Hey there, great question. Here is what is needed:

1. Create a new service in your Railway project using the same PowerSync Docker image (journeyapps/powersync-service)

2. IMPORTANT: Override the start command to: /bin/sh -c "exec node service/lib/entry.js compact"

3. In the service's Settings, set the Cron Schedule field — e.g. 0 3 * * * (daily at 3am UTC)

4. Ensure the service shares the same environment variables as your main PowerSync service (POWERSYNC_CONFIG_B64 and PS_POSTGRES_BUCKET_URL)

Note: The deployment on the new service created in your project will be marked as crashed with errors along the line of:

Attempted to substitute environment variable "PS_AUTH_JWKS" which is undefined. Set this variable on the environment. Attempted to substitute environment variable "PS_AUTH_AUD" which is undefined. Set this variable on the environment.

This is not such a big issue because we you don't want the service to start another PowerSync instance (replicator + API), you only want the new service to run the compact command on a schedule on the service.

When the CRON JOB starts it will use the correct command to call the compact function on the container and then the CRON run should pass. You can check the Cron Runs tab to view the history.

We'll also update the template to include this, thanks for bringing this up.