Monitoring GitLab with Prometheus

Notes:

  • Prometheus and the various exporters listed in this page are bundled in the Omnibus GitLab package. Check each exporter’s documentation for the timeline they got added. For installations from source you will have to install them yourself. Over subsequent releases additional GitLab metrics will be captured.
  • Prometheus services are on by default with GitLab 9.0.
  • Prometheus and its exporters do not authenticate users, and will be available to anyone who can access them.

Prometheus is a powerful time-series monitoring service, providing a flexible platform for monitoring GitLab and other software products. GitLab provides out of the box monitoring with Prometheus, providing easy access to high quality time-series monitoring of GitLab services.

Overview

Prometheus works by periodically connecting to data sources and collecting their performance metrics via the various exporters. To view and work with the monitoring data, you can either connect directly to Prometheus or utilize a dashboard tool like Grafana.

Configuring Prometheus

Note: For installations from source you’ll have to install and configure it yourself.

Prometheus and its exporters are on by default, starting with GitLab 9.0. Prometheus will run as the gitlab-prometheus user and listen on http://localhost:9090. By default Prometheus is only accessible from the GitLab server itself. Each exporter will be automatically set up as a monitoring target for Prometheus, unless individually disabled.

To disable Prometheus and all of its exporters, as well as any added in the future:

  1. Edit /etc/gitlab/gitlab.rb

  2. Add or find and uncomment the following line, making sure it’s set to false:

     prometheus_monitoring['enable'] = false
  3. Save the file and reconfigure GitLab for the changes to take effect.

Changing the port and address Prometheus listens on

Note: The following change was added in GitLab Omnibus 8.17. Although possible, it’s not recommended to change the port Prometheus listens on as this might affect or conflict with other services running on the GitLab server. Proceed at your own risk.

In order to access Prometheus from outside the GitLab server you will need to set a FQDN or IP in prometheus['listen_address']. To change the address/port that Prometheus listens on:

  1. Edit /etc/gitlab/gitlab.rb

  2. Add or find and uncomment the following line:

     prometheus['listen_address'] = 'localhost:9090'

    Replace localhost:9090 with the address/port you want Prometheus to listen on. If you would like to allow access to Prometheus to hosts other than localhost, leave out the host, or use 0.0.0.0 to allow public access:

     prometheus['listen_address'] = ':9090'
 # or
 prometheus['listen_address'] = '0.0.0.0:9090'
  3. Save the file and reconfigure GitLab for the changes to take effect

Using an external Prometheus server

Note: Prometheus and most exporters do not support authentication. We do not recommend exposing them outside the local network.

A few configuration changes are required to allow GitLab to be monitored by an external Prometheus server. External servers are recommended for highly available deployments of GitLab with multiple nodes.

To use an external Prometheus server:

  1. Edit /etc/gitlab/gitlab.rb.

  2. Disable the bundled Prometheus:

     prometheus['enable'] = false

  3. Set each bundled service’s exporter to listen on a network address, for example:

      gitlab_monitor['listen_address'] = '0.0.0.0'
  sidekiq['listen_address'] = '0.0.0.0'
  gitlab_monitor['listen_port'] = '9168'
  node_exporter['listen_address'] = '0.0.0.0:9100'
  redis_exporter['listen_address'] = '0.0.0.0:9121'
  postgres_exporter['listen_address'] = '0.0.0.0:9187'
  gitaly['prometheus_listen_addr'] = "0.0.0.0:9236"
  gitlab_workhorse['prometheus_listen_addr'] = "0.0.0.0:9229"
  4. Install and set up a dedicated Prometheus instance, if necessary, using the official installation instructions.

  5. Add the Prometheus server IP address to the monitoring IP whitelist. For example:

     gitlab_rails['monitoring_whitelist'] = ['127.0.0.0/8', '192.168.0.1']

  6. To scrape nginx metrics, you’ll also need to configure nginx to allow the Prometheus server IP. For example:

     nginx['status']['options'] = {
       "server_tokens" => "off",
       "access_log" => "off",
       "allow" => "192.168.0.1",
       "deny" => "all",
 }
  7. Reconfigure GitLab to apply the changes
  8. Edit the Prometheus server’s configuration file.

