11/24/2021»»Wednesday

Install Docker In A Container

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This step-by-step guide will help you get started developing with remote containers by setting up Docker Desktop for Windows with WSL 2 (Windows Subsystem for Linux, version 2).

Docker enables developers to deploy applications inside containers for testing code in an environment identical to production. PyCharm provides Docker support using the Docker plugin. The plugin is bundled and enabled by default in PyCharm Professional Edition. For PyCharm Community Edition, you need to install the Docker plugin as described in. I want to establish docker containers in the host docker container. I had a similar problem trying to install Docker inside a Bamboo Server image.

Docker Desktop for Windows provides a development environment for building, shipping, and running dockerized apps. By enabling the WSL 2 based engine, you can run both Linux and Windows containers in Docker Desktop on the same machine. (Docker Desktop is free for personal use and small businesses, for info on Pro, Team, or Business pricing, see the Docker site FAQs).

Overview of Docker containers

Docker is a tool used to create, deploy, and run applications using containers. Containers enable developers to package an app with all of the parts it needs (libraries, frameworks, dependencies, etc) and ship it all out as one package. Using a container ensures that the app will run the same regardless of any customized settings or previously installed libraries on the computer running it that could differ from the machine that was used to write and test the app's code. This permits developers to focus on writing code without worrying about the system that code will be run on.

Docker containers are similar to virtual machines, but don't create an entire virtual operating system. Instead, Docker enables the app to use the same Linux kernel as the system that it's running on. This allows the app package to only require parts not already on the host computer, reducing the package size and improving performance.

Continuous availability, using Docker containers with tools like Kubernetes, is another reason for the popularity of containers. This enables multiple versions of your app container to be created at different times. Rather than needing to take down an entire system for updates or maintenance, each container (and it's specific microservices) can be replaced on the fly. You can prepare a new container with all of your updates, set up the container for production, and just point to the new container once it's ready. You can also archive different versions of your app using containers and keep them running as a safety fallback if needed.

To learn more, checkout the Introduction to Docker containers on Microsoft Learn.

Prerequisites

  • Ensure your machine is running Windows 10, updated to version 2004, Build 18362 or higher.
  • Install WSL and set up a user name and password for your Linux distribution running in WSL 2.
  • Install Visual Studio Code(optional). This will provide the best experience, including the ability to code and debug inside a remote Docker container and connected to your Linux distribution.
  • Install Windows Terminal(optional). This will provide the best experience, including the ability to customize and open multiple terminals in the same interface (including Ubuntu, Debian, PowerShell, Azure CLI, or whatever you prefer to use).
  • Sign up for a Docker ID at Docker Hub(optional).

Note

WSL can run distributions in both WSL version 1 or WSL 2 mode. You can check this by opening PowerShell and entering: wsl -l -v. Ensure that the your distribution is set to use WSL 2 by entering: wsl --set-version <distro> 2. Replace <distro> with the distro name (e.g. Ubuntu 18.04).

In WSL version 1, due to fundamental differences between Windows and Linux, the Docker Engine couldn't run directly inside WSL, so the Docker team developed an alternative solution using Hyper-V VMs and LinuxKit. However, since WSL 2 now runs on a Linux kernel with full system call capacity, Docker can fully run in WSL 2. This means that Linux containers can run natively without emulation, resulting in better performance and interoperability between your Windows and Linux tools.

Install Docker Desktop

With the WSL 2 backend supported in Docker Desktop for Windows, you can work in a Linux-based development environment and build Linux-based containers, while using Visual Studio Code for code editing and debugging, and running your container in the Microsoft Edge browser on Windows.

To install Docker (after already installing WSL):

  1. Download Docker Desktop and follow the installation instructions.

  2. Once installed, start Docker Desktop from the Windows Start menu, then select the Docker icon from the hidden icons menu of your taskbar. Right-click the icon to display the Docker commands menu and select 'Settings'.

