Remotes

A remote coast runs your services on a remote machine instead of your laptop. The CLI and UI experience is identical to local coasts -- coast run, coast assign, coast exec, coast ps, and coast checkout all work the same way. The daemon detects that the instance is remote and routes operations through an SSH tunnel to coast-service on the remote host.

Local vs Remote

	Local Coast	Remote Coast
DinD container	Runs on your machine	Runs on the remote machine
Compose services	Inside local DinD	Inside remote DinD
File editing	Direct bind mount	Shell coast (local) + rsync/mutagen sync
Port access	socat forwarder	SSH -L tunnel + socat forwarder
Shared services	Bridge network	SSH -R reverse tunnel
Build architecture	Your machine's arch	Remote machine's arch

How It Works

Every remote coast creates two containers:

1. A shell coast on your local machine. This is a lightweight Docker container (sleep infinity) with the same bind mounts as a normal coast (/host-project, /workspace). It exists so host agents can edit files that sync to the remote.

2. A remote coast on the remote machine, managed by coast-service. This runs the actual DinD container with your compose services, using dynamic ports.

The daemon bridges them with SSH tunnels:

• Forward tunnels (ssh -L): map each local dynamic port to the corresponding remote dynamic port, so localhost:{dynamic} reaches the remote service.
• Reverse tunnels (ssh -R): expose local shared services (Postgres, Redis) to the remote DinD container.

Registering Remotes

Remotes are registered with the daemon and stored in state.db:

coast remote add my-vm ubuntu@10.0.0.1 --key ~/.ssh/coast_key
coast remote test my-vm
coast remote ls
coast remote rm my-vm

Connection details (host, user, port, SSH key) live in the daemon's database, not in your Coastfile. The Coastfile only declares sync preferences via the [remote] section.

Remote Builds

Builds happen on the remote machine so images use the remote's native architecture. An ARM Mac can build x86_64 images on an x86_64 remote without cross-compilation.

After building, the artifact is transferred back to your local machine for reuse. If another remote has the same architecture, the pre-built artifact can be deployed directly without rebuilding. See Builds for more on how build artifacts are structured.

File Sync

Remote coasts use rsync for initial bulk transfer and mutagen for continuous real-time sync. Both tools run inside coast containers (the shell coast and the coast-service image), not on your host machine. See the Remote Coasts guide for details on sync configuration.

Disk Management

Remote machines accumulate Docker volumes, workspace directories, and image tarballs. When coast rm removes a remote instance, all associated resources are cleaned up. For orphaned resources from failed operations, use coast remote prune.

Setup

For full setup instructions including host requirements, coast-service deployment, and Coastfile configuration, see the Remote Coasts guide.