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Example of Rails, Sidekiq and Puma metrics exported to Prometheus + Grafana

This example illustrates how to use yabeda gem suite with rails application to draw graphs for app metrics.

Prerequisites

Recent versions of Docker and Docker Compose installed.

Usage

• Execute docker-compose up to start.
• Go to rails application at http://localhost:5000
• Hit the button and refresh page few times
• Go to Grafana Web UI at localhost (user: admin/admin)
• Look for graphs
• After starting up docker-compose will run rails-stressor service to simulate huge load for the rails app. By default will do the request for 2 minutes. Settings could be changed in docker-compose.yml config (command parameter of the rails_stressor service).

You also could run rails stressor again by executing docker-compose up rails_stressor command.

Notes

• Sample Rails application is equipped with yabeda-rails, yabeda-sidekiq, yabeda-puma-plugin, and yabeda-prometheus gems and properly configured.
• Raw rails metrics are exposed at http://localhost:5000/metrics
• Raw sidekiq metrics are exposed at http://localhost:5100/metrics
• Raw puma metrics are exposed at http://localhost:5100/metrics
• The Prometheus Web UI runs at http://localhost:9090
• The Grafana Web UI runs at http://localhost:3000 , user: admin/admin.
• The Sidekiq Web UI is available at http://localhost:5000/sidekiq

Possible errors and their solutions

Permission denied error / My grafana container is not running (Stopping after boot)

If your grafana's container is not running correctly after you run docker-compose up you're probably getting this error, if you check at docker ps -a you'll see your grana container with the status Exited, picks the id of this container and run docker logs YOUR_GRAFANA_CONTAINER_ID and check if the errors is equal to the following:

GF_PATHS_DATA='/var/lib/grafana' is not writable.
You may have issues with file permissions, more information here: http://docs.grafana.org/installation/docker/#migration-from-a-previou
s-version-of-the-docker-container-to-5-1-or-later
mkdir: cannot create directory '/var/lib/grafana/plugins': Permission denied

Solution

Replace at your docker-compose.yml line 38 by your user's id that you will get on the following command:

id -u

Acknowledgement

The configurations are based off the following articles and repositories:

• https://finestructure.co/blog/2016/5/16/monitoring-with-prometheus-grafana-docker-part-1
• https://github.com/NikolajLeischner/local-prometheus-grafana
• https://www.digitalocean.com/community/tutorials/how-to-add-a-prometheus-dashboard-to-grafana

License

This example is available as open source under the terms of the MIT License.