JSONAISTUDIO
Dev Containers · IDEbeginner

Dev Container (devcontainer.json)

A devcontainer.json that defines a reproducible Node.js dev environment for GitHub Codespaces and VS Code — base image, dev container features, forwarded ports, pre-installed extensions and a post-create setup step.

devcontainercodespacesvscodedockerenvironment

Preview

{
  "name": "Node.js Dev Container",
  "image": "mcr.microsoft.com/devcontainers/javascript-node:20-bookworm",
  "features": {
    "ghcr.io/devcontainers/features/github-cli:1": {},
    "ghcr.io/devcontainers/features/docker-in-docker:2": {
      "version": "latest",
      "moby": true
    }
  },
  "forwardPorts": [
    3000,
    5432
  ],
  "portsAttributes": {
    "3000": {
      "label": "app",
      "onAutoForward": "notify"
    },
    "5432": {
      "label": "postgres",
      "onAutoForward": "silent"
    }
  },
  "customizations": {
    "vscode": {
      "extensions": [
        "dbaeumer.vscode-eslint",
        "esbenp.prettier-vscode",
        "ms-azuretools.vscode-docker"
      ],
      "settings": {
        "editor.formatOnSave": true,
        "editor.defaultFormatter": "esbenp.prettier-vscode"
      }
    }
  },
  "postCreateCommand": "npm install",
  "remoteUser": "node"
}

AI actions

Documentation

Purpose

Describe a reproducible, containerized development environment so every contributor (and every Codespace) gets the same tools, ports and editor setup.

When to use

Onboarding a repo to GitHub Codespaces or VS Code Dev Containers, or standardizing "works on my machine" toolchains across a team.

Required fields

  • image OR build — the base container image, or a Dockerfile to build

Optional fields

  • features — reusable add-ons (docker-in-docker, language toolchains)
  • forwardPorts — container ports surfaced to your machine
  • customizations.vscode — extensions and settings applied on launch
  • postCreateCommand — a command run once after the container is created
  • remoteUser — the non-root user the IDE runs as

Best practices

  • Pin the base image and each feature to a version; do not float on latest.
  • Install dependencies in postCreateCommand so the image stays cacheable.
  • Run as a non-root remoteUser (e.g. node, vscode) rather than root.

Security considerations

  • Do not bake secrets into the image or devcontainer.json; use Codespaces secrets or env files.
  • docker-in-docker grants broad privileges — add it only when the workflow needs it.
  • Prefer official/verified feature sources over arbitrary third-party ones.

Related templates

Related articles