What is Azure Functions?

Azure Functions is a serverless compute service that lets you run event-driven code without managing servers. You only pay for the time your code runs.

Key Features

⭐ 1. Event-Driven

Functions can be triggered by:

• HTTP requests

• Timer (CRON schedule)

• Azure Storage (Blob/Queue)

• Event Hub / Service Bus

• Cosmos DB changes

• Event Grid events

⭐ 2. Multiple Languages Supported

• C# (.NET)

• JavaScript / TypeScript

• Python

• Java

• PowerShell

• Go (preview/open-source extension)

⭐ 3. Consumption Based

Pricing models:

• Consumption Plan: Pay per execution, auto-scale

• Premium Plan: Pre-warmed instances, VNET

• Dedicated (App Service): Runs on normal App Service plan

Execution Model

Bindings

Bindings reduce boilerplate code.

Input Bindings

Receive data (e.g., blob, queue message)

Output Bindings

Send data (e.g., write to queue, send to Cosmos DB)

Trigger vs Binding

• Trigger: Starts the function

• Binding: Connects to external services

Scaling

Azure Functions automatically scale based on:

• Number of events

• Trigger type

• Plan (Consumption scales fastest)

Use Cases

• CRON jobs

• Image/file processing

• API backends

• Stream/event processing

• Automation workflows

Pros

• No server management

• Auto-scaling

• Pay-as-you-go

• Fast development

Cons

• Cold start (Consumption plan)

• Execution timeout limits

• Vendor lock-in