This gem is being sunset. Puma 5.0+ now configures Puma in most of the ways that this plugin did.

1. Upgrade to Puma 5.0.
2. Add port ENV['PORT'] || 3000 to your Puma config file, or -p ${PORT:-3000} to your puma invocation in your Procfile.
3. Remove this gem.

In 1.x, this plugin set workers to 1 if WEB_CONCURRENCY is not set. However, this isn't optimal, as it creates a master and worker process, when instead we could just use single mode (workers 0) and save memory. 2.x of this plugin uses the Puma 5 default, which is workers 0 if WEB_CONCURRENCY is not set.

If you are using Rails 4.0 or less, you will have to add your own on_worker_boot block., it has been removed.

As of Puma 5.0/this plugin 2.x, all this gem does is set the port to ENV["PORT"]. In Puma 6.0, Puma will listen to ENV["PORT"] by default, and this plugin will receive no further updates (because all of its changes will be merged into the Puma default config).

The gem is available as open source under the terms of the MIT License.