Task: Prometheus Metrics - Update

[jonrandahl]

Implement improvements from other applications and documented in the internal wiki:

Definition of Done

• Add Puma-metrics Gem
• Update config/puma.rb to include metrics plugin and port info
• Update config/initializers/prometheus.rb to add Middleware instrumentation
• Update config.ru to ensure prometheus is not triggered in the test environment
• Update app/subscribers/action_controller_prometheus_subscriber.rb
• Update the prometheus metrics notification to the application exceptions controller¹
• Update the puma-stats to display in the footer while in development
• Add the Prometheus monitoring information to the project README/WIKI

Footnotes

1. https://github.com/epimorphics/front-end-templates/blob/main/prometheus-metrics/README.md#add-the-prometheus-metrics-to-the-application-exceptions-controller ↩

[jonrandahl]

As this repository has had the information previously held in the README moved to the WIKI, the prometheus monitoring information is now here:
https://github.com/epimorphics/ppd-explorer/wiki#prometheus-monitoring

[jonrandahl]

Also, due to the Landing page, PPD, and Standard Reports loading their templates from the LR Common Styles gem, the changes for the puma-stats to be displayed in the footer while in development have required a new gem version and release: v1.9.9