12.1.1 Dev Containers

Dev containers are a specific, standardized way of defining a complete, containerized development environment — including not just the application's runtime but also editor extensions, tools, and configuration — designed to be opened directly by a supporting editor or IDE for a fully integrated development experience.

Defining a Dev Container Configuration

A devcontainer.json file describes the container environment an editor should use for development, often referencing an existing Dockerfile or Compose file.

{
  "name": "My App Dev Container",
  "dockerComposeFile": "docker-compose.yml",
  "service": "app",
  "workspaceFolder": "/app"
}

Why Dev Containers Go Beyond a Simple Bind-Mounted Container

A dev container configuration can also specify editor extensions to automatically install, environment-specific settings, and post-creation setup commands, providing a more complete, integrated environment than a bare bind-mounted container alone.

{
  "customizations": {
    "vscode": {
      "extensions": ["dbaeumer.vscode-eslint", "esbenp.prettier-vscode"]
    }
  },
  "postCreateCommand": "npm install"
}

This ensures every developer opening this dev container gets the same editor extensions and automatically runs the same setup command, beyond what the underlying container image alone would provide.

Opening a Project as a Dev Container

A supporting editor recognizes this configuration and offers to open the project directly inside the defined containerized environment.

code .

With an appropriate dev container configuration present, the editor can detect it and offer to reopen the project inside this fully configured container.

Why Dev Containers Provide a More Complete Experience

Beyond just running the application in a container, dev containers extend this consistency to the development tooling itself — extensions, settings, setup commands — providing an even more complete, reproducible development experience.

Why Dev Containers Matter

This standardized approach to defining a complete development environment, including editor integration, provides one of the most thorough and convenient ways to achieve genuinely consistent, low-friction onboarding and development across a team.