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How do I use multiple databases with Rails on Hatchbox?

Does Hatchbox support Solid Queue, Solid Cache, and Solid Cable?

Written by Kent
Updated over a week ago
Rails now includes the Solid gems by default, each requiring a database connection.

To learn more about how Rails handles multiple databases in configuration and environment variables, check out this screencast:
https://gorails.com/episodes/how-to-configure-multiple-databases-with-rails

Multiple Databases with Rails

Out of the box, Rails 8 ships with a config/database.yml that has 4 databases:
  1. primary
  2. queue
  3. cache
  4. cable

SQLite

For SQLite, you don't have to do a thing! Your app's config/database.yml defines the path to where these SQLite databases are stored on disk. By default, they'll point to storage/db-name.sqlite. This directory is symlinked every deploy so each release has access to the databases.

PostgreSQL and MySQL

For Postgres and MySQL, you'll need to define a DATABASE_URL for each database in your config/database.yml.
  1. DATABASE_URL (or PRIMARY_DATABASE_URL)
  2. QUEUE_DATABASE_URL (for Solid Queue)
  3. CACHE_DATABASE_URL (for Solid Cache)
  4. CABLE_DATABASE_URL (for Solid Cable)
When you attach a database to an app in Hatchbox, it tries to set DATABASE_URL. If it's already defined, it will prefix a color like BLUE_DATABASE_URL so it doesn't conflict. You can rename these environment variables so you have one for each database.