azure-functions

What this skill does

# Azure Functions Skill

This skill provides expert guidance for Azure Functions. Covers troubleshooting, best practices, decision making, architecture & design patterns, limits & quotas, security, configuration, integrations & coding patterns, and deployment. It combines local quick-reference content with remote documentation fetching capabilities.

## How to Use This Skill

> **IMPORTANT for Agent**: Use the **Category Index** below to locate relevant sections. For categories with line ranges (e.g., `L35-L120`), use `read_file` with the specified lines. For categories with file links (e.g., `[security.md](security.md)`), use `read_file` on the linked reference file

> **IMPORTANT for Agent**: If `metadata.generated_at` is more than 3 months old, suggest the user pull the latest version from the repository. If `mcp_microsoftdocs` tools are not available, suggest the user install it: [Installation Guide](https://github.com/MicrosoftDocs/mcp/blob/main/README.md)

This skill requires **network access** to fetch documentation content:
- **Preferred**: Use `mcp_microsoftdocs:microsoft_docs_fetch` with query string `from=learn-agent-skill`. Returns Markdown.
- **Fallback**: Use `fetch_webpage` with query string `from=learn-agent-skill&accept=text/markdown`. Returns Markdown.

## Category Index

| Category | Lines | Description |
|----------|-------|-------------|
| Troubleshooting | L37-L60 | Diagnosing and fixing Azure Functions runtime errors (AZFD/AZFW codes), storage/config issues, timers, networking, and language-specific (Node.js/Python) deployment and execution problems. |
| Best Practices | L61-L78 | Best practices for coding, performance, reliability, error handling, DI, idempotency, connections, and language-specific (C#, Java, Node.js, Python) patterns in Azure Functions. |
| Decision Making | L79-L99 | Guidance on choosing Functions hosting/runtime models, estimating costs, and planning or executing migrations (plans, runtimes, languages, platforms like AWS Lambda or Express) and key extensions. |
| Architecture & Design Patterns | L100-L105 | Running Functions in Linux containers, Durable Functions design with Azure Storage, and hosting Functions on Azure Container Apps for scalable, container-based architectures. |
| Limits & Quotas | L106-L113 | Details on Functions hosting limits: legacy and Flex Consumption plans, scaling behavior, concurrency and target-based scaling settings, and supported languages/versions. |
| Security | L114-L130 | Securing Azure Functions: encryption at rest, secure storage, keys and identities, networking/VNet/private endpoints, SQL access, MCP servers, and App Service-based security controls. |
| Configuration | L131-L171 | Configuring how Functions apps run and integrate: app/host settings, plans, IP/NAT, runtime versions, local dev tools, monitoring (App Insights/OpenTelemetry), and triggers/bindings setup. |
| Integrations & Coding Patterns | L172-L278 | Configuring Azure Functions triggers/bindings to integrate with databases, messaging, storage, OpenAI, MCP, Dapr, SignalR, Web PubSub, Logic Apps, and other Azure/third‑party services. |
| Deployment | L279-L309 | Deploying and hosting Azure Functions: provisioning plans (Consumption, Flex, Kubernetes, Container Apps), CI/CD (GitHub, Azure Pipelines), containers, slots, runtimes, and migration scenarios. |