  3. Ensure that 'Use the WSL 2 based engine' is checked in Settings > General.

  4. Select from your installed WSL 2 distributions which you want to enable Docker integration on by going to: Settings > Resources > WSL Integration.

  5. To confirm that Docker has been installed, open a WSL distribution (e.g. Ubuntu) and display the version and build number by entering: docker --version

  6. Test that your installation works correctly by running a simple built-in Docker image using: docker run hello-world

Install Docker In A Container

Tip

Here are a few helpful Docker commands to know:

  • List the commands available in the Docker CLI by entering: docker
  • List information for a specific command with: docker <COMMAND> --help
  • List the docker images on your machine (which is just the hello-world image at this point), with: docker image ls --all
  • List the containers on your machine, with: docker container ls --all or docker ps -a (without the -a show all flag, only running containers will be displayed)
  • List system-wide information regarding the Docker installation, including statistics and resources (CPU & memory) available to you in the WSL 2 context, with: docker info

Develop in remote containers using VS Code

Install Docker In A Container

To get started developing apps using Docker with WSL 2, we recommend using VS Code, along with the Remote-WSL extension and Docker extension.

  • Install the VS Code Remote-WSL extension. This extension enables you to open your Linux project running on WSL in VS Code (no need to worry about pathing issues, binary compatibility, or other cross-OS challenges).

  • Install the VS code Remote-Containers extension. This extension enables you to open your project folder or repo inside of a container, taking advantage of Visual Studio Code's full feature set to do your development work within the container.

  • Install the VS Code Docker extension. This extension adds the functionality to build, manage, and deploy containerized applications from inside VS Code. (You need the Remote-Container extension to actually use the container as your dev environment.)

Let's use Docker to create a development container for an existing app project.

  1. For this example, I'll use the source code from my Hello World tutorial for Django in the Python development environment set up docs. You can skip this step if you prefer to use your own project source code. To download my HelloWorld-Django web app from GitHub, open a WSL terminal (Ubuntu for example) and enter: git clone https://github.com/mattwojo/helloworld-django.git

    Note

    Always store your code in the same file system that you're using tools in. This will result in faster file access performance. In this example, we are using a Linux distro (Ubuntu) and want to store our project files on the WSL file system wsl. Storing project files on the Windows file system would significantly slow things down when using Linux tools in WSL to access those files.

  2. From your WSL terminal, change directories to the source code folder for this project:

  3. Open the project in VS Code running on the local Remote-WSL extension server by entering:

    Confirm that you are connected to your WSL Linux distro by checking the green remote indicator in the bottom-left corner of your VS Code instance.

  4. From the VS Code command pallette (Ctrl + Shift + P), enter: Remote-Containers: Open Folder in Container... If this command doesn't display as you begin to type it, check to ensure that you've installed the Remote Container extension linked above.

  5. Select the project folder that you wish to containerize. In my case, this is wslUbuntu-20.04homemattwojoreposhelloworld-django

  6. A list of container definitions will appear, since there is no DevContainer configuration in the project folder (repo) yet. The list of container configuration definitions that appears is filtered based on your project type. For my Django project, I'll select Python 3.

  7. A new instance of VS Code will open, begin building our new image, and once the build completed, will start our container. You will see that a new .devcontainer folder has appeared with container configuration information inside a Dockerfile and devcontainer.json file.

  8. To confirm that your project is still connected to both WSL and within a container, open the VS Code integrated terminal (Ctrl + Shift + ~). Check the operating system by entering: uname and the Python version with: python3 --version. You can see that the uname came back as 'Linux', so you are still connected to the WSL 2 engine, and Python version number will be based on the container config that may differ from the Python version installed on your WSL distribution.

  9. To run and debug your app inside of the container using Visual Studio Code, first open the Run menu (Ctrl+Shift+D or select the tab on the far left menu bar). Then select Run and Debug to select a debug configuration and choose the configuration that best suites your project (in my example, this will be 'Django'). This will create a launch.json file in the .vscode folder of your project with instructions on how to run your app.

