Azure Functions Serverless

Event-driven serverless — HTTP, timers, Cosmos DB, Service Bus, Event Grid triggers. Premium plan for VNet.

AzureIntermediate

Why

Functions run on events without servers — HTTP, timers, Cosmos DB, Service Bus. Consumption: pay per execution, 1M free/mo.

Premium plan: VNet, no cold start, pre-warmed instances.

When

Use for event-driven: webhooks, scheduled jobs, DB triggers. Use App Service for web apps, AKS for containers.

How

1. Create — func new --template "HTTP Trigger" --name MyFn 2. Triggers — HTTP, Timer, Cosmos DB, Service Bus, Event Grid, Blob 3. Bindings — declarative input/output, less code 4. Consumption — pay per exec, scales to zero, cold start 5. Premium — pre-warmed, VNet, no cold start, higher cost 6. Durable Functions — orchestration, stateful workflows 7. Deploy — func azure functionapp publish, or zip deploy 8. Proxies — API gateway lite, route to multiple functions

Example

# HTTP trigger (Node v4 model) import { app } from "@azure/functions"; app.http("hello", { methods: ["GET"], handler: async (req, ctx) => { return { body: { hello: "world" } }; }, }); # Timer trigger — daily 2am app.timer("daily", { schedule: "0 0 2 * * *", handler: async (timer, ctx) => { await runDailyJob(); }, }); # Deploy func azure functionapp publish my-fn-app

Common Problems

⚠Cold start 3-5s on Consumption — use Premium for latency-sensitive
⚠VNet only on Premium/App Service plan — Consumption can't access internal
⚠Binding config verbose — v4 model simpler, prefer over v3

Best Practices

✓Use v4 programming model — cleaner, async, TypeScript-first
✓Premium plan for prod — pre-warmed, VNet, no cold start
✓Durable Functions for orchestration — stateful workflows, retries, timers

FAQ

What is Azure Functions Serverless and what problem does it solve?

Event-driven serverless — HTTP, timers, Cosmos DB, Service Bus, Event Grid triggers. Premium plan for VNet. It lets developers deploy, store, and scale without self-managing infrastructure — a core reference for cloud service selection.

How do I get started with Azure Functions Serverless in 5 minutes?

Two steps to run it: (1) Create — func new --template "HTTP Trigger" --name MyFn; (2) Triggers — HTTP, Timer, Cosmos DB, Service Bus, Event Grid, Blob. Validate on the free tier first, then wire into production.

What is the #1 pitfall with Azure Functions Serverless?

The most frequent issue is: Cold start 3-5s on Consumption — use Premium for latency-sensitive. Run a pre-launch checklist item by item, and add policy/config scanning in CI.

What are the best practices for Azure Functions Serverless?

Best practices for Azure Functions Serverless include: Use v4 programming model — cleaner, async, TypeScript-first; Premium plan for prod — pre-warmed, VNet, no cold start; Durable Functions for orchestration — stateful workflows, retries, timers. The first one — "Use v4 programming model — cleaner, async, TypeScript-first" — should be a team default baked into your IaC templates.

How do I control cost and avoid bill surprises with Azure Functions Serverless?

Three ways to prevent overspend: (1) tag every resource with env/team and enable billing alarms; (2) set budget thresholds to trigger Slack/email alerts; (3) review idle resources in Cost Explorer regularly and clean them up. Most Azure Functions Serverless options offer a free tier — validate within free quota before scaling.