# Run Companion on a server with Docker (https://www.getfounderhq.com/docs/companion/run-on-a-server-with-docker)

Start Companion on a Linux server that has Docker, and pair it from a link.
About 3 minutes. Docker starts it again after a crash or a reboot.

<Callout title="Before you start">
  You need a Linux server with Docker (64-bit Intel/AMD or ARM) and a
  FounderHQ account. No Docker? See
  [a server without Docker](/companion/run-on-a-server-without-docker).
</Callout>

## Start Companion

1. Start the container.

   ```bash
   docker run -d --name founderhq-companion --restart unless-stopped \
     -v founderhq-companion:/data ghcr.io/founderhq/founderhq-companion
   ```

   - `-v founderhq-companion:/data` keeps the pairing and the caption model
     in a volume, so an update does not unpair the server.
   - `--restart unless-stopped` starts Companion again after a crash and
     when the server boots.
2. Read the logs.

   ```bash
   docker logs -f founderhq-companion
   ```

   The log shows a link and a code between two lines of dashes, under
   **Pair this server with FounderHQ**.
3. Open the link in any browser where you are signed in to FounderHQ. Check
   that the code on the page matches the code in the log, then approve.
4. Press Ctrl+C to leave the log. Companion keeps running: the command only
   shows the log.

The log says how long the code works. Companion prints a new one after
that.

## Verify

The log shows `Ready for AI requests.`

In FounderHQ, open [Settings → Companion Apps](https://app.getfounderhq.com/?openSettings=companion). The server is in
the list and shows **Active now**.

## Update

Companion writes a line in the log when a new version is available. Pull
the new image and start the container again with the same volume.

```bash
docker pull ghcr.io/founderhq/founderhq-companion
docker rm -f founderhq-companion
docker run -d --name founderhq-companion --restart unless-stopped \
  -v founderhq-companion:/data ghcr.io/founderhq/founderhq-companion
```

The server stays paired.

## Unpair

In FounderHQ, open [Settings → Companion Apps](https://app.getfounderhq.com/?openSettings=companion), and unpair the
server. Companion notices the next time it connects, and prints a new
pairing link.

You can also unpair from the server:

```bash
docker exec founderhq-companion founderhq-companion-headless --unpair
```

## Troubleshoot

### "The data folder /data is not writable by this container's user"

You mounted a folder of the server at `/data`, and it belongs to root. Use
a named volume, as in the command above. To keep the folder, give it to
the container's user:

```bash
sudo chown 1000 /path/to/your/folder
```

### "this container cannot create user namespaces"

This is a note, and Companion works. The browser engine inside Companion
isolates the pages it draws, and Docker's default settings do not allow
that. Companion then draws them without that isolation. The pages are your
FounderHQ pages, and the public pages you ask FounderHQ to read.

See [Server settings](/companion/server-settings) for the other options.