Getting Started with Azure Functions

Azure Functions is a serverless compute service that lets you run small pieces of code, or "functions," without worrying about managing infrastructure. With Azure Functions, you can build applications by running your code in response to events (like HTTP requests, timers, or events from other Azure services) and pay only for the time your code runs.

What are Azure Functions?

Azure Functions is a part of Azure's serverless offering, enabling event-driven programming. Key benefits include:

Cost-Effective: Pay-per-execution model means you only pay when your functions are actively running.
Scalable: Automatically scales based on demand, handling fluctuations in traffic.
Event-Driven: Trigger functions based on a wide range of events.
Polyglot Support: Supports multiple programming languages like C#, Java, JavaScript, PowerShell, Python, and TypeScript.
Integrated Services: Seamless integration with other Azure services and third-party SaaS applications.

Key Concepts

Function: A piece of code that executes in response to a trigger.
Trigger: Defines how a function is invoked. Examples include HTTP triggers, Timer triggers, Blob triggers, Queue triggers, etc.
Binding: Declarative way to connect to data and services without writing complex integration code. Input and output bindings simplify data access.
Runtime: The environment where your functions execute.

Getting Started: Your First Azure Function

Let's create a simple HTTP-triggered function that returns a greeting. We'll use the Azure Functions Core Tools for local development.

Prerequisites

Azure Functions Core Tools installed.
Visual Studio Code with the Azure Functions extension (recommended).
An Azure Account (free tier available).

Steps

Create a new project: Open your terminal or command prompt and run:
```
func init MyFunctionProj --worker-runtime node --language javascript
```
(Replace node and javascript with your preferred runtime if needed, e.g., dotnet, python, java).
Add a new function: Navigate into your project directory and create a new function:
```
cd MyFunctionProj
func new --template "HTTP trigger" --name HttpGreetingFunction
```

Write your function code: Open the HttpGreetingFunction/index.js file and add the following code:

HttpGreetingFunction/index.js
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, /* Defaults to 200 */
        body: responseMessage
    };
};

Run your function locally: In your project directory, run:
```
func start
```
The output will show the local URL for your HTTP trigger (e.g., http://localhost:7071/api/HttpGreetingFunction).
Test your function: Open your browser or use a tool like Postman to send a GET request to the URL with a name parameter: http://localhost:7071/api/HttpGreetingFunction?name=World You should see the response: "Hello, World. This HTTP triggered function executed successfully."

Deploying to Azure

Once you're satisfied with your function, you can deploy it to Azure. The Azure Functions Core Tools and Visual Studio Code provide convenient deployment options.

For detailed deployment instructions and advanced topics like CI/CD, monitoring, and security, please refer to the official Azure Functions documentation.

Create your first function HTTP Bindings Run locally