Getting Started with Azure Functions for Developers

What are Azure Functions?

Azure Functions is a serverless compute service that lets you run code without provisioning or managing infrastructure. You pay only for the time your code runs and can scale automatically from seconds to minutes.

It's ideal for:

• Event-driven computations
• Building APIs and microservices
• Real-time stream processing
• Scheduled tasks

Key Concepts

• Functions: Small pieces of code that respond to events.
• Triggers: Events that cause a function to execute (e.g., HTTP request, timer, queue message).
• Bindings: Declarative ways to connect functions to other Azure services and external data sources, simplifying input and output management.
• Runtime: The environment where your functions execute, supporting multiple programming languages.

Supported Languages

Azure Functions supports a variety of popular programming languages, including:

C# Python Java JavaScript TypeScript PowerShell

Getting Started: A Simple HTTP Trigger Function

Let's create a basic "Hello, World!" HTTP-triggered function.

Prerequisites

• Azure Subscription: Sign up for free
• Azure Functions Core Tools: Install
• A code editor (like VS Code with the Azure Functions extension)

Steps

1. Create a new Functions project: Open your terminal or command prompt and run:

   func init MyFunctionProj --worker-runtime 

   Replace <your-runtime> with your preferred language runtime (e.g., dotnet, python, node).
2. Create a new HTTP Trigger function: Navigate into your project directory and run:

   cd MyFunctionProj

   func new --template "HTTP trigger" --name HttpExample

3. Write your function code: Open the generated function file (e.g., HttpExample/index.js for Node.js, HttpExample.cs for .NET).

   Example (JavaScript):

   
   module.exports = async function (context, req) {
       context.log('JavaScript HTTP trigger function processed a request.');
   
       const name = (req.query.name || (req.body && req.body.name));
       const responseMessage = name
           ? "Hello, " + name + ". This HTTP triggered function executed successfully!"
           : "This HTTP triggered function executed successfully. Pass a name in the query string or in the request body for a personalized response.";
   
       context.res = {
           status: 200,
           body: responseMessage
       };
   };
                           

4. Run your function locally:

   func start

   The output will show the local URL for your HTTP trigger (usually http://localhost:7071/api/HttpExample).
5. Test your function: Open your browser and navigate to the local URL, optionally adding a query parameter: http://localhost:7071/api/HttpExample?name=AzureUser You should see a personalized greeting.

Deploying to Azure

Once you've developed and tested your function locally, you can deploy it to Azure.

You can deploy using:

• Azure Functions Core Tools CLI: func azure functionapp publish <your-function-app-name>
• VS Code Azure Functions extension
• Azure CLI
• ARM templates or Bicep

Check out the official documentation for detailed deployment instructions.