[DOCKER] Let me do VS Code Remote Development + Java development in Proxy environment

Hello **.

Suddenly, you want to develop Java in VS Code and the execution environment in a container. But there are some who get in the way. Yes, it's a Proxy.

In the case of an in-house proxy, I think that the situation is different for each company, but as a successful example, if it helps you a little ...

: muscle: Motivation

--I want to do Remote Development of VS Code using Docker under Proxy environment! --Voices require proxy settings ...: japanese_ogre: ――If you have any hints for those who are worried about proxies!

: computer: Operation check environment (host)

: hand_splayed: Premise

: file_folder: Files to prepare


Click here for Dockerfile in the Remote Development environment.


FROM adoptopenjdk/openjdk11:jdk-11.0.7_10-centos

# This Dockerfile adds a non-root user with sudo access. Use the "remoteUser"
# property in devcontainer.json to use it. On Linux, the container user's GID/UIDs
# will be updated to match your local UID/GID (when using the dockerFile property).
# See https://aka.ms/vscode-remote/containers/non-root-user for details.

ARG MAVEN_SHA=b4880fb7a3d81edd190a029440cdf17f308621af68475a4fe976296e71ff4a4b546dd6d8a58aaafba334d309cc11e638c52808a4b0e818fc0fd544226d952544

#Proxy settings
# devcontainer.Specify with json
# see https://code.visualstudio.com/docs/remote/containers-advanced#_option-2-use-an-env-file
ENV http_proxy=${PROXY}
ENV https_proxy=${PROXY}

RUN echo "building..." \
    # Create a non-root user to use if preferred
    # see https://aka.ms/vscode-remote/containers/non-root-user.
    && groupadd --gid ${USER_GID} ${USERNAME} \
    && useradd -s /bin/bash --uid ${USER_UID} --gid ${USER_GID} -m ${USERNAME} \
    # Install Maven
    && mkdir -p /usr/share/maven /usr/share/maven/ref \
    && curl -fsSL -o /tmp/apache-maven.tar.gz https://archive.apache.org/dist/maven/maven-3/${MAVEN_VERSION}/binaries/apache-maven-${MAVEN_VERSION}-bin.tar.gz \
    && echo "${MAVEN_SHA} /tmp/apache-maven.tar.gz" | sha512sum -c - \
    && tar -xzf /tmp/apache-maven.tar.gz -C /usr/share/maven --strip-components=1 \
    && rm -f /tmp/apache-maven.tar.gz \
    && ln -s /usr/share/maven/bin/mvn /usr/bin/mvn \
    # Maven User Settings
    # /home/vscode/.m2/And change ownership to vscode user
    && mkdir /home/${USERNAME}/.m2 \
    && chown -R ${USERNAME}:${USERNAME} /home/${USERNAME}/.m2

#Maven path setting
ENV MAVEN_HOME /usr/share/maven

I'm using Maven for development, so I have Maven installed. Also, since the production execution environment is CentOS 7 series, the Remote Development environment also uses CentOS 7 series + Java as the base image.

There is $ {PROXY}, but this is passed from devcontainer.json described later at the time of image build. I thought it would be a bit of an embedding in the image at build time, but since I have no plans to share the image directly in each person's development environment, I decided that there would be no problem in this state.


Next is the Remote Development environment configuration file devcontainer.json.


  "name": "Sample Project",
  "dockerFile": "Dockerfile",

  //Settings at the time of docker build (image creation)
  // see - https://github.com/microsoft/vscode-remote-release/issues/46
  "build": {
    "args": {
      // TODO:Described according to the environment
      "PROXY": "http://USER:PASS@HOST:PORT"

  //VS Code default settings when creating a container (note that the workspace settings win)
  "settings": { 
    "terminal.integrated.shell.linux": "/bin/bash",
    "java.home": "/opt/java/openjdk",
    // Language Server
    // see - https://github.com/redhat-developer/vscode-java/wiki/Using-a-Proxy
    // TODO:Described according to the environment
    "java.jdt.ls.vmargs": "-Dhttp.proxyHost=HOST -Dhttp.proxyPort=PORT -Dhttp.proxyUser=USER -Dhttp.proxyPassword=PASS -Dhttps.proxyHost=HOST -Dhttps.proxyPort=PORT -Dhttps.proxyUser=USER -Dhttps.proxyPassword=PASS",
    // see - https://github.com/redhat-developer/vscode-java/issues/399#issuecomment-355113311
    "java.import.gradle.enabled": false

  //VS Code extension installed when container is created (specified by ID)
  "extensions": [
    // Java
    "vscjava.vscode-java-pack",  // Java Extension Pack

  //Command executed after container creation
  "postCreateCommand": "./.devcontainer/postCreateCommand.sh",

  // Use 'forwardPorts' to make a list of ports inside the container available locally.
  "forwardPorts": [
    8090 // app

  //Docker container login user
  "remoteUser": "vscode",

The point is java.jdt.ls.vmargs in settings. As you can see on the page below, it seems that you need to set PROXY for Java Language Server.

Using a Proxy - redhat-developer/vscode-java - GitHub

Maven config file

Maven configures Proxy settings in Maven.

I put these files in the .devcontainer folder. Copy it to the .m2 folder (/home/vscode/.m2) directly under the vscode user home with the shell described below.


    <!-- TODO:Described according to the environment-->


<?xml version="1.0" encoding="UTF-8"?>
    <!-- TODO:Described according to the environment-->

Reference: Password Encryption --Maven




#Initial processing
echo ''
echo '--------------------------------------------'
echo ' Init'
echo '--------------------------------------------'
#Settings / basic information
MAVEN_SETTING_DEST=`realpath ~/.m2/`
echo 'Basic information'
echo "Working directory: `pwd`"
echo "maven: `mvn --version`"

#Copy Maven config file
echo ''
echo '--------------------------------------------'
echo ' Copy Maven settings files'
echo '--------------------------------------------'
echo 'Copying will start.'
cp ./.devcontainer/settings.xml ./.devcontainer/settings-security.xml ${MAVEN_SETTING_DEST}
echo 'Copying is complete.'

#End processing
echo ''
echo '--------------------------------------------'
echo ' Exit'
echo '--------------------------------------------'
echo 'The process ends.'
exit 0

The shell specified by postCreateCommand in .devcontainer / devcontainer.json. It is hit after the container is created.

As for the contents, we have copied the Maven configuration files to the .m2 folder (/home/vscode/.m2) directly under the vscode user home. If this is all, I think you should write it directly in postCreateCommand of devcontainer.json without cutting it out to the shell ...: angel:

: rocket: start

All you have to do is start it normally! I will omit the details because it is different from the main line, but roughly ...

--Install the VS Code Remote --Containers (vscode: extension / ms-vscode-remote.remote-containers) extension and --Start Docker --VS Code asks "Is it possible to open it here in a container?", So Reopen in Container

is not it!

At this time, it seems that the .devcontainer folder should be directly under the root folder of the VS Code workspace.

: end: At the end

By the way ... I didn't have enough machine specs, so I finally gave up developing with this method: angel: However, I think it's very convenient because it makes it easier to build the environment at once, so if there is no problem with the specifications, I think you should definitely consider it positively!

I hope it helps people who are in Proxy environment + VS Code Remote Development + Java.

Well then!

: link: link

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