operations, code analysis, deployment management, diagnostics, and more. Custom Logic: Align automation to your unique business processes by defining your automation logic and prompts, teaching the agent to act exactly as your workflow requires. Flexible Triggers: Automate on Your Terms Invoke the agent to respond automatically to mission-critical events, not wait for manual commands. This feature helps speed up incident response and eliminate missed opportunities for efficiency. Multi-Source Triggers: Go beyond chat-based interactions, and trigger the agent to automatically respond to Incident Management and Ticketing systems like PagerDuty and ServiceNow, Observability Alerting systems like Azure Monitor Alerts, or even on a cron-based schedule for proactive monitoring and best-practices checks. Additional trigger sources such as GitHub issues, Azure DevOps pipelines, email, etc. will be added over time. This means automation can start exactly when and where you need it. Event-Driven Operations: Integrate with your CI/CD, monitoring, or support systems to launch automations in response to real-world events - like deployments, incidents, or customer requests. Vital for reducing downtime, it ensures that business-critical actions happen automatically and promptly. Expanded Data Connectivity: Unified Observability and Troubleshooting Integrate data, enabling comprehensive diagnostics and troubleshooting and faster, more informed decision-making by eliminating silos and speeding up issue resolution. Multiple Data Sources: The agent can now read data from Azure Monitor, Log Analytics, and Application Insights based on its Azure role-based access control (RBAC). Additional observability data sources such as Dynatrace, New Relic, Datadog, and more can be added via the Remote Model Context Protocol (MCP) servers for these tools. This gives you a unified view for diagnostics and automation. Knowledge Integration: Rather than manually detailing every instruction in your prompt, you can upload your Troubleshooting Guide (TSG) or Runbook directly, allowing the agent to automatically create an execution plan from the file. You may also connect the agent to resources like SharePoint, Jira, or documentation repositories through Remote MCP servers, enabling it to retrieve needed files on its own. This approach utilizes your organization’s existing knowledge base, streamlining onboarding and enhancing consistency in managing incidents. Azure SRE Agent is also building multi-agent collaboration by integrating with PagerDuty and Neubird, enabling advanced, cross-platform incident management and reliability across diverse environments. Custom Actions: Automate Anything, Anywhere Extend automation beyond Azure and integrate with any tool or workflow, solving the problem of limited automation scope and enabling end-to-end process orchestration. Out-of-the-Box Actions: Instantly automate common tasks like running azcli, kubectl, creating GitHub issues, or updating Azure resources, reducing setup time and operational overhead. Communication Notifications: The SRE Agent now features built-in connectors for Outlook, enabling automated email notifications, and for Microsoft Teams, allowing it to post messages directly to Teams channels for streamlined communication. Bring Your Own Actions: Drop in your own Remote MCP servers to extend the agent’s capabilities to any custom tool or workflow. Future-proof your agentic DevOps by automating proprietary or emerging processes with confidence. Prebuilt Operations Scenarios Address common operational challenges out of the box, saving teams time and effort while improving reliability and customer satisfaction. Incident Response: Minimize business impact and reduce operational risk by automating detection, diagnosis, and mitigation of your workload stack. The agent has built-in runbooks for common issues related to many Azure resource types including Azure Kubernetes Service (AKS), Azure Container Apps (ACA), Azure App Service, Azure Logic Apps, Azure Database for PostgreSQL, Azure CosmosDB, Azure VMs, etc. Support for additional resource types is being added continually, please see product documentation for the latest information. Root Cause Analysis & IaC Drift Detection: Instantly pinpoint incident causes with AI-driven root cause analysis including automated source code scanning via GitHub and Azure DevOps integration. Proactively detect and resolve infrastructure drift by comparing live cloud environments against source-controlled IaC, ensuring configuration consistency and compliance. Handle Complex Investigations: Enable the deep investigation mode that uses a hypothesis-driven method to analyze possible root causes. It collects logs and metrics, tests hypotheses with iterative checks, and documents findings. The process delivers a clear summary and actionable steps to help teams accurately resolve critical issues. Incident Analysis: The integrated dashboard offers a comprehensive overview of all incidents managed