Azure Functions Documentation

Introduction to Azure Functions

Azure Functions is a serverless compute service that enables you to run event-driven code without explicitly provisioning or managing infrastructure. You pay only for the time your code runs, and can automatically scale based on demand.

Functions are a great way to build small, event-driven pieces of code that respond to a variety of cloud events. They are designed to be highly scalable and cost-effective, making them ideal for a wide range of applications, from simple APIs to complex data processing pipelines.

Key Benefit: Focus on writing code, not managing servers.

Getting Started

To start with Azure Functions, you'll need an Azure subscription. You can create one for free. Once you have an account, you can create your first function using the Azure portal, Azure CLI, or Visual Studio Code with the Azure Functions extension.

Here's a simplified workflow:

  1. Create a Function App: A Function App is a logical collection of functions.
  2. Choose a Trigger: A trigger defines how your function is invoked (e.g., HTTP request, timer, Azure Queue Storage message).
  3. Write Your Code: Implement your business logic in a supported language.
  4. Deploy: Deploy your function to Azure.

For local development, you can use the Azure Functions Core Tools to test your functions before deploying them.

# Example: Install Azure Functions Core Tools
npm install -g azure-functions-core-tools@4 --unsafe-perm true

Core Concepts

Understanding these core concepts is crucial for effectively using Azure Functions.

Triggers

A trigger is what initiates the execution of a function. It defines how a function is activated. Common triggers include:

  • HTTP Trigger: Invoked by an HTTP request.
  • Timer Trigger: Runs on a schedule defined by a CRON expression.
  • Queue Trigger: Activated by a message appearing in an Azure Storage Queue.
  • Blob Trigger: Executed when a blob is added or updated in Azure Blob Storage.
  • Event Grid Trigger: Responds to events published to Azure Event Grid.

Bindings

Bindings allow you to declaratively connect your function code to other Azure services or external data sources without writing complex integration code. They can be used for input, output, or both.

Examples include:

  • Input Bindings: Read data from services like Azure Cosmos DB or Azure Table Storage.
  • Output Bindings: Write data to services like SendGrid (for emails) or Service Bus.

This separation of concerns makes your function code cleaner and easier to manage.

Runtime

Azure Functions runs on a scalable, event-driven runtime. You can choose from different hosting plans that affect scalability, cost, and performance.

Consumption Plan

This is the default and most cost-effective plan for many scenarios. You pay for compute time consumed and the number of executions. The platform automatically scales your functions based on incoming events.

Ideal for event-driven workloads with variable traffic.

Premium Plan

Offers pre-warmed instances for zero cold starts, VNet connectivity, and longer execution times, at a higher cost than the Consumption plan.

App Service Plan

Allows you to run Functions on the same infrastructure as your App Service apps. This provides predictable costs and dedicated resources but lacks auto-scaling and the pay-per-execution model.

Supported Programming Languages

Azure Functions supports a wide range of popular programming languages, allowing you to use your preferred tools and frameworks:

  • C#
  • JavaScript
  • TypeScript
  • Python
  • Java
  • PowerShell
  • Custom Handlers (for any language)

Each language has specific runtime versions and development best practices. Refer to the official documentation for detailed guidance on language-specific features and configurations.

Deployment Options

You have flexible options for deploying your Azure Functions:

  • Azure Portal: Quick deployments for simple functions.
  • Azure CLI: Scriptable deployments for automation.
  • Azure DevOps & GitHub Actions: CI/CD pipelines for continuous integration and delivery.
  • Visual Studio & Visual Studio Code: Integrated development environments with deployment capabilities.
  • Container Deployment: Package your functions as Docker containers for greater control and portability.

Choosing the right deployment strategy depends on your project's complexity and your team's workflow.

Monitoring and Logging

Effective monitoring is essential for understanding your function's performance, identifying errors, and troubleshooting issues.

  • Application Insights: Integrates deeply with Azure Functions to provide detailed telemetry, logs, and performance metrics.
  • Azure Monitor: A comprehensive monitoring solution for Azure resources, including Functions.
  • Log Streaming: View real-time logs from your functions.

Key metrics to monitor include execution count, success/failure rates, response times, and resource utilization.

Security Best Practices

Securing your Azure Functions is paramount:

  • Authentication and Authorization: Implement appropriate mechanisms for HTTP-triggered functions, such as API keys, Azure AD, or OAuth.
  • Managed Identities: Use managed identities to grant your functions secure access to other Azure resources without managing credentials.
  • Secrets Management: Store sensitive information (like connection strings or API keys) in Azure Key Vault.
  • Network Security: Configure VNet integration and private endpoints for enhanced network isolation.
Never hardcode secrets directly in your function code.

Hands-on Tutorials

Explore these tutorials to gain practical experience with Azure Functions: