Get started on Azure Dev Spaces with .NET Core

In this guide, you will learn how to:

  • Create a Kubernetes-based environment in Azure that is optimized for development - a dev space.
  • Iteratively develop code in containers using VS Code and the command line.
  • Productively develop and test your code in a team environment.

Note

If you get stuck at any time, see the Troubleshooting section.

Install the Azure CLI

Azure Dev Spaces requires minimal local machine setup. Most of your dev space's configuration gets stored in the cloud, and is shareable with other users. Start by downloading and running the Azure CLI.

Sign in to Azure CLI

Sign in to Azure. Type the following command in a terminal window:

az login

Note

If you don't have an Azure subscription, you can create a free account.

If you have multiple Azure subscriptions...

You can view your subscriptions by running:

az account list

Locate the subscription which has isDefault: true in the JSON output. If this isn't the subscription you want to use, you can change the default subscription:

az account set --subscription <subscription ID>

Create a Kubernetes cluster enabled for Azure Dev Spaces

At the command prompt, create the resource group in a region that supports Azure Dev Spaces.

az group create --name MyResourceGroup --location <region>

Create a Kubernetes cluster with the following command:

az aks create -g MyResourceGroup -n MyAKS --location <region> --disable-rbac --generate-ssh-keys

It takes a few minutes to create the cluster.

Configure your AKS cluster to use Azure Dev Spaces

Enter the following Azure CLI command, using the resource group that contains your AKS cluster, and your AKS cluster name. The command configures your cluster with support for Azure Dev Spaces.

az aks use-dev-spaces -g MyResourceGroup -n MyAKS

Important

The Azure Dev Spaces configuration process will remove the azds namespace in the cluster, if it exists.

Get Kubernetes debugging for VS Code

Rich features like Kubernetes debugging are available for .NET Core and Node.js developers using VS Code.

  1. If you don't have it, install VS Code.
  2. Download and install the VS Azure Dev Spaces extension. Click Install once on the extension's Marketplace page, and again in VS Code.

Create a web app running in a container

In this section, you'll create an ASP.NET Core web app and get it running in a container in Kubernetes.

Create an ASP.NET Core web app

Clone or download the Azure Dev Spaces sample application. This article uses the code in the samples/dotnetcore/getting-started/webfrontend directory.

Preparing code for Docker and Kubernetes development

So far, you have a basic web app that can run locally. You'll now containerize it by creating assets that define the app's container and how it will deploy to Kubernetes. This task is easy to do with Azure Dev Spaces:

  1. Launch VS Code and open the webfrontend folder. (You can ignore any default prompts to add debug assets or restore the project.)

  2. Open the Integrated Terminal in VS Code (using the View > Integrated Terminal menu).

  3. Run this command (be sure that webfrontend is your current folder):

    azds prep --public
    

The Azure CLI's azds prep command generates Docker and Kubernetes assets with default settings:

  • ./Dockerfile describes the app's container image, and how the source code is built and runs within the container.
  • A Helm chart under ./charts/webfrontend describes how to deploy the container to Kubernetes.

For now, it isn't necessary to understand the full content of these files. It's worth pointing out, however, that the same Kubernetes and Docker configuration-as-code assets can be used from development through to production, thus providing better consistency across different environments.

A file named ./azds.yaml is also generated by the prep command, and it is the configuration file for Azure Dev Spaces. It complements the Docker and Kubernetes artifacts with additional configuration that enables an iterative development experience in Azure.

Build and run code in Kubernetes

Let's run our code! In the terminal window, run this command from the root code folder, webfrontend:

azds up

Keep an eye on the command's output, you'll notice several things as it progresses:

  • Source code is synced to the dev space in Azure.
  • A container image is built in Azure, as specified by the Docker assets in your code folder.
  • Kubernetes objects are created that utilize the container image as specified by the Helm chart in your code folder.
  • Information about the container's endpoint(s) is displayed. In our case, we're expecting a public HTTP URL.
  • Assuming the above stages complete successfully, you should begin to see stdout (and stderr) output as the container starts up.

Note

These steps will take longer the first time the up command is run, but subsequent runs should be quicker.

Test the web app

Scan the console output for the Application started message, confirming that the up command has completed:

Service 'webfrontend' port 80 (TCP) is available at 'http://localhost:<port>'
Service 'webfrontend' port 'http' is available at http://webfrontend.1234567890abcdef1234.eus.azds.io/
Microsoft (R) Build Engine version 15.9.20+g88f5fadfbe for .NET Core
Copyright (C) Microsoft Corporation. All rights reserved.

  webfrontend -> /src/bin/Debug/netcoreapp2.2/webfrontend.dll
  webfrontend -> /src/bin/Debug/netcoreapp2.2/webfrontend.Views.dll

Build succeeded.
    0 Warning(s)
    0 Error(s)

Time Elapsed 00:00:00.94
[...]
webfrontend-5798f9dc44-99fsd: Now listening on: http://[::]:80
webfrontend-5798f9dc44-99fsd: Application started. Press Ctrl+C to shut down.

