Build Java development environment with WSL2 Docker VS Code

Creating a development environment with WSL2, Docker and VS Code was a hot topic, so I tried it. Although I made it, the operation of the development environment was too heavy and I got stuck. The reason was that the development source was in the Windows folder instead of the lightweight Linux folder. I will leave the procedure as a commandment to myself.

Installation of WSL2

Enable the Windows subsystem for Linux

Open PowerShell as an administrator and do the following:

dism.exe /online /enable-feature /featurename:Microsoft-Windows-Subsystem-Linux /all /norestart

Enable virtual machine functionality

Open PowerShell as an administrator and do the following:

dism.exe /online /enable-feature /featurename:VirtualMachinePlatform /all /norestart

Reboot the machine.

Download the Linux kernel update package

Download and install the latest package. WSL2 Linux Kernel Update Package for x64 Machines (https://wslstorestorage.blob.core.windows.net/wslblob/wsl_update_x64.msi)

Set WSL 2 as the default version

Open PowerShell and run the following command to set WSL 2 as the default version when installing a new Linux distribution.

wsl --set-default-version 2

Install the selected Linux distribution

Open the Microsoft Store (https://aka.ms/wslstore), search for and select the desired Linux distribution.
On the distribution page, select Get. Get Ubuntu 20.04 LTS here.
Start Ubuntu 20.04LTS and enter your user name and password.
Update Ubuntu with the command sudo apt-get update.

Check the WSL folder

You can access the WSL Linux file system from Windows by entering the following path in Explorer.

\\wsl$

For Ubuntu 20.04LTS:

\\wsl$\Ubuntu-20.04

When developing using WSL + Docker, place the source etc. under this.

Also, if you browse the Windows folder from WSL, you can see from the WSL terminal. It will be as follows.

/mnt/c/

Please be aware that if you place the source under this, the file I/O will be abnormally slow because the reference will be made from the Linux system to the Windows system.

Limit WSL resources

WSL seems to reserve 80% of the host machine's physical memory by default, Change the settings as it may cause the host to run out of memory. Describe the settings in the following file (or create a new one if there is none). %USERPROFILE%\.wslconfig

The description is as follows.

[wsl2]
memory=4GB
swap=0
processors=2

See WSL Command and Startup Configuration (https://docs.microsoft.com/ja-jp/windows/wsl/wsl-config#configuration-options) for more information.

Restart WSL for the settings to take effect.

Execute the following command from PowerShell and restart the WSL terminal to restart it.

wsl --shutdown

To check the WSL that is running, execute the following command in PowerShell.

wsl -l -v

Docker installation / configuration

Installation

Install Docker Desktop Check Enable WSL 2 Windows Features during installation

Configuration

Launch Docker Desktop, right-click the Docker icon on the taskbar and launch setteings

--General has a check mark on Use the WSL 2 based engine --In Resources, Enable integration with my default WSL distro is checked.

You can use Docker Desktop from Distro, which is specified in the list displayed by the wsl -l command in PowerShell.

VS Code settings

Setting environment variables

If you set the VScode bin folder in the Windows environment variable PATH as shown below You will be able to start VS Code with a command from WSL. C:\app\VSCode\bin

Extension installation

Install Remote Development.

Remote Development includes multiple extensions, This time we will use Remote --Container in particular. Other extensions such as the following are also installed.

Remote - WSL
Remote - SSH

Launch VS Code

--Start Windows Terminal or Ubuntu Terminal --Run the command cd ~ to move to your home folder --Check the home folder path with the command pwd On WSL it will be / home/username. On Windows it will be \\ wsl $ \ Ubuntu-20.04 \ home \ username. --Create and move any folder

mkdir dev_root
cd dev_root

--Launch VsCode

code .

Creating a Remote container

Press ctrl + shift + p and Enter remote-containers: Open Folder in Container

The following prompts will be displayed, so make each selection.

Select a folder
Select Docker image → select java
Select Java version → Select 11
Select build tool → select maven gradle node as you like

Creating a Java project

From VsCode terminal Create a project template with spring boot initial izr

curl https://start.spring.io/starter.zip \
       -d dependencies=web \
       -d javaVersion=11 \
       -o demo.zip

Unzip the project template

unzip demo.zip

Edit DemoApplication.java as follows

package com.example.demo;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;

@RestController
@SpringBootApplication
public class DemoApplication {

	public static void main(String[] args) {
		SpringApplication.run(DemoApplication.class, args);
	}

	@GetMapping("/")
	public String index(){
		return "hello World";
	}

}

Press the F5 key to debug and access http://localhost:8080/

Supplement about Remote-Container

When using Remote-Container The .devcontainer folder is created, and the following two files are created there.

devcontainer.json Here you can specify the Docker file or Docker Compose file to build, You can describe the VsCode settings of the container (java.home, etc.) and the extensions you want to install (spring-boot-extention-pack, etc.).
Dockerfile It will be a Docker file for building the container. This time I used the Docker image provided by the extension (MS), You can change it to your favorite Docker image uploaded to Docker Hub etc.

This article was written with reference to the following information.

-Installation Guide for Windows Subsystem for Linux for Windows 10 -Learn more about memory management in Windows Subsystem for Linux 2