by the SRE Agent. It presents essential metrics, including the number of incidents reviewed, assisted, and mitigated by the agent, as well as those awaiting human intervention. Users can leverage aggregated visualizations and AI-generated root cause analyses to gain insights into incident processing, identify trends, enhance response strategies, and detect areas for improvement in incident management. Inbuilt Agent Memory: The new SRE Agent Memory System transforms incident response by institutionalizing the expertise of top SREs - capturing, indexing, and reusing critical knowledge from past incidents, investigations, and user guidance. Benefit from faster, more accurate troubleshooting, as the agent learns from both successes and mistakes, surfacing relevant insights, runbooks, and mitigation strategies exactly when needed. This system leverages advanced retrieval techniques and a domain-aware schema to ensure every on-call engagement is smarter than the last, reducing mean time to resolution (MTTR) and minimizing repeated toil. Automatically gain a continuously improving agent that remembers what works, avoids past pitfalls, and delivers actionable guidance tailored to the environment. GitHub Copilot and Azure DevOps Integration: Automatically triage, respond to, and resolve issues raised in GitHub or Azure DevOps. Integration with modern development platforms such as GitHub Copilot coding agent increases efficiency and ensures that issues are resolved faster, reducing bottlenecks in the development lifecycle. Ready to get started? Azure SRE Agent home page Product overview Pricing Page Pricing Calculator Pricing Blog Demo recordings Deployment samples What’s Next? Give us feedback: Your feedback is critical - You can Thumbs Up / Thumbs Down each interaction or thread, or go to the “Give Feedback” button in the agent to give us in-product feedback - or you can create issues or just share your thoughts in our GitHub repo at https://github.com/microsoft/sre-agent. We’re just getting started. In the coming months, expect even more prebuilt integrations, expanded data sources, and new automation scenarios. We anticipate continuous growth and improvement throughout our agentic AI platforms and services to effectively address customer needs and preferences. Let us know what Ops toil you want to automate next!Deploying a Bun + Hono + Vite app to Azure App Service
TOC Introduction Local Environment Deployment Conclusion 1. Introduction Anthropic, the company behind Claude, recently acquired the JavaScript runtime startup Bun, marking one of the most significant shifts in the modern JavaScript ecosystem since the arrival of Node.js and Deno. This acquisition signals more than a business move, it represents a strategic consolidation of performance-oriented tooling, developer ergonomics, and the future of AI-accelerated software development. At the center of this momentum lies a powerful trio: Bun, Hono, and Vite. Bun is a next-generation JavaScript runtime that reimagines everything from dependency installation to HTTP servers, bundling, and execution speed. On top of Bun, frameworks like Hono provide an elegant, lightweight approach to building APIs and full web applications. Hono embraces the Web Standard API model while optimizing for speed and minimal footprint. For front-end development, Vite completes the trio. Vite provides lightning-fast local development through native ES modules and an optimized build pipeline. When paired with Bun, the developer experience becomes even smoother, as Bun accelerates not only the dev server but also the entire build process. The result is a full-stack workflow where front-end and back-end both benefit from a consistent, high-performance environment. This article will guide you through deploying a Bun + Hono + Vite application to an Azure Linux Web App. 2. Local Environment The development environment used in this example is a Docker container. All project creation, modification, and testing will take place inside this environment. We will build an application using Bun + Hono + Vite, containing three endpoints: / : The root endpoint, which displays Hello Bun Hono Vite /api/hello : A static endpoint /api/backend : A runtime endpoint executed on the server, returning computed results for the frontend to display Create the Docker development environment This command generates a Bun + Hono + Vite project. docker run --rm -it -v "$PWD":/app -w /app oven/bun:latest bunx create-vite . --template vanilla-ts Follow the prompts as shown in the image and make the appropriate selections. After completing the prompts, the corresponding project files will be created. At this point, you may press Ctrl + C to stop the running Bun server. Next, install Hono: docker run --rm -it -v "$PWD":/app -w /app oven/bun:latest bun add hono Create 4 files and edit 2 files Create .vscode/settings.json This file serves two purposes: To prevent the large node_modules folder from being uploaded during deployment. Uploading it wastes bandwidth and may cause compatibility issues between local and production environments. To disable ORYX BUILD from interfering in the deployment process. We will use a custom startup script to handle all build tasks instead. { "appService.zipIgnorePattern": [ "node_modules{,/**}", ".git{,/**}", ".vscode{,/**}" ], "appService.showBuildDuringDeployPrompt": false } Create vite.config.ts This file configures Vite’s base path to use relative paths instead of absolute paths. Although this does not affect the production environment, it is essential locally when URLs and ports may differ. import { defineConfig } from 'vite'; export default defineConfig({ base: './', }); Create server.ts This file configures backend routing using Hono and sets up the Bun server. It includes several test endpoints, some static, and some executed at runtime. import { Hono } from 'hono'; import { serveStatic } from 'hono/bun'; const app = new Hono(); app.get('/api/hello', (c) => { return c.text('this is api/hello'); }); app.get('/api/backend', (c) => { const result = 1 + 1; return c.json({ message: "this is /api/backend", calc: `1 + 1 = ${result}`, value: result, }); }); app.use('/assets/*', serveStatic({ root: './dist' })); app.use('/*', serveStatic({ root: './dist' })); app.get('/', serveStatic({ path: './dist/index.html' })); const port = Number(process.env.PORT ?? 3000); export default { port, fetch: app.fetch, }; Create startup.sh This script serves several important roles: Remove any node_modules folders or tar archives created by ORYX during deployment Install the Bun runtime Fully take over the ORYX build process Start the Bun server as the final step #!/bin/bash set -e echo "===== Startup script running =====" cd /home/site/wwwroot echo "Cleaning up Oryx-generated node_modules..." if [ -d /node_modules ]; then echo "Removing /node_modules ..." rm -rf /node_modules fi if [ -f node_modules.tar.gz ]; then echo "Removing node_modules.tar.gz ..." rm -f node_modules.tar.gz fi echo "Oryx cleanup complete." export BUN_INSTALL=/home/site/wwwroot/.bun export PATH="$BUN_INSTALL/bin:/home/site/wwwroot/node_modules/.bin:$PATH" export NODE_PATH="/home/site/wwwroot/node_modules" if [ ! -f "$BUN_INSTALL/bin/bun" ]; then echo "Bun not found. Installing..." curl -fsSL https://bun.sh/install | bash else echo "Bun already installed at $BUN_INSTALL" fi echo "Using Bun version:" bun --version echo "Running bun install ..." bun install echo "Running bun run build ..." bun run build echo "Starting server with bun run start ..." bun run start Modify src/main.ts Simplify the default welcome page so it only displays our test text. // src/main.ts document.querySelector<HTMLDivElement>('#app')!.innerHTML = ` <h1>Hello Bun Hono Vite</h1> `; Modify package.json Update the scripts section so that the project uses the newly created server.ts as the server entry point. { "name": "app", "private": true, "version": "0.0.0", "type": "module", "scripts": { "dev:vite": "vite", "build": "vite build", "preview": "vite preview", "start": "bun server.ts" }, "devDependencies": { "typescript": "~5.9.3", "vite": "^7.2.4" }, "dependencies": { "hono": "^4.10.7" } } Build the project locally This command generates a dist directory containing all Vite-built static assets. docker run --rm -it -v "$PWD":/app -w /app oven/bun:latest bun run build Run the server locally for testing docker run --rm -it -v "$PWD":/app -w /app -p 3000:3000 -e PORT=3000 oven/bun:latest bun run start You can press Ctrl + C to stop the server when finished. http://127.0.0.1:3000/ http://127.0.0.1:3000/api/hello http://127.0.0.1:3000/api/backend 3. Deployment We create a Linux Web App with a minimum SKU of Premium. Add Environment Variables SCM_DO_BUILD_DURING_DEPLOYMENT=false Purpose: Prevents the deployment environment from packaging during publish. This must also be set in the deployment environment itself. WEBSITE_RUN_FROM_PACKAGE=false Purpose: Instructs Azure Web App not to run the app from a prepackaged file. ENABLE_ORYX_BUILD=false Purpose: Prevents Azure Web App from building after deployment. All build tasks will instead execute during the startup script. Add Startup Command bash /home/site/wwwroot/startup.sh After that, we can return to VS Code and deploy the project. Once the deployment is complete, wait about five minutes for the build process to finish, and then you can begin testing. / /api/hello /api/backend 4. Conclusion Bun + Hono + Vite form a cohesive ecosystem that embodies the next era of JavaScript development: fast, compact, ergonomic, and deeply aligned with modern infrastructure needs. It is particularly well-suited for AI applications, where latency, concurrency, and rapid iteration matter more than ever. From streaming inference endpoints to vector database integrations, this stack offers the responsiveness and scalability essential for AI-powered systems.Announcing App Service Outbound IPv6 Support in Public Preview
