Challenge 02 - Create a Hello World Function

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Introduction

Azure Functions are an integral part of a Serverless architecture. Azure Functions allows you to run small pieces of code (called “functions”) without worrying about application infrastructure. With Azure Functions, the cloud infrastructure provides all the up-to-date servers you need to keep your application running at scale.

The goals of this challenge are to get you familiar with the both the developer tools experience for creating a function, and the Azure Portal experience managing how that function is deployed in Azure.

Description

You can develop, test, and debug an Azure Function using developer tools that simulate the Azure hosting environment on your workstation (or GitHub Codespace). Once a function’s code has been developed and tested locally, it can be published to Azure in a compute resource called a “Function App”. A “Function App” in Azure is a hosting environment where your function code will be published to and made available to be invoked by other processes.

• Create a “Hello World” Azure Function in Visual Studio Code that:
  • Uses an HTTP Trigger
  • Returns “Hello <YourName>!” as an output (with your actual name in place of <YourName>)
  • Use any programming language of your choice.
• Build & Test your sample application locally (or in your GitHub Codespace) by invoking it from a web browser
• Deploy the function into a new Azure Function App in Azure and test it using its public URL

NOTE: The TollBooth application that you will work with for the rest of this hack uses C#. You may find it useful to understand how a basic “Hello World” Azure Function works in C# before you explore the TollBooth application’s code. Optionally, you can also try a “Hello World” in JavaScript, which will be useful in Challenge 06.

NOTE: It is easier to create & manage Azure Functions if you have VS Code “Open Folder” to the folder where you want to the code to live. This is because when using VS Code, the Azure Functions extension for VS Code can only work with one language stack at a time. If you have Azure Functions authored in multiple languages and/or folders, you will need to open a separate VS Code window to the individual folder to work with each language.

NOTE: An empty folder “HelloWorld” is provided with the Resources package (and GitHub Codespace), you can use it to create your new Functions project workspace, or create a new empty folder.

Navigating Folders with VS Code on GitHub Codespaces

When using VS Code in GitHub Codespaces, you can navigate to other folders and open them by:

• Selecting Open Folder from the “hamburger menu” in the upper left corner of the VS Code window.
• Navigate to the folder from the drop down that appears at the top of the VS Code window and click “OK”.
• The Codespace will re-load in the browser, with VS Code opened to the folder you chose.

Success Criteria

• Verify that you are able to open your function in a browser (you need the complete Function URL). You should see a message like: Hello, YourName!
• Understand the basic parts of an Azure Function’s code and how to publish it to an Azure Function App in Azure

Learning Resources

• Functions Overview
• Quickstart: Create a C# function using Visual Studio Code
• Quickstart: Create a JavaScript function using Visual Studio Code
• Complete guide to develop functions on Visual Studio Code, follow this advanced guide.
• How to get the Function URL via the Azure Portal