Azure Functions Documentation

Welcome to the official documentation for Azure Functions, a serverless compute service that enables you to run small pieces of code, or "functions," without worrying about infrastructure. This guide provides comprehensive information to help you build, deploy, and manage your serverless applications on Azure.

Introduction to Azure Functions

Azure Functions is an event-driven, serverless compute platform that can also solve complex orchestration problems. It allows developers to write and deploy code without managing infrastructure. Functions can be triggered by a variety of Azure services, third-party services, or even custom requests.

Key benefits of Azure Functions include:

Serverless: No infrastructure to provision or manage.
Event-driven: Code runs in response to events.
Scalable: Automatically scales based on demand.
Cost-effective: Pay only for the compute time you consume.
Polyglot: Supports multiple programming languages.

Getting Started with Azure Functions

To start building with Azure Functions, you'll need an Azure subscription. You can create a free account if you don't have one.

Prerequisites

An Azure subscription.
Azure Functions Core Tools installed locally.
A supported IDE (e.g., Visual Studio Code, Visual Studio).

Steps to create your first function

Use the Azure Functions Core Tools to create a new project.
Define a function with a specific trigger (e.g., HTTP trigger, Timer trigger).
Write your function code in your preferred language.
Test your function locally.
Deploy your function to Azure.

For detailed instructions, refer to the Quickstart guides for your preferred language.

Core Concepts

Understanding these core concepts is crucial for effective use of Azure Functions:

Function App: A logical collection of functions that share the same application settings, management, and hosting plan.
Function: A unit of code that responds to an event.
Trigger: An Azure resource that defines how a function is invoked. There are many types of triggers, including HTTP, timers, queues, and storage events.
Binding: Declarative way to connect function data to other Azure services without writing custom integration code. Bindings are divided into triggers and inputs/outputs.

Triggers and Bindings

Triggers and bindings abstract away the complexities of connecting to other services. They allow you to focus on your business logic.

Common Triggers

HTTP Trigger: Invokes a function via an HTTP request.
Timer Trigger: Invokes a function on a schedule defined by a cron expression.
Blob Trigger: Invokes a function when a blob is added or updated in Azure Blob Storage.
Queue Trigger: Invokes a function when a new message is added to an Azure Storage queue.

Common Bindings

Output Bindings: Allow your function to write data to other services (e.g., writing to a queue, saving to a database).
Input Bindings: Allow your function to read data from other services (e.g., reading from a document in Cosmos DB).

Example: An HTTP-triggered function that reads a blob from Azure Blob Storage and writes a message to an Azure Service Bus queue.

functions.json configuration example:

{
  "scriptFile": "__init__.py",
  "bindings": [
    {
      "authLevel": "function",
      "type": "httpTrigger",
      "direction": "in",
      "name": "req",
      "methods": [
        "get",
        "post"
      ]
    },
    {
      "type": "blob",
      "direction": "in",
      "name": "inputBlob",
      "path": "input/{name}.txt",
      "connection": "AzureWebJobsStorage"
    },
    {
      "type": "http",
      "direction": "out",
      "name": "res"
    },
    {
      "type": "queue",
      "direction": "out",
      "name": "outputQueue",
      "queueName": "myqueue-items",
      "connection": "AzureWebJobsStorage"
    }
  ]
}

Programming Models

Azure Functions supports several programming models and languages:

.NET: C#, F#, PowerShell (using the .NET 6+ model).
JavaScript/TypeScript: For Node.js applications.
Python: Version 3.7 and later.
Java: Version 8 and later.
Go: Version 1.15 and later.
PowerShell: For scripting and automation.

Choose the model and language that best suits your project requirements and team expertise.

Deployment

You can deploy your Azure Functions to Azure in various ways:

Azure CLI: A command-line interface for managing Azure resources.
Azure Portal: Deploy directly from the Azure portal using zip deploy or a code editor.
CI/CD Pipelines: Integrate with Azure DevOps, GitHub Actions, or other CI/CD tools for automated deployments.
Containerization: Deploy functions in Docker containers for consistent environments.

Important: When deploying to Azure, ensure your function app is configured with the appropriate application settings and connection strings for any services it interacts with.

Monitoring Azure Functions

Effective monitoring is key to maintaining the health and performance of your functions.

Tools for Monitoring:

Application Insights: Integrated Application Performance Management (APM) service for monitoring live applications, detecting anomalies, and diagnosing issues.
Azure Monitor Logs: Query logs generated by your functions for detailed insights into execution.
Azure Portal Metrics: Monitor key metrics like function execution count, duration, and errors.

Set up alerts to notify you of critical issues or performance degradation.

Azure Functions Pricing

Azure Functions offers flexible pricing models:

Consumption Plan: You pay only for the time your code runs. Ideal for event-driven workloads with variable traffic.
Premium Plan: Offers pre-warmed instances for low-latency execution and VNet connectivity.
App Service Plan: Run functions on existing App Service plans for predictable costs.

Visit the official Azure Functions pricing page for the most up-to-date information.

Last updated: October 26, 2023