Ultimate Azure Functions

A Claude Code skill for building serverless applications on Microsoft Azure. Covers Azure Functions development with the modern isolated worker model, trigger types, bindings, Durable Functions for orchestration, and deployment with Azure DevOps or GitHub Actions.

When to Use This Skill

Choose Ultimate Azure Functions when:

• You're building serverless applications on Azure
• You need Azure Functions with HTTP, Timer, Queue, or Blob triggers
• You want to implement Durable Functions for workflow orchestration
• You need to set up CI/CD for Azure Functions deployment
• You want to optimize Azure Functions performance and costs

Consider alternatives when:

• You need AWS serverless (use an AWS Serverless skill)
• You want container-based deployment (use a Docker/Kubernetes skill)
• You need general .NET development (use a .NET development skill)

Quick Start

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# Install Azure Functions Core Tools
npm install -g azure-functions-core-tools@4

# Install the skill
claude install ultimate-azure-functions

# Create a Function App
claude "Create an Azure Functions project with TypeScript: HTTP trigger, Timer trigger, and Queue trigger"

# Deploy with GitHub Actions
claude "Set up GitHub Actions deployment for my Azure Functions app to staging and production slots"

Core Concepts

Programming Models

Model	Runtime	Language	Status
Isolated Worker (.NET)	Out-of-process	C#	Recommended
In-Process (.NET)	In-process	C#	Legacy
Node.js v4	Out-of-process	TypeScript/JS	Recommended
Python v2	Out-of-process	Python	Recommended

Trigger Types

Trigger	Fires When	Common Use Case
HTTP	HTTP request received	REST APIs, webhooks
Timer	CRON schedule	Scheduled jobs, cleanup tasks
Queue	Message added to Azure Queue	Async processing
Blob	File uploaded to Blob Storage	File processing, image resize
Cosmos DB	Document changed in Cosmos DB	Change feed processing
Event Grid	Event published	Event-driven architectures
Service Bus	Message received	Enterprise messaging

Node.js v4 HTTP Function

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import { app, HttpRequest, HttpResponseInit } from '@azure/functions';

app.http('getUser', {
  methods: ['GET'],
  authLevel: 'function',
  route: 'users/{id}',
  handler: async (request: HttpRequest): Promise<HttpResponseInit> => {
    const id = request.params.id;
    const user = await getUserById(id);

    return user
      ? { jsonBody: user }
      : { status: 404, jsonBody: { error: 'User not found' } };
  },
});

Configuration

Parameter	Type	Default	Description
runtime	string	"node"	Runtime: node, dotnet, python, java
language	string	"typescript"	Language: typescript, javascript, csharp, python
plan	string	"consumption"	Plan: consumption, premium, dedicated
auth_level	string	"function"	Auth: anonymous, function, admin
deployment	string	"github_actions"	Deploy: github_actions, azure_devops, cli

Best Practices

1. Use the v4 programming model — The v4 model (Node.js) and isolated worker model (.NET) are the modern approach. They provide better dependency injection, middleware support, and testability. Avoid the older in-process model for new projects.

2. Use Consumption plan for unpredictable traffic — Consumption plan scales to zero and you only pay when functions execute. Use Premium plan only if you need VNet integration, no cold starts, or longer execution times.

3. Implement Durable Functions for workflows — For multi-step processes (order processing, approval flows), use Durable Functions instead of chaining regular functions with queues. Durable Functions handle retries, state, and orchestration automatically.

4. Use deployment slots for zero-downtime updates — Deploy to a staging slot, verify, then swap to production. This prevents downtime and allows instant rollback if issues are discovered.

5. Monitor with Application Insights — Enable Application Insights for automatic telemetry. Track custom metrics for business-relevant events. Set up alerts for error rates and performance degradation.

Common Issues

Cold starts on Consumption plan — Pre-warm functions with a Timer trigger that runs every 5 minutes, or upgrade to Premium plan with always-ready instances. Keep function packages small to reduce startup time.

Function timeout after 5 minutes — The default Consumption plan timeout is 5 minutes (max 10). For longer operations, use Durable Functions which can run for days. Alternatively, use a Premium or Dedicated plan with higher timeout limits.

Queue messages processed multiple times — Azure Queue has at-least-once delivery. Implement idempotent processing using the message dequeue count and a processed-messages cache. Check context.retryContext to handle retries gracefully.