Identify the public URL for the service in the output from the up command. It ends in .azds.io. In the above example, the public URL is http://webfrontend.1234567890abcdef1234.eus.azds.io/.

To see your web app, open the public URL in a browser. Also, notice stdout and stderr output is streamed to the azds trace terminal window as you interact with your web app. You'll also see tracking information for HTTP requests as they go through the system. This makes it easier for you to track complex multi-service calls during development. The instrumentation added by Dev Spaces provides this request tracking.

azds trace terminal window

Note

In addition to the public URL, you can use the alternative http://localhost:<portnumber> URL that is displayed in the console output. If you use the localhost URL, it may seem like the container is running locally, but actually it is running in AKS. Azure Dev Spaces uses Kubernetes port-forward functionality to map the localhost port to the container running in AKS. This facilitates interacting with the service from your local machine.

Update a content file

Azure Dev Spaces isn't just about getting code running in Kubernetes - it's about enabling you to quickly and iteratively see your code changes take effect in a Kubernetes environment in the cloud.

  1. Locate the file ./Views/Home/Index.cshtml and make an edit to the HTML. For example, change line 73 that reads <h2>Application uses</h2> to something like:

    <h2>Hello k8s in Azure!</h2>
    
  2. Save the file. Moments later, in the Terminal window you'll see a message saying a file in the running container was updated.

  3. Go to your browser and refresh the page. You should see the web page display the updated HTML.

What happened? Edits to content files, like HTML and CSS, don't require recompilation in a .NET Core web app, so an active azds up command automatically syncs any modified content files into the running container in Azure, so you can see your content edits right away.

Update a code file

Updating code files requires a little more work, because a .NET Core app needs to rebuild and produce updated application binaries.

  1. In the terminal window, press Ctrl+C (to stop azds up).
  2. Open the code file named Controllers/HomeController.cs, and edit the message that the About page will display: ViewData["Message"] = "Your application description page.";
  3. Save the file.
  4. Run azds up in the terminal window.

This command rebuilds the container image and redeploys the Helm chart. To see your code changes take effect in the running application, go to the About menu in the web app.

But there is an even faster method for developing code, which you'll explore in the next section.

Debug a container in Kubernetes

In this section, you'll use VS Code to directly debug our container running in Azure. You'll also learn how to get a faster edit-run-test loop.

Note

If you get stuck at any time, see the Troubleshooting section, or post a comment on this page.

Initialize debug assets with the VS Code extension

You first need to configure your code project so VS Code will communicate with our dev space in Azure. The VS Code extension for Azure Dev Spaces provides a helper command to set up debug configuration.

Open the Command Palette (using the View | Command Palette menu), and use auto-complete to type and select this command: Azure Dev Spaces: Prepare configuration files for Azure Dev Spaces.

This adds debug configuration for Azure Dev Spaces under the .vscode folder. This command is not to be confused with the azds prep command, which configures the project for deployment.

Select the AZDS debug configuration

  1. To open the Debug view, click on the Debug icon in the Activity Bar on the side of VS Code.
  2. Select .NET Core Launch (AZDS) as the active debug configuration.

Note

If you don't see any Azure Dev Spaces commands in the Command Palette, ensure you have installed the VS Code extension for Azure Dev Spaces. Be sure the workspace you opened in VS Code is the folder that contains azds.yaml.

Debug the container in Kubernetes

Hit F5 to debug your code in Kubernetes.

As with the up command, code is synced to the dev space, and a container is built and deployed to Kubernetes. This time, of course, the debugger is attached to the remote container.

Tip

The VS Code status bar will turn orange, indicating that the debugger is attached. It will also display a clickable URL, which you can use to open your site.

Set a breakpoint in a server-side code file, for example within the About() function in the Controllers/HomeController.cs source file. Refreshing the browser page causes the breakpoint to hit.

You have full access to debug information just like you would if the code was executing locally, such as the call stack, local variables, exception information, etc.

Edit code and refresh

With the debugger active, make a code edit. For example, modify the About page's message in Controllers/HomeController.cs.

public IActionResult About()
{
    ViewData["Message"] = "My custom message in the About page.";
    return View();
}

Save the file, and in the Debug actions pane, click the Restart button.

Instead of rebuilding and redeploying a new container image each time code edits are made, which will often take considerable time, Azure Dev Spaces will incrementally recompile code within the existing container to provide a faster edit/debug loop.

Refresh the web app in the browser, and go to the About page. You should see your custom message appear in the UI.

Now you have a method for rapidly iterating on code and debugging directly in Kubernetes! Next, you'll see how you can create and call a second container.

Next steps