Building and deploying Azure Functions with VS Code

Azure Functions is a compute service that allows you to run code on-demand without having to manage infrastructure, making it ideal for processing data, integrating systems, and building simple APIs. It supports a variety of languages such as C#, Java, JavaScript/Node.js, Python, and PowerShell.

In this tutorial, we’ll walk you through the process of building and deploying an Azure Function, using Visual Studio Code as the development environment.

Prerequisites

Before we begin, make sure you have the following:

An Azure account. You can create a free account by visiting azure.com/free.
The Azure Functions extension installed in VS Code. You can install it by opening VS Code and navigating to the Extensions panel on the left-hand side. Search for “Azure Functions” and click Install.

Creating a new Project

To create a new Azure Functions project in VS Code, follow these steps:

Open VS Code and click “File” > “New Folder”. Give the folder a name (e.g. “MyFirstFunction”) and click “Open”.
Open the Terminal panel in VS Code by navigating to “Terminal” > “New Terminal”.
In the terminal, navigate to the folder you just created by typing the following command:
```
cd MyFirstFunction
```
Create a new Azure Functions project by running the following command:
```
func init
```
This command will prompt you to choose a runtime and a development language. Select your preferred options and press Enter.
After the initialization is complete, you’ll see a new folder called “MyFirstFunction” in your project folder. This folder contains a basic project structure with a host.json file, a local.settings.json file, and a folder for your functions.
To create a new function, navigate to the “MyFirstFunction” folder in the Terminal panel and type the following command:
```
func new
```
This will prompt you to select a function template. Choose your preferred language and function type, then press Enter.

We’ll choose the “HttpTrigger” template for this tutorial.
Next, you’ll be prompted to enter a name for your function. Enter a name (e.g. “MyFirstFunction”) and press Enter.
You’ll now see a new file in your “MyFirstFunction” folder called MyFirstFunction/index.js. This is your function code file.

Testing your Function Locally

Now that your function is created, you can test it locally before deploying it to Azure.

In the Terminal panel, navigate to your “MyFirstFunction” folder and run the following command to start the local Azure Functions runtime:
```
func start
```
You’ll see output in the terminal indicating that the runtime has started.
Open your web browser and navigate to http://localhost:7071/api/MyFirstFunction`, replacingMyFirstFunction` with the name of your function.

You should see a message in your browser that says “Please pass a name on the query string or in the request body”.

Let’s modify your function to return a personalized message based on the query string or request body.

Open MyFirstFunction/index.js and replace the contents of the file with the following code:

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
   };
}

This code checks for a name parameter in the query string or request body, and returns a personalized message if it’s present.

Save your changes to index.js, and refresh your browser to test the updated function.

Try adding ?name=yourname to the end of the URL to see the personalized message. You should see a message that says “Hello, yourname. This HTTP triggered function executed successfully.”

This confirms that your function is working as expected.

Deploying your Function to Azure

Now that your function is tested locally, you’re ready to deploy it to Azure.

First, you’ll need to create a new Function App in Azure. Navigate to the Azure portal and click “Create a Resource” > “Compute” > “Function App”.
Fill out the necessary information (subscription, resource group, etc.), and click “Review + Create” to create your Function App.
Once your Function App is created, open it in the Azure portal. Click on “Deployment Center” in the left-hand menu, and choose “Local Git” as the deployment method.

This will create a new Git repository for your Azure Function.
In VS Code, open the Terminal panel and navigate to the root of your project folder.

Initialize a new Git repository by running the following command:
```
git init
```
This will create a new Git repository in your project folder.
Next, add the Azure Functions Git repository as a remote by running the following command:
```
git remote add azure <git-url-from-azure-portal>
```
Replace <git-url-from-azure-portal> with the Git clone URL from the Azure portal.
To deploy your function to Azure, commit your changes to your local Git repository by running the following commands:
```
git add .
git commit -m "Initial commit"
```
Finally, push your changes to the Azure remote by running the following command:
```
git push azure master
```
This will push your local changes to the Azure Git repository and trigger a deployment of your function to Azure.

You can monitor the deployment status in the Azure portal by navigating to your Function App and clicking “Deployment Center” > “Deployment Details”.

Once the deployment is complete, you can test your function in Azure by navigating to your Function App and clicking “Functions” > “MyFirstFunction” (or whatever name you chose for your function).

You’ll see a test page where you can enter a name and test your function.

Congratulations! You’ve successfully created and deployed an Azure Function using Visual Studio Code.

Conclusion

In this tutorial, we walked through the process of creating a new Azure Functions project in VS Code, testing a function locally, and deploying the function to Azure.

Azure Functions simplifies the process of building and deploying code that runs on-demand, making it ideal for a variety of use cases.

With the Azure Functions extension for VS Code, you can streamline your development and deployment process, allowing you to focus on building the functionality of your function.

To learn more about Azure Functions, check out the official documentation at docs.microsoft.com/azure/azure-functions.

Prerequisites

Creating a new Project

Testing your Function Locally

Deploying your Function to Azure

Conclusion

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