Update 12/3/2025: This post has been updated with the public preview announcement for Linux sites, which were previously not included in this announcement. We are excited to announce the public preview of IPv6 outbound support in App Service for both Windows and Linux sites! Public preview of outbound IPv6 support for multi-tenant apps is supported on all App Service plan SKUs, Functions Consumption, Functions Elastic Premium, and Logic Apps Standard. This is the next announcement in our series of IPv6 related feature work on App Service. General availability of Inbound IPv6 Support on App Service multi-tenant This announcement: IPv6 (dual-stack) non-vnet outbound support (multi-tenant) Backlog - IPv6 vnet outbound support (multi-tenant and App Service Environment v3) Backlog - IPv6 vnet inbound support (App Service Environment v3 - both internal and external) Limitations in public preview While Linux sites require you to opt-in to enable outbound IPv6, Windows sites are enabled by default. Enablement for Linux is done via app settings. App settings are not enforceable by Azure Policy. How it works IPv6 outbound allows you to resolve endpoints to IPv6 addresses and call the IPv6 endpoint. There are no changes required in your code to start using IPv6 compatible endpoints. For Windows sites, this feature is enabled by default. But for Linux sites, opt-in via an app setting is required. See the Linux section later in this blog for details on how to enable it. The first iteration of the implementation does not support virtual network traffic. If your app is integrated with a virtual network and you have application traffic routing, aka "Route All" enabled, you will not be able to resolve or reach IPv6 endpoints. If you are using virtual network integration and disable application traffic routing, you can resolve and reach public IPv6 endpoints directly. Be cautious when changing the routing though as all your public traffic will not be routed through the virtual network at that point. Testing To test IPv6 connectivity, you can use the console. You'll also need an IPv6 capable endpoint. In this case, I took advantage of the general availability of inbound IPv6 on App Service and created a web app (named `ipv6`) with inbound IP mode set to "IPv6" and then called these commands ("-6" is optional, but can be used if the endpoint supports both IPv4 and IPv6): nslookup ipv6.azurewebsites.net curl -6 https://ipv6.azurewebsites.net Important considerations During public preview, Windows and Linux have different default behaviors when dealing with IPv6. Windows For Windows, outbound IPv6 is enabled by default. There are no controls to enable or disable outbound IPv6 for Windows during public preview. Windows will default to IPv4 if the DNS lookup returns both address types. So your app will continue to work without issues with this update. Linux Linux, however, when enabled, defaults to IPv6 if the DNS lookup returns both IPv4 and IPv6 address types. Therefore, sites that were previously working fine might experience issues when outbound IPv6 is enabled. If the DNS of your endpoint resolves to an IPv6 address that does not work, your app will also experience this behavior. Additionally, if you have a firewall or network device that blocks IPv6, or your app is not configured to use IPv6 endpoints, you will experience issues when you enable this feature. To prevent issues with this default behavior, we have made this feature an opt-in for Linux sites. To enable outbound IPv6 for Linux sites, add the app setting `WEBSITE_NETWORK_LINUX_OUTBOUND_DISABLE_IPV6` with a value of `false`. This app setting defaults to true if not provided, and therefore disables outbound IPv6 for the site. So if you want to completely disable IPv6 outbound on Linux, there's nothing needed. If you have apps on Linux where you have endpoints with bad IPv6 configurations, we have added the option to remove IPv6 DNS results for specific FQDNs. In addition to the app setting to enable IPv6, you can add an app setting called `WEBSITE_DNS_SUPPRESS_IPV6_RESULT_FQDNS`. For the value, you can add individual FQDNs comma separated or you can simply add `all` in the value to remove all IPv6 results. Updates coming with GA For GA, rather than relying on app settings, which are not enforceable or auditable by Azure Policy, we will create site properties to replicate the behavior of the Linux app settings to enable/disable the feature as well as suppress specific FQDNs. These site properties will only apply to Linux sites. If you are currently using the app settings, those will still work when we GA. But if you set the site properties, those will always take precedence. We want your feedback! As we continue to evolve App Service to support modern web standards, your feedback is invaluable. Try out IPv6 with your apps and let us know what you think!Azure App Service AI Scenarios: Complete Sample with AI Foundry Integration
