Getting Started with Azure Functions

Published: 2023-10-27 Updated: 2023-10-27 Author: Microsoft Docs

Azure Functions is a serverless compute service that enables you to run event-driven code without explicitly provisioning or managing infrastructure. This guide will walk you through the essential steps to get started with Azure Functions.

What are Azure Functions?

Azure Functions allow you to build applications by running small pieces of code, called "functions," in a cloud environment. These functions can be triggered by various events, such as HTTP requests, timer schedules, or messages from other Azure services. This event-driven model simplifies development and allows you to scale your applications automatically.

Key Concepts

  • Triggers: An Azure resource that defines how a function is invoked. A function must have exactly one trigger.
  • Bindings: A declarative way to connect to other Azure services or data sources without writing complex integration code. Bindings can be input bindings, output bindings, or trigger bindings.
  • Runtime: The environment in which your functions execute. Azure Functions supports multiple programming languages, including C#, JavaScript, Python, Java, and PowerShell.
  • Consumption Plan: A cost-effective pricing model where you pay only for the compute time you consume.
  • Premium Plan: Offers enhanced features like VNet connectivity and always-on instances for predictable performance.

Prerequisites

Before you begin, ensure you have the following installed:

Creating Your First Azure Function

Let's create a simple HTTP-triggered function.

1. Initialize a New Project

Open your terminal or command prompt and run the following command to create a new Functions project:

func init MyFunctionApp --worker-runtime node --docker

This command creates a new directory named MyFunctionApp, initializes it as an Azure Functions project using Node.js as the runtime, and includes Docker support.

2. Add a New Function

Navigate into your project directory and add a new HTTP-triggered function:

cd MyFunctionApp
func new --name HttpTrigger --template "HTTP trigger" --authlevel "anonymous"

This will create a new function named HttpTrigger with an anonymous authentication level, meaning it can be called without a key.

3. Understand the Function Code

Open the generated HttpTrigger/index.js file. You'll see code similar to this:

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. 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
    };
};

This function logs a message, checks for a name parameter in the query string or request body, and returns a personalized greeting.

Pro Tip: For different languages, the structure and syntax will vary. Refer to the official Azure Functions programming model documentation.

4. Run the Function Locally

To run your function locally, use the Azure Functions Core Tools:

func start

The output will show the URL where your HTTP-triggered function is available. Typically, it will be something like http://localhost:7071/api/HttpTrigger.

5. Test Your Function

Open your web browser or use a tool like cURL to send a request to the local URL:

  • Without a name: http://localhost:7071/api/HttpTrigger
  • With a name in the query string: http://localhost:7071/api/HttpTrigger?name=World

You should see the response from your function.

Deploying to Azure

Once you're satisfied with your local function, you can deploy it to Azure.

1. Create an Azure Function App

You can create a Function App via the Azure portal or using the Azure CLI. For example, using the CLI:

az functionapp create --resource-group MyResourceGroup --consumption-plan-location eastus --runtime node --functions-version 4 --name MyUniqueFunctionAppName

Replace MyResourceGroup, eastus, and MyUniqueFunctionAppName with your desired values.

2. Deploy Your Code

From your project directory, deploy using the Core Tools:

func azure functionapp publish MyUniqueFunctionAppName

Follow the prompts to log in to your Azure account if necessary.

Next Steps

Congratulations! You've created and deployed your first Azure Function. Now, explore more advanced topics: