Remote Daemons

Some setups keep containers on a separate machine: a Docker host next to the web servers, or one daemon shared by several apps. The same commands run there. Docker's CLI already knows how to talk to a remote daemon, and the package passes the address through.

Globally, in .env:

COMPOSE_DOCKER_HOST=ssh://deploy@docker-box

That value is what DOCKER_HOST accepts: ssh://user@host, tcp://host:2376, or unix:///path/to/socket. For SSH, the deploy user needs a key that the remote user accepts, and the remote user has to be in that machine's docker group.

Or name a docker context you created with docker context create:

COMPOSE_DOCKER_CONTEXT=docker-box

A single stack can override through host() or context(), so one app can run a search index locally and a browser farm elsewhere. A stack that sets either one replaces both global values, so a stack host() under a global context talks to that host, not the context. When a host and a context meet at the same level, the context wins and the host is dropped; that's Docker's own rule (--context overrides DOCKER_HOST), applied before the command runs instead of silently by the CLI. A unix:// or npipe:// host and the default context still count as the local machine.

• The operator link is skipped. A link on the web server would point at a directory the remote daemon can't see.
• Bind mounts don't exist there. ./Caddyfile:/etc/caddy/Caddyfile refers to a path on the machine running the command, and the remote daemon has no such file. The doctor warns about every bind mount in a stack with a remote daemon. Use named volumes, or bake the file into an image.
• The app reaches the container over the network. Publish the port on the private interface of the Docker host, never on 0.0.0.0. Docker bypasses host firewalls, so a public publish is a public port.
• The compose file and env file stay local. Compose reads both on the machine running the command and sends the resolved configuration to the daemon. Secrets travel over the SSH or TLS connection you configured, not through a file on the remote host.

php artisan compose:doctor

The daemon check runs against the remote and prints its version and the address it reached. A wrong key or a missing docker group membership shows up here, with the reason Docker gave.