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Setting up your Java project for Codespaces

Get started with your Java project in Codespaces by creating a custom dev container.

Codespaces está disponible para las organizaciones que utilicen GitHub Team o Nube de GitHub Enterprise. Para obtener más información, consulta la sección "Productos de GitHub".

Introduction

This guide shows you how to set up your Java project in Codespaces. It will take you through an example of opening your project in a codespace, and adding and modifying a dev container configuration from a template.

Prerequisites

  • You should have an existing Java project in a repository on GitHub.com. If you don't have a project, you can try this tutorial with the following example: https://github.com/microsoft/vscode-remote-try-java
  • You must have Codespaces enabled for your organization.

Step 1: Open your project in a codespace

  1. Under the repository name, use the Code drop-down menu, and in the Codespaces tab, click Create codespace on main.

    New codespace button

    If you don’t see this option, Codespaces isn't available for your project. See Access to Codespaces for more information.

When you create a codespace, your project is created on a remote VM that is dedicated to you. By default, the container for your codespace has many languages and runtimes including Java, nvm, npm, and Yarn. It also includes a common set of tools like git, wget, rsync, openssh, and nano.

Puedes personalizar tu codespace si ajustas la cantidad de vCPU y RAM, agregando dotfiles para personalizar tu ambiente o modificando las herramientas y scripts instalados.

Codespaces uses a file called devcontainer.json to configure the development container that you use when you work in a codespace. Each repository can contain one or more devcontainer.json files, to give you exactly the development environment you need to work on your code in a codespace.

On launch, Codespaces uses a devcontainer.json file, and any dependent files that make up the dev container configuration, to install tools and runtimes, and perform other setup tasks that the project requires. Para obtener más información, consulta la sección "Introducción a los contenedores dev".

Step 2: Add a dev container configuration to your repository from a template

The default development container, or "dev container," for Acerca de GitHub Codespaces comes with the latest Java version, package managers (Maven, Gradle), and other common tools preinstalled. However, we recommend that you configure your own dev container to include all of the tools and scripts that your project needs. This will ensure a fully reproducible environment for all Acerca de GitHub Codespaces users in your repository.

To set up your repository to use a custom dev container, you will need to create one or more devcontainer.json files. You can add these either from a template, in Visual Studio Code, or you can write your own. For more information on dev container configurations, see "Introduction to dev containers".

  1. Accede a la Paleta de comandos de Visual Studio Code (Shift + Command + P / Ctrl + Shift + P) y comienza a teclear "dev container". Selecciona Codespaces: Agregar archivos de configuración del contenedor de desarrollo....

    "Codespaces: Agregar archivos de configuración de contenedor de desarrollo..." en la Paleta de comandos de Visual Studio Code

  2. For this example, click Java. In practice, you could select any container that’s specific to Java or a combination of tools such as Java and Azure Functions. Select Java option from the list

  3. Click the recommended version of Java. Java version selection

  4. Accede a la Paleta de comandos de Visual Studio Code (Shift + Command + P/ Ctrl + Shift + P) y luego comienza a escribir "rebuild". Selecciona Codespaces: Reconstruir contenedor.

    Opción de recompilar contenedor

Anatomy of your dev container

Adding the Java dev container template adds a .devcontainer directory to the root of your project's repository with the following files:

  • devcontainer.json
  • Dockerfile

The newly added devcontainer.json file defines a few properties that are described after the sample.

devcontainer.json

// For format details, see https://aka.ms/vscode-remote/devcontainer.json or this file's README at:
// https://github.com/microsoft/vscode-dev-containers/tree/v0.159.0/containers/java
{
	"name": "Java",
	"build": {
		"dockerfile": "Dockerfile",
		"args": {
			// Update the VARIANT arg to pick a Java version: 11, 14
			"VARIANT": "11",
			// Options
			"INSTALL_MAVEN": "true",
			"INSTALL_GRADLE": "false",
			"INSTALL_NODE": "false",
			"NODE_VERSION": "lts/*"
		}
	},

	// Set *default* container specific settings.json values on container create.
	"settings": {
		"terminal.integrated.shell.linux": "/bin/bash",
		"java.home": "/docker-java-home",
		"maven.executable.path": "/usr/local/sdkman/candidates/maven/current/bin/mvn"
	},

	// Add the IDs of extensions you want installed when the container is created.
	"extensions": [
		"vscjava.vscode-java-pack"
	],

	// Use 'forwardPorts' to make a list of ports inside the container available locally.
	// "forwardPorts": [],

	// Use 'postCreateCommand' to run commands after the container is created.
	// "postCreateCommand": "java -version",

