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 must install them yourself. Over subsequent releases additional GitLab metrics are captured.

Prometheus services are on by default with GitLab 9.0.

Prometheus and its exporters don't authenticate users, and are 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 through the various exporters. To view and work with the monitoring data, you can either connect directly to Prometheus or use a dashboard tool like Grafana.

Configuring Prometheus

For installations from source, you must install and configure it yourself.

Prometheus and its exporters are on by default, starting with GitLab 9.0. Prometheus runs as the gitlab-prometheus user and listen on http://localhost:9090. By default, Prometheus is only accessible from the GitLab server itself. Each exporter is 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:

Edit /etc/gitlab/gitlab.rb
Add or find and uncomment the following line, making sure it's set to false:
```
prometheus_monitoring['enable'] = false
```
Save the file and reconfigure GitLab for the changes to take effect.

Changing the port and address Prometheus listens on

WARNING: The following change was added in Omnibus GitLab 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.

To access Prometheus from outside the GitLab server, set an FQDN or IP in prometheus['listen_address']. To change the address/port that Prometheus listens on:

Edit /etc/gitlab/gitlab.rb
Add or find and uncomment the following line:
```
prometheus['listen_address'] = 'localhost:9090'
```
Replace localhost:9090 with the address or 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'
```
Save the file and reconfigure GitLab for the changes to take effect

Adding custom scrape configurations

You can configure additional scrape targets for the Omnibus GitLab-bundled Prometheus by editing prometheus['scrape_configs'] in /etc/gitlab/gitlab.rb using the Prometheus scrape target configuration syntax.

Here is an example configuration to scrape http://1.1.1.1:8060/probe?param_a=test&param_b=additional_test:

prometheus['scrape_configs'] = [
  {
    'job_name': 'custom-scrape',
    'metrics_path': '/probe',
    'params' => {
      'param_a' => ['test'],
      'param_b' => ['additional_test']
    },
    'static_configs' => [
      'targets' => ['1.1.1.1:8060'],
    ],
  },
]

Standalone Prometheus using Omnibus GitLab

The Omnibus GitLab package can be used to configure a standalone Monitoring node running Prometheus and Grafana.

The steps below are the minimum necessary to configure a Monitoring node running Prometheus and Grafana with Omnibus GitLab:

SSH into the Monitoring node.
Install the Omnibus GitLab package you want using steps 1 and 2 from the GitLab downloads page, but do not follow the remaining steps.
Make sure to collect the IP addresses or DNS records of the Consul server nodes, for the next step.

Edit /etc/gitlab/gitlab.rb and add the contents:

external_url 'http://gitlab.example.com'

# Enable Prometheus
prometheus['enable'] = true
prometheus['listen_address'] = '0.0.0.0:9090'
prometheus['monitor_kubernetes'] = false

# Enable Login form
grafana['disable_login_form'] = false

# Enable Grafana
grafana['enable'] = true
grafana['admin_password'] = 'toomanysecrets'

# Enable service discovery for Prometheus
consul['enable'] = true
consul['monitoring_service_discovery'] =  true

# The addresses can be IPs or FQDNs
consul['configuration'] = {
   retry_join: %w(10.0.0.1 10.0.0.2 10.0.0.3),
}

# Disable all other services
gitlab_rails['auto_migrate'] = false
alertmanager['enable'] = false
gitaly['enable'] = false
gitlab_exporter['enable'] = false
gitlab_workhorse['enable'] = false
nginx['enable'] = true
postgres_exporter['enable'] = false
postgresql['enable'] = false
redis['enable'] = false
redis_exporter['enable'] = false
sidekiq['enable'] = false
puma['enable'] = false
node_exporter['enable'] = false
gitlab_exporter['enable'] = false

Run sudo gitlab-ctl reconfigure to compile the configuration.

The next step is to tell all the other nodes where the monitoring node is:

Edit /etc/gitlab/gitlab.rb, and add, or find and uncomment the following line:
```
gitlab_rails['prometheus_address'] = '10.0.0.1:9090'
```
Where 10.0.0.1:9090 is the IP address and port of the Prometheus node.
Save the file and reconfigure GitLab for the changes to take effect.

After monitoring using Service Discovery is enabled with consul['monitoring_service_discovery'] = true, ensure that prometheus['scrape_configs'] is not set in /etc/gitlab/gitlab.rb. Setting both consul['monitoring_service_discovery'] = true and prometheus['scrape_configs'] in /etc/gitlab/gitlab.rb results in errors.

Using an external Prometheus server

WARNING: Prometheus and most exporters don't support authentication. We don't 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 GitLab deployments with multiple nodes.

To use an external Prometheus server:

Edit /etc/gitlab/gitlab.rb.
Disable the bundled Prometheus:
```
prometheus['enable'] = false
```

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

node_exporter['listen_address'] = '0.0.0.0:9100'
gitlab_workhorse['prometheus_listen_addr'] = "0.0.0.0:9229"

# Rails nodes
gitlab_exporter['listen_address'] = '0.0.0.0'
gitlab_exporter['listen_port'] = '9168'

# Sidekiq nodes
sidekiq['listen_address'] = '0.0.0.0'

# Redis nodes
redis_exporter['listen_address'] = '0.0.0.0:9121'

# PostgreSQL nodes
postgres_exporter['listen_address'] = '0.0.0.0:9187'

# Gitaly nodes
gitaly['prometheus_listen_addr'] = "0.0.0.0:9236"

Install and set up a dedicated Prometheus instance, if necessary, using the official installation instructions.
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']
```
On all GitLab Rails(Puma/Unicorn, Sidekiq) servers, set the Prometheus server IP address and listen port. For example:
```
gitlab_rails['prometheus_address'] = '192.168.0.1:9090'
```

