What is Solid Queue?

Solid Queue is the default background job processing library for Rails 8. It uses your database (PostgreSQL®, MySQL®, or SQLite) to manage the job queue, eliminating the need for a separate Redis® OSS instance for many use cases.

Configuration for Rails 8

When using Solid Queue on Scalingo, you need to ensure that your database configuration in config/database.yml correctly references the DATABASE_URL environment variable for both the primary database and the queue database.

By default, Rails 8 might expect a separate database for the queue, but on Scalingo, you typically use the same database for both.

Update your config/database.yml:

production:
  primary: &default
    adapter: postgresql # or mysql2 (the adapter name for MySQL)
    encoding: unicode
    url: <%= ENV['DATABASE_URL'] %>
    pool: <%= ENV.fetch("RAILS_MAX_THREADS") { 5 } %>

  queue:
    <<: *default
    url: <%= ENV['DATABASE_URL'] %>

Adding “worker” container type in your Procfile

To process background jobs, you need to run the Solid Queue worker process. Add the following line to your Procfile:

worker: bin/jobs

Deployment

After updating your config/database.yml and Procfile, deploy your application:

git add config/database.yml Procfile
git commit -m "Configure Solid Queue for Scalingo"
git push scalingo master

Once deployed, you need to scale the worker container to at least 1 to start processing jobs:

scalingo --app my-app scale worker:1