OpenCode on Cubeship

OpenCode is an open-source AI coding agent: it reads and edits code, runs shell commands, and works with models from Anthropic, OpenAI, Google, OpenRouter and many other providers.

This template installs its server on a Cubeship instance, with the web UI on a domain, its sessions and settings in one volume and the code it works on in another.

This puts a coding agent that runs shell commands on the internet. Anyone with the password can make it run anything inside its container, read every file in its volumes, use your provider keys, and reach the other apps on the instance. Read Its server is on the internet before installing.

What it creates

• opencode — OpenCode 1.18.30, built on the instance from the Dockerfile in this repository. The web UI and the server's API answer on the domain you choose, behind a password. Two volumes:
  • /root — its config (.config/opencode), provider keys and sessions (.local/share/opencode), and whatever else you keep in the home directory, like .ssh and .gitconfig.
  • /workspace — the code it works on.

It needs Cubeship 0.7.0 or newer, and an admin to install it: the app is built on the instance, and only admins build.

Why it is built

The published image, ghcr.io/anomalyco/opencode, runs opencode, which starts the terminal UI and cannot run without a terminal. Cubeship runs an image's own command, so the Dockerfile here is that image running opencode serve on port 4096, with git and an SSH client added and /workspace as its working directory. The server is the same one the terminal UI talks to, and it serves the web UI too.

What you are asked

Input	What to give
Where OpenCode answers	A domain you control, pointed at your instance.
The password you sign in with	Nothing — the instance generates it and shows it once. Keep a copy.

The username is opencode. Set OPENCODE_SERVER_USERNAME on the app to change it.

No model provider key is asked for. Add one in OpenCode instead: it is written to the volume, and a key the template set would be an empty variable on the app whenever you left it blank.

After installing

1. Open the domain and sign in as opencode with the generated password.

2. Connect a provider: run /connect and choose one. Keys are kept in /root/.local/share/opencode/auth.json. A provider's usual variable, like ANTHROPIC_API_KEY, set on the app works too.

3. Give it code. Open a terminal in the web UI, or ask OpenCode to run the commands itself — Cubeship has no console into an app — and clone into /workspace:

   git config --global user.name "Your Name"
   git config --global user.email you@example.com
   cd /workspace && git clone https://github.com/you/project.git
   

   For private repositories, create a key with ssh-keygen -t ed25519 and add /root/.ssh/id_ed25519.pub to the repository as a deploy key. Both survive deploys: they are in the /root volume.

4. Open the project's directory in the web UI and start a session.

From your own terminal

The terminal UI on your laptop can use this server instead of its own:

OPENCODE_SERVER_PASSWORD=<the password> opencode attach https://<your domain>

The code, the shell commands and the keys stay on the instance.

Its server is on the internet

OpenCode's server has one account and one password, sent as HTTP basic auth, and no rate limit on guessing it. Behind that password is a shell: OpenCode runs its commands as root inside the container, with no sandbox beyond the container itself. It has no Docker socket and cannot reach the host, but it can reach the internet and every other app on the instance at its internal address.

• Keep the generated password, or use a longer one. Never an easy one.
• Keep the domain to yourself, and give the password to nobody you would not give a shell to.
• Keep only the credentials it needs on it: a deploy key per repository rather than your own SSH key, and a provider key with a spending limit.
• Remember what it can reach. An agent told to run something by a file it read — a README, an issue, a web page — will try to.
• Uninstall it when you stop using it.

OpenCode's permission settings, which decide what it asks before doing, are a guard against mistakes, not against someone who has the password: whoever signs in can change them.

Updating OpenCode

The OpenCode version is the FROM line of the Dockerfile, at the ref the template builds. OpenCode's own upgrade cannot replace the binary in a built image; a new release of this template can.

The volumes

The app runs as one copy on the machine its volumes are on, and a deploy stops it for a few seconds: a session running at that moment is cut off. Back both volumes up from the app's settings — the provider keys are in /root, and work not pushed anywhere is only in /workspace.

Resources

The app is limited to 2 CPUs and 4 GiB of memory. Language servers, builds and tests run inside it too: raise limits in template.yaml for large projects.