### Troubleshooting
| Topic | URL |
|-------|-----|
| Resolve AZFD0001 missing AzureWebJobsStorage setting | https://learn.microsoft.com/en-us/azure/azure-functions/errors-diagnostics/diagnostic-events/azfd0001 |
| Fix AZFD0002 invalid AzureWebJobsStorage value | https://learn.microsoft.com/en-us/azure/azure-functions/errors-diagnostics/diagnostic-events/azfd0002 |
| Troubleshoot AZFD0003 StorageException fetching diagnostics | https://learn.microsoft.com/en-us/azure/azure-functions/errors-diagnostics/diagnostic-events/azfd0003 |
| Resolve AZFD0004 Azure Functions host ID collision | https://learn.microsoft.com/en-us/azure/azure-functions/errors-diagnostics/diagnostic-events/azfd0004 |
| Fix AZFD0005 external startup exception in Functions | https://learn.microsoft.com/en-us/azure/azure-functions/errors-diagnostics/diagnostic-events/azfd0005 |
| Handle AZFD0006 expiring SAS token warnings | https://learn.microsoft.com/en-us/azure/azure-functions/errors-diagnostics/diagnostic-events/azfd0006 |
| Resolve AZFD0007 too many secrets backups | https://learn.microsoft.com/en-us/azure/azure-functions/errors-diagnostics/diagnostic-events/azfd0007 |
| Fix AZFD0008 archive-tier Blob secrets repository | https://learn.microsoft.com/en-us/azure/azure-functions/errors-diagnostics/diagnostic-events/azfd0008 |
| Resolve AZFD0009 unable to parse host.json | https://learn.microsoft.com/en-us/azure/azure-functions/errors-diagnostics/diagnostic-events/azfd0009 |
| Fix AZFD0010 TZ/WEBSITE_TIME_ZONE on Linux Consumption | https://learn.microsoft.com/en-us/azure/azure-functions/errors-diagnostics/diagnostic-events/azfd0010 |
| Resolve AZFD0011 missing FUNCTIONS_WORKER_RUNTIME | https://learn.microsoft.com/en-us/azure/azure-functions/errors-diagnostics/diagnostic-events/azfd0011 |
| Fix AZFD0013 mismatched FUNCTIONS_WORKER_RUNTIME and payload | https://learn.microsoft.com/en-us/azure/azure-functions/errors-diagnostics/diagnostic-events/azfd0013 |
| Resolve AZFD0015 non-CRON timer trigger schedule | https://learn.microsoft.com/en-us/azure/azure-functions/errors-diagnostics/diagnostic-events/azfd0015 |
| Fix AZFW0001 invalid binding attributes in Functions | https://learn.microsoft.com/en-us/azure/azure-functions/errors-diagnostics/net-worker-rules/azfw0001 |
| Handle errors and configure retries in Azure Functions | https://learn.microsoft.com/en-us/azure/azure-functions/functions-bindings-error-pages |
| Resolve common Azure Functions networking issues | https://learn.microsoft.com/en-us/azure/azure-functions/functions-networking-faq |
| Troubleshoot Node.js Azure Functions deployment and runtime issues | https://learn.microsoft.com/en-us/azure/azure-functions/functions-node-troubleshoot |
| Fix 'Azure Functions Runtime is unreachable' storage errors | https://learn.microsoft.com/en-us/azure/azure-functions/functions-recover-storage-account |
| Troubleshoot common issues in Python Azure Functions | https://learn.microsoft.com/en-us/azure/azure-functions/recover-python-functions |
| Diagnose and fix Start/Stop VMs for Azure Functions | https://learn.microsoft.com/en-us/azure/azure-functions/start-stop-v2/troubleshoot |

### Best Practices
| Topic | URL |
|-------|-----|
| Avoid async void in Azure Functions (AZF0001) | https://learn.microsoft.com/en-us/azure/azure-functions/errors-diagnostics/sdk-rules/azf0001 |
| Optimize HttpClient usage in Functions (AZF0002) | https://learn.microsoft.com/en-us/azure/azure-functions/errors-diagnostics/sdk-rules/azf0002 |
| Apply Azure Functions design and coding best practices | https://learn.microsoft.com/en-us/azure/azure-functions/functions-best-practices |
| Handle errors and configure retries in Azure Functions | https://learn.microsoft.com/en-us/azure/azure-functions/functions-bindings-error-pages |
| Implement dependency injection in .NET Azure Functions | https://learn.microsoft.com/en-us/azure/azure-functions/functions-dotnet-dependency-injection |
| Design idempotent Azure Functions for duplicate events | https://learn.microsoft.com/en-us/azure/azure-functions/functions-idempotent |
| Apply core development guidance across Azure Functions languages | https://learn.microsoft.com/en-us/azure/azure-functions/functions-reference |
| Develop Java-based Azure Functions with triggers and bindings | https://learn.microsoft.com/en-us/azure/azure-functions/functions-reference-java |
| Apply Node.js-specific patterns in Azure Functions | https://learn.microsoft.com/en-us/azure/azure-functions/functions-reference-node |
| Implement reliable event processing with Event Hubs and Functions | https://learn.microsoft.com/en-us/azure/azure-functions/f