This blog demonstrates how to implement AI scenarios on Azure App Service using Azure AI Foundry. It provides a complete sample for developers to integrate conversational AI, reasoning models, structured outputs, and multimodal processing (image and audio) into existing Flask applications. The guide includes quick-start deployment steps with Azure Developer CLI (azd), recommended models like GPT-4o-mini, and best practices for enterprise-grade AI integration. Ideal for developers seeking to modernize web apps with agentic capabilities, OpenAPI-based tools, and secure, scalable AI workflows.Faster Python on Azure Functions with uvloop
Python 3.13+ apps on Azure Functions are now faster by default. By replacing the standard event loop with uvloop, the Functions Python worker delivers higher throughput and lower latency for asynchronous workloads — no code changes required. Introduction Azure Functions powers millions of customer scenarios, from real-time APIs to event-driven automation. For Python developers, scalability often comes down to how efficiently the runtime handles I/O, concurrency, and asynchronous workloads. That’s why, starting with Python 3.13, the Azure Functions Python worker now uses uvloop as its default event loop. Built on top of libuv (the same library behind Node.js), uvloop provides a drop-in replacement for Python’s standard asyncio loop with measurable performance improvements. For customers, this means faster request handling and more responsive serverless applications — without having to update a single line of app code. Why Event Loops Matter The event loop is the backbone of any asynchronous Python application. It schedules coroutines, manages I/O events, and drives concurrency. In serverless workloads like Azure Functions, this loop runs continuously to: Handle incoming HTTP requests Dispatch and complete async tasks (like database queries or service calls) Manage parallel event processing (Event Hubs, Service Bus, etc.) The default Python event loop (UnixSelectorEventLoop) is reliable, but it wasn’t designed for high-throughput scenarios at massive scale. Uvloop, by contrast, is a high-performance reimplementation in Cython that consistently outperforms the built-in loop in both throughput and latency. How It Works in Azure Functions In Python 3.13+, the Azure Functions Python worker sets uvloop as the default event loop policy at startup: import uvloop, asyncio asyncio.set_event_loop_policy(uvloop.EventLoopPolicy()) This means any async workload — whether you’re using async def in your functions, calling external APIs, or parallelizing work with asyncio.gather — benefits immediately from uvloop’s faster scheduling and I/O handling. It is already available in the Functions runtime environment. No configuration changes, no requirements.txt edits, and no feature flags. If you’re running Functions on Python 3.13 or higher, uvloop is already in play. Measuring the Performance Gains We tested uvloop against the existing Unix event loop across several realistic workloads. For testing with Flex Consumption on Azure, the app with no uvloop is on Python 3.12, while the app with uvloop is on Python 3.13. The Flex Consumption app has an instance size of 2048 MB. Results were measured by taking the median of three runs for each test case. Test 1: 10k Requests, 50 Virtual Users Environment Event Loop Average HTTP Request Time (ms) Requests per second % Diff vs unix Local unix 96.95 515 - uvloop 87.99 565 +9.7% Azure unix 54.34 882 - uvloop 51.77 923 +4.8% Test 2: Sustained Load, 100 Virtual Users (5 min) Environment Event Loop Number of Requests Requests per second % Diff vs unix Local unix 157,580 525 - uvloop 167,928 560 +6.4% Azure unix 571,797 1,898 - uvloop 588,458 1,961 +2.9% Test 3: Heavy Concurrency, 500 Virtual Users + 5 async tasks per request Environment Event Loop Number of Requests Requests per second % Diff vs unix Local unix 216,212 720 - uvloop 231,878 772 +7% Azure unix 1,791,600 5,696 - uvloop 1,806,750 6,020 +1% The Unix Event Loop started showing failures in both environments in ~2% of requests. Across the board, uvloop delivered measurable improvements in throughput and latency — especially under high concurrency. Why Only Python 3.13+? While uvloop works with older versions of Python, we rolled it out as the default starting in 3.13 because: It ensured the change was strictly a net positive in performance and stability Easier rollout for all available Azure Functions SKUs, avoiding breaking existing customers Python 3.13 for the Azure Functions Worker introduces a Proxy Worker, so this is an additional performance boost to help with the extra overhead introduced Older runtimes remain on the standard event loop to minimize compatibility risks. Challenges and Lessons Learned Integrating uvloop into the Functions Python worker surfaced a few interesting challenges: Compatibility: Ensuring uvloop worked seamlessly across Linux environments at scale Observability: Updating logs to confirm which event loop policy was active Benchmark design: Testing realistic workloads (HTTP requests, async fan-out) to validate improvements beyond microbenchmarks Through this