Environment variables

Variables live in .env at the repository root (or /opt/claude-sandbox/.env on a deployed host). Compose reads them at start; nothing else does.

Worker

Variable	Required	Consumed by	Purpose
ANTHROPIC_ENVIRONMENT_KEY	yes	worker	Environment key (sk-ant-oat01-...) that authenticates the worker to its work queue. Console-generated, queue-scoped.
ANTHROPIC_ENVIRONMENT_ID	yes	worker	The self_hosted environment’s identifier.
ANTHROPIC_BASE_URL	no	worker	API base override, passed through only when set.

Caution

Never set ANTHROPIC_API_KEY on the worker host. Agent tool calls can read the worker’s environment, and the API key is organization-scoped. The upstream integration guide carries the same warning.

Tunnel and publisher

Variable	Required	Consumed by	Purpose
MCP_TUNNEL_PORT	no, default 8787	compose port mapping	Loopback port the tunnel publishes on the host.
CLOUDFLARE_TUNNEL_TOKEN	only with the cloudflared profile	cloudflared	Token-mode tunnel credential from the Zero Trust dashboard.

Launcher

Variable	Required	Consumed by	Purpose
CLAUDE_SANDBOX_DIR	no	install.sh	Clone destination, default ~/code/systemd-claude-sandbox.
CLAUDE_SANDBOX_MODE	no	install.sh	Skips detection: compose, devcontainer, bare, or wsl.

Session environment inside sandboxes

The worker exports these to each spawned session; you do not set them yourself: ANTHROPIC_SESSION_ID, ANTHROPIC_WORK_ID, ANTHROPIC_ENVIRONMENT_ID, ANTHROPIC_ENVIRONMENT_KEY, and ANTHROPIC_BASE_URL when present on the poller.