Dev Containers

Intercepts VS Code workspace initialization to redirect all tool execution, extension runtime, and terminal sessions into a Docker container while maintaining the local VS Code UI. Uses Docker volume mounts to bind local filesystem paths into the container, enabling seamless file synchronization between host and container without explicit copying. The extension manages container lifecycle (launch, attach, cleanup) and transparently proxies all workspace operations through the container's runtime environment.

Enables reproducible development environments through a declarative JSON schema (devcontainer.json) that specifies base container image, pre-installed tools, VS Code extensions, environment variables, port forwarding, and post-creation setup scripts. The extension parses this configuration at workspace open time and automatically provisions the container with all declared dependencies, eliminating manual tool installation and configuration drift across team members. Supports inheritance and composition patterns for reusable environment templates.

Supports composition of devcontainer.json from reusable templates and features published in registries, enabling modular environment configuration. Templates provide pre-configured devcontainer.json for common stacks (Node.js, Python, Go, etc.), while features add specific tools/runtimes (Docker-in-Docker, GitHub CLI, etc.) without duplicating configuration. Handles feature installation and dependency resolution automatically.

Automatically detects workspace folders and project structure, locating devcontainer.json in project root or .devcontainer/ directory. Supports multi-folder workspaces with per-folder devcontainer configurations. Provides context about workspace paths (${workspaceFolder}, ${containerWorkspaceFolder}) for use in environment variables, mount configurations, and post-creation scripts.

Abstracts Docker daemon connectivity across Windows (WSL2 backend), macOS (Docker Desktop), and Linux (native Docker) by automatically detecting the host OS and configuring appropriate Docker socket/daemon connection. Handles platform-specific filesystem mounting strategies (bind mounts on Linux, virtualized mounts on Windows/macOS) and manages architecture-specific container image selection (x86_64, ARMv7l, ARMv8l). Enables seamless container execution regardless of host OS without requiring developers to understand Docker daemon configuration.

Redirects VS Code extension execution from the host machine into the container environment by installing extension dependencies and native binaries inside the container and proxying extension API calls through the container runtime. Manages extension compatibility by detecting which extensions support container execution and automatically installing compatible versions inside the container. Maintains extension state synchronization between host and container for settings and configuration.

Enables connection to Docker daemons running on remote machines (e.g., cloud VMs, CI/CD servers) via SSH or direct TCP socket configuration, allowing container execution on remote infrastructure while maintaining local VS Code UI. Handles SSH key authentication, port forwarding, and daemon availability detection. Supports both persistent remote Docker hosts and ephemeral container-based development environments.

Mounts local workspace files into running containers using Docker volume mounts (bind mounts on Linux, virtualized mounts on Windows/macOS) with automatic path translation and permission handling. Supports selective file mounting via mount configuration, enabling developers to exclude large directories (node_modules, .git) from mounts to improve performance. Handles file permission mapping between host and container user accounts to prevent permission errors.

Automatically manages Docker container lifecycle including creation, startup, health checking, and cleanup. Handles container reuse (attaching to existing containers vs. creating new ones), graceful shutdown on workspace close, and orphaned container detection. Provides status indicators in VS Code status bar showing container connection state and allows manual container restart/rebuild via command palette.

Automatically configures port forwarding from container ports to host localhost, enabling access to services running inside containers (web servers, databases, APIs) from the host machine. Supports dynamic port allocation (if host port is unavailable) and port mapping configuration via devcontainer.json. Provides port forwarding status in VS Code UI with clickable links to access exposed services.

Injects environment variables into container runtime from devcontainer.json 'remoteEnv' configuration, .env files, or host environment. Supports variable substitution and interpolation (e.g., ${workspaceFolder}, ${containerWorkspaceFolder}). Manages environment variable scope (container-wide vs. extension-specific) and provides environment variable visibility in VS Code terminal sessions.

Executes shell scripts (postCreateCommand, postStartCommand, postAttachCommand) inside containers after creation, startup, or attachment to automate setup tasks (dependency installation, database migrations, code generation). Scripts run with container user privileges and have access to mounted workspace and container environment. Supports both single-command strings and multi-line scripts via shell syntax.