process, we confirmed uvloop consistently improved throughput and latency without regressions. Future Directions Switching to uvloop is just one step in making Azure Functions Python faster and more scalable. Looking ahead, we’re exploring: Deeper async optimizations: further tuning around asyncio and gRPC handling Serialization improvements: building on work like orjson for faster data processing Cold start performance: reducing startup overhead in Python workers Conclusion By adopting uvloop as the default event loop for Python 3.13+, Azure Functions makes async workloads faster, more reliable, and more scalable — all without requiring customers to change their code. If you’re upgrading to Python 3.13 for your Functions apps, uvloop is already running under the hood to give you better performance out of the box. Further Reading Azure Functions Azure Functions Python Developer Reference Guide Azure Functions Performance Optimizer Azure Functions Python Worker Azure Functions Python Library Azure Loading Testing OverviewCommon Misconceptions When Running Locally vs. Deploying to Azure Linux-based Web Apps
TOC Introduction Environment Variable Build Time Compatible Memory Conclusion 1. Introduction One of the most common issues during project development is the scenario where “the application runs perfectly in the local environment but fails after being deployed to Azure.” In most cases, deployment logs will clearly reveal the problem and allow you to fix it quickly. However, there are also more complicated situations where "due to the nature of the error itself" relevant logs may be difficult to locate. This article introduces several common categories of such problems and explains how to troubleshoot them. We will demonstrate them using Python and popular AI-related packages, as these tend to exhibit compatibility-related behavior. Before you begin, it is recommended that you read Deployment and Build from Azure Linux based Web App | Microsoft Community Hub on how Azure Linux-based Web Apps perform deployments so you have a basic understanding of the build process. 2. Environment Variable Simulating a Local Flask + sklearn Project First, let’s simulate a minimal Flask + sklearn project in any local environment (VS Code in this example). For simplicity, the sample code does not actually use any sklearn functions; it only displays plain text. app.py from flask import Flask app = Flask(__name__) @app.route("/") def index(): return "hello deploy environment variable" if __name__ == "__main__": app.run(host="0.0.0.0", port=8000) We also preset the environment variables required during Azure deployment, although these will not be used when running locally. .deployment [config] SCM_DO_BUILD_DURING_DEPLOYMENT=false As you may know, the old package name sklearn has long been deprecated in favor of scikit-learn. However, for the purpose of simulating a compatibility error, we will intentionally specify the outdated package name. requirements.txt Flask==3.1.0 gunicorn==23.0.0 sklearn After running the project locally, you can open a browser and navigate to the target URL to verify the result. python3 -m venv .venv source .venv/bin/activate pip install -r requirements.txt python app.py Of course, you may encounter the same compatibility issue even in your local environment. Simply running the following command resolves it: export SKLEARN_ALLOW_DEPRECATED_SKLEARN_PACKAGE_INSTALL=True We will revisit this error and its solution shortly. For now, create a Linux Web App running Python 3.12 and configure the following environment variables. We will define Oryx Build as the deployment method. SCM_DO_BUILD_DURING_DEPLOYMENT=false WEBSITE_RUN_FROM_PACKAGE=false ENABLE_ORYX_BUILD=true After deploying the code and checking the Deployment Center, you should see an error similar to the following. From the detailed error message, the cause is clear: sklearn is deprecated and replaced by scikit-learn, so additional compatibility handling is now required by the Python runtime. The error message suggests the following solutions: Install the newer scikit-learn package directly. If your project is deeply coupled to the old sklearn package and cannot be refactored yet, enable compatibility by setting an environment variable to allow installation of the deprecated package. Typically, this type of “works locally but fails on Azure” behavior happens because the deprecated package was installed in the local environment a long time ago at the start of the project, and everything has been running smoothly since. Package compatibility issues like this are very common across various languages on Linux. When a project becomes tightly coupled to an outdated package, you may not be able to upgrade it immediately. In these cases, compatibility workarounds are often the only practical short-term solution. In our example, we will add the environment variable: SKLEARN_ALLOW_DEPRECATED_SKLEARN_PACKAGE_INSTALL=True However, here comes the real problem: This variable is needed during the build phase, but the environment variables set in Azure Portal’s Application Settings only take effect at runtime. So what should we do? The answer is simple, shift the Oryx Build process from build-time to runtime. First, open Azure Portal → Configuration and disable Oryx Build. ENABLE_ORYX_BUILD=false Next, modify the project by adding a startup script. run.sh #!