  9. Add each node’s exporters to the Prometheus server’s scrape target configuration. For example, a sample snippet using static_configs:

     scrape_configs:
 - job_name: 'gitlab_exporters'
   static_configs:
   - targets: ['1.1.1.1:9168', '1.1.1.1:9236', '1.1.1.1:9236', '1.1.1.1:9100', '1.1.1.1:9121', '1.1.1.1:9187']

 - job_name: 'gitlab_metrics'
   metrics_path: /-/metrics
   static_configs:
   - targets: ['1.1.1.1:443']
  10. Restart the Prometheus server.

Viewing performance metrics

You can visit http://localhost:9090 for the dashboard that Prometheus offers by default.

Note: If SSL has been enabled on your GitLab instance, you may not be able to access Prometheus on the same browser as GitLab if using the same FQDN due to HSTS. We plan to provide access via GitLab, but in the interim there are some workarounds: using a separate FQDN, using server IP, using a separate browser for Prometheus, resetting HSTS, or having NGINX proxy it.

The performance data collected by Prometheus can be viewed directly in the Prometheus console or through a compatible dashboard tool. The Prometheus interface provides a flexible query language to work with the collected data where you can visualize their output. For a more fully featured dashboard, Grafana can be used and has official support for Prometheus.

Sample Prometheus queries:

  • % Memory available: ((node_memory_MemAvailable_bytes / node_memory_MemTotal_bytes) or ((node_memory_MemFree_bytes + node_memory_Buffers_bytes + node_memory_Cached_bytes) / node_memory_MemTotal_bytes)) * 100
  • % CPU utilization: 1 - avg without (mode,cpu) (rate(node_cpu_seconds_total{mode="idle"}[5m]))
  • Data transmitted: rate(node_network_transmit_bytes_total{device!="lo"}[5m])
  • Data received: rate(node_network_receive_bytes_total{device!="lo"}[5m])

Prometheus as a Grafana data source

Grafana allows you to import Prometheus performance metrics as a data source and render the metrics as graphs and dashboards which is helpful with visualisation.

To add a Prometheus dashboard for a single server GitLab setup:

  1. Create a new data source in Grafana.
  2. Name your data source i.e GitLab.
  3. Select Prometheus in the type drop down.
  4. Add your Prometheus listen address as the URL and set access to Browser.
  5. Set the HTTP method to GET.
  6. Save & Test your configuration to verify that it works.

GitLab metrics

Introduced in GitLab 9.3.

GitLab monitors its own internal service metrics, and makes them available at the /-/metrics endpoint. Unlike other exporters, this endpoint requires authentication as it is available on the same URL and port as user traffic.

➔ Read more about the GitLab Metrics.

Bundled software metrics

Many of the GitLab dependencies bundled in Omnibus GitLab are preconfigured to export Prometheus metrics.

Node exporter

The node exporter allows you to measure various machine resources such as memory, disk and CPU utilization.

➔ Read more about the node exporter.

Redis exporter

The Redis exporter allows you to measure various Redis metrics.

➔ Read more about the Redis exporter.

Postgres exporter

The Postgres exporter allows you to measure various PostgreSQL metrics.

➔ Read more about the Postgres exporter.

PgBouncer exporter

The PgBouncer exporter allows you to measure various PgBouncer metrics.

➔ Read more about the PgBouncer exporter.

GitLab monitor exporter

The GitLab monitor exporter allows you to measure various GitLab metrics, pulled from Redis and the database.

➔ Read more about the GitLab monitor exporter.

Configuring Prometheus to monitor Kubernetes

Introduced in GitLab 9.0. Pod monitoring introduced in GitLab 9.4.

If your GitLab server is running within Kubernetes, Prometheus will collect metrics from the Nodes and annotated Pods in the cluster, including performance data on each container. This is particularly helpful if your CI/CD environments run in the same cluster, as you can use the Prometheus project integration to monitor them.

To disable the monitoring of Kubernetes:

  1. Edit /etc/gitlab/gitlab.rb.

  2. Add or find and uncomment the following line and set it to false:

     prometheus['monitor_kubernetes'] = false
  3. Save the file and reconfigure GitLab for the changes to take effect.