VSCode Remote Container - extensions not installing on dev container using docker-compose

Question

I am having trouble getting extensions installed in the dev container using "Remote - Containers". I do not know if it's a bug, incorrect configuration on my end, or intended behaviour. Down below is my current configuration, both files are located in the root folder of the project.

docker-compose.yml

version: "3.7"

services:
  api:
    image: node:12
    restart: always
    ports:
      - ${API_PORT}:3000
    volumes:
      - .:/usr/app
      - /usr/app/node_modules
    working_dir: /usr/app
    command: bash -c "yarn && yarn dev"

.devcontainer.json

{
    "dockerComposeFile": "docker-compose.yml",
    "service": "api",
    "workspaceFolder": "/usr/app",
    "extensions": [
        "eamodio.gitlens",
        "formulahendry.auto-rename-tag",
        "coenraads.bracket-pair-colorizer-2",
        "kumar-harsh.graphql-for-vscode",
        "esbenp.prettier-vscode",
        "ms-vscode.vscode-typescript-tslint-plugin",
        "visualstudioexptteam.vscodeintellicode"
    ]
}

The list of extensions listed in the .devontainer.json are the ones I want to have installed in the dev container. Any help is appreciated!

Answer 1

According to the Visual Studio Code documentation, the two files need to be located in a directory .devcontainer in the workspace root.

I still had issues installing the extensions while working from behind a corporate proxy. The solution was to give the container access to the proxy server:

If you use an authenticating proxy like Cntlm on your local machine, configure it to listen on 172.17.0.1 (the Docker interface). Then define the http_proxy and https_proxy environment variables for the container. For example, in devcontainer.json:

"containerEnv": { 
  "http_proxy": "http://172.17.0.1:3128",
  "https_proxy": "http://172.17.0.1:3128"
}

Or in docker-compose.yaml

services:
  devcontainer:
    environment:
      http_proxy: http://172.17.0.1:3128
      https_proxy: http://172.17.0.1:3128

Or configure docker-compose.yaml to make the container use the host network:

services:
  devcontainer:
    network_mode: host

Then you can just pass the same proxy variables into the container as used on the host. For example, in the docker-compose.yaml:

services:
  devcontainer:
    environment:
      http_proxy: $http_proxy
      https_proxy: $https_proxy

If you are not using a local, but rather a remote proxy inside of your network, you can do the latter regardless of the container's network configuration (host or default).