  10. From inside VS Code, select Run > Start debugging (or just press the F5 key). This will open a terminal inside VS Code and you should see a result saying something like: 'Starting development server at http://127.0.0.1:8000/ Quit the server with CONTROL-C.' Hold down the Control key and select the address displayed to open your app in your default web browser and see your project running inside of its container.

Install Docker In A Container

You have now successfully configured a remote development container using Docker Desktop, powered by the WSL 2 backend, that you can code in, build, run, deploy, or debug using VS Code!

Troubleshooting

WSL docker context deprecated

If you were using an early Tech Preview of Docker for WSL, you may have a Docker context called 'wsl' that is now deprecated and no longer used. You can check with the command: docker context ls. You can remove this 'wsl' context to avoid errors with the command: docker context rm wsl as you want to use the default context for both Windows and WSL2.

Possible errors you might encounter with this deprecated wsl context include: docker wsl open //./pipe/docker_wsl: The system cannot find the file specified. or error during connect: Get http://%2F%2F.%2Fpipe%2Fdocker_wsl/v1.40/images/json?all=1: open //./pipe/docker_wsl: The system cannot find the file specified.

For more on this issue, see How to set up Docker within Windows System for Linux (WSL2) on Windows 10.

Trouble finding docker image storage folder

Docker creates two distro folders to store data:

Install Ssh In A Docker Container

  • wsl$docker-desktop
  • wsl$docker-desktop-data

You can find these folders by opening your WSL Linux distribution and entering: explorer.exe . to view the folder in Windows File Explorer. Enter: wsl<distro name>mntwsl replacing <distro name> with the name of your distribution (ie. Ubuntu-20.04) to see these folders.

Find more on locating docker storage locations in WSL, see this issue from the WSL repo or this StackOverlow post.

For more help with general troubleshooting issues in WSL, see the Troubleshooting doc.

Additional resources

Initially, the inception of Docker containerization started out with Linux as its base platform. However, over the years, Docker and Microsoft have continuously grown their partnership, creating a conveniently consistent interface for building, shipping, and running applications without the usual dependence hurdles associated with virtual machines.

Though a huge number of enterprises are already using Docker on Windows platforms, there has been a number of subtle functionality disparities between Windows and Linux containers. However, Windows Server 2019 (1809 build) has successfully addressed most of the inconsistencies between Docker containers in Linux and Windows environments.

Requirements for Installation of Docker on Windows

Docker containers are powered by a Docker engine. Though initially designed for Linux, extensive work has been done to allow Docker containers to run on Windows and macOS environments.

To run Docker containers on a Windows platform, one prerequisite is the installation of a Windows server. You can do this in a physical server machine, on a cloud environment running in Azure, or an on-premise virtual machine.

Install the Hyper-V feature on your Windows server 2019

There are two distinct modes to run Decker containers on Windows platforms: Process isolation and Hyper-V isolation. With the Process isolation mode, the Docker containers share the OS kernel with the host platform, hence they are lightweight and identical to Linux system Docker containers.

On the other hand, the running of Docker containers in the Hyper-V mode is confined to a special nominal virtual machine. This enables improved compatibility and secure kernel-level. To run Docker containers in this mode, you must first enable Hyper-V in the host operating system.

The default operation mode for Docker installation on a Windows server is the operation mode (enabling Hyper-V is optional). However, it’s a prerequisite to enable the Hyper-V isolation mode if you need to run Linux containers on a Windows Server interface.

Docker

The OS build is another crucial determinant on the need for Hyper-V mode as Windows containers should be of the same build version as the container host OS’s version. Still, Windows container images with a lower build version than the container host OS can run with Hyper-V isolation.

