Visual Studio Code Docker



Get, create, and configure a container-based development environment with the Visual Studio Code Remote - Containers extension

Learning objectives

By the end of this module, you'll be able to:

  1. Docker is a very popular container platform that lets you easily package, deploy, and consume applications and services. Whether you are a seasoned Docker developer or just getting started, Visual Studio Code makes it easy to author Dockerfile and docker-compose.yml files in your workspace. Install the Docker extension.
  2. The docker build step here will be much faster than method 1. Additionally, you’ll be able to run unit tests and publish code coverage reports, or use custom plugins on the artifacts built by the CI. Docker Tools for Visual Studio; dockerize, dockerizing, dotnet,.NET.

The Docker extension provides a docker debug configuration provider that manages how VS Code will launch an application and/or attach a debugger to the application in a running Docker container. This provider is configured via entries within launch.json, with configuration being specific to each application platform supported by the provider.

  • Install the Visual Studio Code Remote - Containers extension
  • Load and connect to a project in a Docker container
  • Access ports in the container from your local machine
  • Customize settings while working with your container
  • Add software to the container environment

Prerequisites

  • A computer that's running one of the following:
    • Windows: Windows 10
    • Mac: macOS 10.9 or later
    • Linux: Ubuntu, Debian, Red Hat, Fedora, or SUSE
  • Basic knowledge of software development, such as what it means to run code and install a new language
  • Docker and basic Docker knowledge (familiarity with the concept of images, containers, and registries):
    • Windows: Docker Desktop 2.0+ on Windows 10 Pro/Enterprise. Windows 10 Home (2004+) requires Docker Desktop 2.3+ and the WSL 2 back end.
    • Mac: Docker Desktop 2.0+.
    • Linux: Docker CE/EE 18.06+ and Docker Compose 1.21+.
  • Git and basic knowledge of GitHub, such as what a repository is
  • Use the Remote - Containers extension in Visual Studio Codemin
  • Exercise - Add a dev container to an existing projectmin
  • Exercise - Customize project and editor settingsmin
  • Exercise - Add software to an existing containermin
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Docker Compose is a tool that was developed to help define and share multi-container applications. With Compose, you can create a YAML file to define the services and with a single command, can spin everything up or tear it all down.

Docker

The big advantage of using Compose is you can define your application stack in a file, keep it at the root of your project repo (it's now version controlled), and easily enable someone else to contribute to your project. Someone would only need to clone your repo and start the compose app. In fact, you might see quite a few projects on GitHub/GitLab doing exactly this now.

So, how do you get started?

Install Docker Compose

If you installed Docker Desktop for either Windows or Mac, you already have Docker Compose! Play-with-Docker instances already have Docker Compose installed as well. If you are on a Linux machine, you will need to install Docker Compose using the instructions here.

After installation, you should be able to run the following and see version information.

Create the compose file

  1. At the root of the app project, create a file named docker-compose.yml.

  2. In the compose file, we'll start off by defining the schema version. In most cases, it's best to use the latest supported version. You can look at the Compose file reference for the current schema versions and the compatibility matrix.

  3. Next, define the list of services (or containers) you want to run as part of your application.

And now, you'll start migrating a service at a time into the compose file.

Visual Studio Code Docker

Define the App Service

To remember, this was the command you used to define your app container (replace the characters with ` in Windows PowerShell).

  1. First, define the service entry and the image for the container. You can pick any name for the service. The name will automatically become a network alias, which will be useful when defining the MySQL service.

  2. Typically, you'll see the command close to the image definition, although there is no requirement on ordering. So, go ahead and move that into the file.

  3. Migrate the -p 3000:3000 part of the command by defining the ports for the service. You'll use the short syntax here, but there is also a more verbose long syntax available as well.

  4. Next, migrate both the working directory (-w /app) and the volume mapping (-v ${PWD}:/app) by using the working_dir and volumes definitions. Volumes also has a short and long syntax.

    One advantage of Docker Compose volume definitions is you can use relative paths from the current directory.

  5. Finally, migrate the environment variable definitions using the environment key.

Define the MySQL service

Now, it's time to define the MySQL service. The command that you used for that container was the following (replace the characters with ` in Windows PowerShell):

  1. First, define the new service and name it mysql so it automatically gets the network alias. Specify the image to use as well.

  2. Next, define the volume mapping. When you ran the container with docker run, the named volume was created automatically. However, that doesn't happen when running with Compose. You need to define the volume in the top-level volumes: section and then specify the mountpoint in the service config. By simply providing only the volume name, the default options are used. There are many more options available though.

  3. Finally, you only need to specify the environment variables.

At this point, the complete docker-compose.yml should look like this:

Run the application stack

Now that you have the docker-compose.yml file, you can start it up!

  1. First, make sure no other copies of the app and database are running (docker ps and docker rm -f <ids>).

  2. Start up the application stack using the docker-compose up command. Add the -d flag to run everything in the background. Alternatively, you can right-click on your Compose file and select the Compose Up option for the VS Code side bar.

    When you run this, you should see output like this:

    You'll notice that the volume was created as well as a network! By default, Docker Compose automatically creates a network specifically for the application stack (which is why you didn't define one in the compose file).

  3. Look at the logs using the docker-compose logs -f command. You'll see the logs from each of the services interleaved into a single stream. This is incredibly useful when you want to watch for timing-related issues. The -f flag 'follows' the log, so will give you live output as it's generated.

    If you don't already, you'll see output that looks like this:

    The service name is displayed at the beginning of the line (often colored) to help distinguish messages. If you want to view the logs for a specific service, you can add the service name to the end of the logs command (for example, docker-compose logs -f app).

    Tip

    Waiting for the DB before starting the appWhen the app is starting up, it actually sits and waits for MySQL to be up and ready before trying to connect to it.Docker doesn't have any built-in support to wait for another container to be fully up, running, and ready before starting another container. For Node-based projects, you can use the wait-port dependency. Similar projects exist for other languages/frameworks.

  4. At this point, you should be able to open your app and see it running. And hey! You're down to a single command!

See the app stack in the Docker extension

If you look at the Docker extension, you can change the grouping options using the 'cog' and 'group by'. In this instance, you want to see containers grouped by Compose Project name:

If you twirl down the network, you will see the two containers you defined in the compose file.

Tear it all down

When you're ready to tear it all down, simply run docker-compose down, or right-click on the application in the containers list in the VS Code Docker extension and select Compose Down. The containers will stop and the network will be removed.

Warning

Visual Studio Code Docker Build

Removing VolumesBy default, named volumes in your compose file are NOT removed when running docker-compose down. If you want to remove the volumes, you will need to add the --volumes flag.

Once torn down, you can switch to another project, run docker-compose up and be ready to contribute to that project! It really doesn't get much simpler than that!

Recap

In this section, you learned about Docker Compose and how it helps dramatically simplify the defining and sharing of multi-service applications. You created a Compose file by translating the commands you were using into the appropriate compose format.

At this point, you're starting to wrap up the tutorial. However, there are a few best practices about image building to cover, as there is a big issue with the Dockerfile you've been using. So, let's take a look!

Visual Studio Code Docker Environment

Next steps

Visual Studio Code Docker Compose

Continue with the tutorial!