	// Uncomment to connect as a non-root user. See https://aka.ms/vscode-remote/containers/non-root.
	"remoteUser": "vscode"
}
  • name - You can name your dev container anything, this is just the default.
  • build - The build properties.
    • dockerfile - In the build object, dockerfile contains the path to the Dockerfile that was also added from the template.
    • args
      • variant: This file only contains one build argument, which is the Java version that is passed into the Dockerfile.
  • settings - These are Visual Studio Code settings that you can set.
    • terminal.integrated.shell.linux - While bash is the default here, you could use other terminal shells by modifying this.
  • extensions - These are extensions included by default.
    • vscjava.vscode-java-pack - The Java Extension Pack provides popular extensions for Java development to get you started.
  • forwardPorts - Any ports listed here will be forwarded automatically. For more information, see "Forwarding ports in your codespace."
  • postCreateCommand - Use this to run commands that aren't defined in the Dockerfile, after your codespace is created.
  • remoteUser - By default, you’re running as the vscode user, but you can optionally set this to root.

Dockerfile

# See here for image contents: https://github.com/microsoft/vscode-dev-containers/tree/v0.159.0/containers/java/.devcontainer/base.Dockerfile
ARG VARIANT="14"
FROM mcr.microsoft.com/vscode/devcontainers/java:0-${VARIANT}

# [Optional] Install Maven or Gradle
ARG INSTALL_MAVEN="false"
ARG MAVEN_VERSION=3.6.3
ARG INSTALL_GRADLE="false"
ARG GRADLE_VERSION=5.4.1
RUN if [ "${INSTALL_MAVEN}" = "true" ]; then su vscode -c "source /usr/local/sdkman/bin/sdkman-init.sh && sdk install maven \"${MAVEN_VERSION}\""; fi \
    && if [ "${INSTALL_GRADLE}" = "true" ]; then su vscode -c "source /usr/local/sdkman/bin/sdkman-init.sh && sdk install gradle \"${GRADLE_VERSION}\""; fi

# [Optional] Install a version of Node.js using nvm for front end dev
ARG INSTALL_NODE="true"
ARG NODE_VERSION="lts/*"
RUN if [ "${INSTALL_NODE}" = "true" ]; then su vscode -c "source /usr/local/share/nvm/nvm.sh && nvm install ${NODE_VERSION} 2>&1"; fi

# [Optional] Uncomment this section to install additional OS packages.
# RUN apt-get update && export DEBIAN_FRONTEND=noninteractive \
#     && apt-get -y install --no-install-recommends <your-package-list-here>

# [Optional] Uncomment this line to install global node packages.
# RUN su vscode -c "source /usr/local/share/nvm/nvm.sh && npm install -g <your-package-here>" 2>&1

You can use the Dockerfile to add additional container layers to specify OS packages, Java versions, or global packages we want included in our container.

Step 3: Modify your devcontainer.json file

With your dev container configuration added and a basic understanding of what everything does, you can now make changes to customize your environment further. In this example, you'll add properties to install extensions and your project dependencies when your codespace launches.

  1. In the Explorer, select the devcontainer.json file from the tree to open it. You might have to expand the .devcontainer folder to see it.

    devcontainer.json file in the Explorer

  2. Add the following lines to your devcontainer.json file after extensions.

    JSON
    "postCreateCommand": "npm install",
    "forwardPorts": [4000],

    For information about the settings and properties that you can set in a devcontainer.json file, see "devcontainer.json reference" in the VS Code documentation.

  3. Accede a la Paleta de comandos de Visual Studio Code (Shift + Command + P/ Ctrl + Shift + P) y luego comienza a escribir "rebuild". Selecciona Codespaces: Reconstruir contenedor.

    Opción de recompilar contenedor

    Reconstruir dentro de tu codespace garantiza que tus cambios funcionan como se espera antes de que confirmes los cambios en el repositorio. Si algo resulta en un fallo, se te colocará en un codespace con un contenedor de recuperación desde el cual puedes reconstruir para seguir ajustando tu contenedor.

Step 4: Run your application

In the previous section, you used the postCreateCommand to install a set of packages via npm. You can now use this to run our application with npm.

  1. Run your application by pressing F5.

  2. When your project starts, you should see a toast in the bottom right corner with a prompt to connect to the port your project uses.

    Port forwarding toast

Step 5: Commit your changes

Una vez que hayas hecho cambios a tu codespace, ya sea de código nuevo o de cambios de configuración, necesitarás confirmar tus cambios. El confirmar los cambios en tu repositorio garantiza que cualquiera que cree un codespace desde este repositorio tendrá la misma configuración. Esto también significa que cualquier personalización que hagas, tal como agregar extensiones de VS Code, aparecerá para todos los usuarios.

Para obtener más información, consulta la sección "Utilizar el control de código fuente en tu codespace"

Next steps

You should now be ready start developing your Java project in Codespaces. Here are some additional resources for more advanced scenarios.