Docker Sandbox

What is the Docker Sandbox?

The Docker sandbox runs Copilot in an isolated Docker container. This provides:

• Filesystem isolation — Container can’t access host filesystem
• Network isolation — Limited network access
• Resource limits — CPU and memory constraints
• Clean environment — No access to host credentials

Enabling the Sandbox

Per-Dispatch

rally dispatch issue 42 --sandbox

Configuration

~/rally/config.yaml

settings:
  docker_sandbox: always    # Always use sandbox
  docker_sandbox: ask       # Ask each time (default)
  docker_sandbox: never     # Never use sandbox

Requirements

• Docker installed and running
• User in the docker group (or using sudo)

# Add yourself to docker group
sudo usermod -aG docker $USER
# Log out and back in

What Runs in the Container?

The container includes:

• Node.js runtime
• Git
• GitHub CLI (gh)
• Copilot CLI

The project worktree is mounted into the container.

Tool Restrictions in Sandbox

The sandbox uses a separate deny list:

settings:
  deny_tools_sandbox:
    - bash          # Still restricted

By default, the sandbox is more permissive than normal mode since the container provides isolation.

Limitations

• Slower startup — Container initialization adds overhead
• Limited tools — Only tools in the container image
• Mount restrictions — Some paths may not be accessible

When to Use Sandbox

Use the sandbox when:

• Working with untrusted code
• Running on shared machines
• Experimenting with risky changes

Normal mode is fine when:

• Working on your own code
• You trust the repository
• You need faster iteration