To install Hyper-V on Windows Server 2019, run the PowerShell as Administrator and run the commands below:

Enable-WindowsOptionalFeature –Online -FeatureName Microsoft-Hyper-V –All -NoRestart

Install-WindowsFeature RSAT-Hyper-V-Tools -IncludeAllSubFeature

Next, restart your Windows Server VM.

Install Docker Inside A Container

Prerequisites for the container host

You must enable virtualization in the hosting Windows server platform to utilize Hyper-V isolation in your containers: enable hardware virtualization for a container host running on hardware and nested virtualization in the base interface for a container host running on a cloud space or Hyper-V.

Running Docker Containers on Windows Server 2019

Before running multiple isolated applications using Windows Containers, you need to activate (enable) the containers feature and install Docker on your Windows Server 2019. Here’s the process:

  1. Enable the containers feature in Windows Server 2019.

Run PowerShell as an Administrator and run this command:

Install-Module -Name DockerMsftProvider -Repository PSGallery -Force

Home

This command will install the Docker-Microsoft Package Management Provider from the PowerShell Gallery.

When prompted to install and import NuGet provider, type Y and hit ENTER

  1. Install Docker on your Windows Server 2019

After installing the Containers feature on Windows Server 2019, it’s time to install the latest versions of Docker Engine and Docker Client. Run this command in your PowerShell session:

Install-Package -Name docker -ProviderName DockerMsftProvider

Accept the installation by selecting “Yes”, “Y” or “A” to Agree to all the installation requests.

After the completion of this installation, reboot your computer.

Restart-Computer –Force

You can check your installed Docker version via the PowerShell command:

Get-Package -Name Docker -ProviderName DockerMsftProvider


You can also confirm the installed Docker version using the docker –version command:

docker –version

You can opt to upgrade anytime by running the commands below on PowerShell:

Install-Package -Name Docker -ProviderName DockerMsftProvider -Update -Force

Then start the docker service.

Start-Service Docker

  1. Launch (Run) Docker Containers on Windows Server 2019

Run the following commands on PowerShell:

Start-Service Docker

After starting the Docker Engine service, proceed to download the pre-created .NET sample image on the Docker Hub registry:

docker pull microsoft/dotnet-samples:dotnetapp-nanoserver-1809

After the download, you can deploy a simple Docker container that runs the .Net ‘Hello World’ application:

docker run microsoft/dotnet-samples:dotnetapp-nanoserver-1809

After running the command, an ASCII image will be printed to the shell accompanied by the “Hello” message.

Running Linux Containers on your Window Server 2019

By default, Docker on Windows only runs Windows containers. To launch Linux containers on Windows Server, use the Docker Enterprise Edition Preview that comes with a full LinuxKit system to run Docker Linux containers.

  1. First, uninstall the already installed Docker CE.

Uninstall-Package -Name docker -ProviderName DockerMSFTProvider

  1. Enable Nested Virtualization in case you’re running Docker Containers on a Linux Virtual Machine running on Hyper-V.

Get-VM WinContainerHost Set-VMProcessor -ExposeVirtualizationExtensions $true

NOTE:WinContainerHost is the name of your virtual machine

  1. Install the Module Docker Provider

Install-Module DockerProvider

Install-Package Docker -ProviderName DockerProvider -RequiredVersion preview

A restart will be required after this operation

  1. Enable LinuxKit system to run Linux containers

[Environment]::SetEnvironmentVariable(“LCOW_SUPPORTED”, “1”, “Machine”)

  1. Restart the Docker Service after the change above and restart the Service Docker

Restart-Service docker

Container

Install Docker In A Containers

To switch back to running Windows containers, execute the following command in PowerShell:

Install Docker Compose In A Container

[Environment]::SetEnvironmentVariable(“LCOW_SUPPORTED”, “$null”, “Machine”)

You have finally installed and configured Docker your Windows Server machine to run both Linux and Windows containers. We hope this guide was insightful.

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