/bin/bash export SKLEARN_ALLOW_DEPRECATED_SKLEARN_PACKAGE_INSTALL=True python -m venv .venv source .venv/bin/activate pip install -r requirements.txt python app.py The startup script works just like the commands you run locally before executing the application. The difference is that you can inject the necessary compatibility environment variables before running pip install or starting the app. After that, return to Azure Portal and add the following Startup Command under Stack Settings. This ensures that your compatibility environment variables and build steps run before the runtime starts. bash run.sh Your overall project structure will now look like this. Once redeployed, everything should work correctly. 3. Build Time Build-Time Errors Caused by AI-Related Packages Many build-time failures are caused by AI-related packages, whose installation processes can be extremely time-consuming. You can investigate these issues by reviewing the deployment logs at the following maintenance URL: https://<YOUR_APP_NAME>.scm.azurewebsites.net/newui Compatible Let’s simulate a Flask + numpy project. The code is shown below. app.py from flask import Flask app = Flask(__name__) @app.route("/") def index(): return "hello deploy compatible" if __name__ == "__main__": app.run(host="0.0.0.0", port=8000) We reuse the same environment variables from the sklearn example. .deployment [config] SCM_DO_BUILD_DURING_DEPLOYMENT=false This time, we simulate the incompatibility between numpy==1.21.0 and Python 3.10. requirements.txt Flask==3.1.0 gunicorn==23.0.0 numpy==1.21.0 We will skip the local execution part and move directly to creating a Linux Web App running Python 3.10. Configure the same environment variables as before, and define the deployment method as runtime build. SCM_DO_BUILD_DURING_DEPLOYMENT=false WEBSITE_RUN_FROM_PACKAGE=false ENABLE_ORYX_BUILD=false After deployment, Deployment Center shows a successful publish. However, the actual website displays an error. At this point, you must check the deployment log files mentioned earlier. You will find two key logs: 1. docker.log Displays real-time logs of the platform creating and starting the container. In this case, you will see that the health probe exceeded the default 230-second startup window, causing container startup failure. This tells us the root cause is container startup timeout. To determine why it timed out, we must inspect the second file. 2. default_docker.log Contains the internal execution logs of the container. Not generated in real time, usually delayed around 15 minutes. Therefore, if docker.log shows a timeout error, wait at least 15 minutes to allow the logs to be written here. In this example, the internal log shows that numpy was being compiled during pip install, and the compilation step took too long. We now have a concrete diagnosis: numpy 1.21.0 is not compatible with Python 3.10, which forces pip to compile from source. The compilation exceeds the platform’s startup time limit (230 seconds) and causes the container to fail. We can verify this by checking numpy’s official site: numpy · PyPI numpy 1.21.0 only provides wheels for cp37, cp38, cp39 but not cp310 (which is python 3.10). Thus, compilation becomes unavoidable. Possible Solutions Set the environment variable WEBSITES_CONTAINER_START_TIME_LIMIT to increase the allowed container startup time. Downgrade Python to 3.9 or earlier. Upgrade numpy to 1.21.0+, where suitable wheels for Python 3.10 are available. In this example, we choose this option. After upgrading numpy to version 1.25.0 (which supports Python 3.10) from specifying in requirements.txt and redeploying, the issue is resolved. numpy · PyPI requirements.txt Flask==3.1.0 gunicorn==23.0.0 numpy==1.25.0 Memory The final example concerns the App Service SKU. AI packages such as Streamlit, PyTorch, and others require significant memory. Any one of these packages may cause the build process to fail due to insufficient memory. The error messages vary widely each time. If you repeatedly encounter unexplained build failures, check Deployment Center or default_docker.log for Exit Code 137, which indicates that the system ran out of memory during the build. The only solution in such cases is to scale up. 4. Conclusion This article introduced several common troubleshooting techniques for resolving Linux Web App issues caused during the build stage. Most of these problems relate to package compatibility, although the symptoms may vary greatly. By understanding the debugging process demonstrated in these examples, you will be better prepared to diagnose and resolve similar issues in future deployments.
