Container Configuration

.devcontainer/devcontainer.json controls the container itself.

Use it when you want to change:

the base image
resource limits
installed DevContainer features
forwarded ports
optional runtimes and tools

Base Image and Resources

Example:

{
  "image": "mcr.microsoft.com/devcontainers/python:3.14",
  "runArgs": ["--memory=6g", "--memory-swap=12g"],
  "remoteUser": "vscode",
  "containerUser": "vscode"
}

Features

Features install runtimes and tools into the container.

{
  "features": {
    "ghcr.io/devcontainers/features/node:1.7.1": { "version": "lts" },
    "./features/claude-code-native": {},
    "./features/ruff": { "version": "latest" }
  }
}

For local features, setting "version": "none" disables the feature without removing it.

Ports

Port behavior is configured in devcontainer.json, but how it works depends on the client.

Use Accessing Services for the practical client-by-client guide.

Rebuild Expectations

Changing devcontainer.json usually requires a rebuild.

use a normal rebuild for routine changes
use a no-cache rebuild when the first build was interrupted or a feature install is corrupted

What This Page Does Not Cover

This page focuses on the container itself. For runtime Claude behavior, use Settings and Permissions.