To scrape NGINX metrics, you must also 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",
}

Reconfigure GitLab to apply the changes.
Edit the Prometheus server's configuration file.

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: nginx
    static_configs:
      - targets:
        - 1.1.1.1:8060
  - job_name: redis
    static_configs:
      - targets:
        - 1.1.1.1:9121
  - job_name: postgres
    static_configs:
      - targets:
        - 1.1.1.1:9187
  - job_name: node
    static_configs:
      - targets:
        - 1.1.1.1:9100
  - job_name: gitlab-workhorse
    static_configs:
      - targets:
        - 1.1.1.1:9229
  - job_name: gitlab-rails
    metrics_path: "/-/metrics"
    static_configs:
      - targets:
        - 1.1.1.1:8080
  - job_name: gitlab-sidekiq
    static_configs:
      - targets:
        - 1.1.1.1:8082
  - job_name: gitlab_exporter_database
    metrics_path: "/database"
    static_configs:
      - targets:
        - 1.1.1.1:9168
  - job_name: gitlab_exporter_sidekiq
    metrics_path: "/sidekiq"
    static_configs:
      - targets:
        - 1.1.1.1:9168
  - job_name: gitlab_exporter_process
    metrics_path: "/process"
    static_configs:
      - targets:
        - 1.1.1.1:9168
  - job_name: gitaly
    static_configs:
      - targets:
        - 1.1.1.1:9236

Reload the Prometheus server.

Viewing performance metrics

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

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 the 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 visualization.

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

Create a new data source in Grafana.
Name your data source (such as GitLab).
Select Prometheus in the type dropdown box.
Add your Prometheus listen address as the URL, and set access to Browser.
Set the HTTP method to GET.
Save and 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's available on the same URL and port as user traffic.

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.

Redis exporter

The Redis exporter allows you to measure various Redis metrics.

PostgreSQL exporter

The PostgreSQL exporter allows you to measure various PostgreSQL metrics.

PgBouncer exporter

The PgBouncer exporter allows you to measure various PgBouncer metrics.

Registry exporter

The Registry exporter allows you to measure various Registry metrics.

GitLab exporter

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

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 collects 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:

Edit /etc/gitlab/gitlab.rb.
Add (or find and uncomment) the following line and set it to false:
```
prometheus['monitor_kubernetes'] = false
```
Save the file and reconfigure GitLab for the changes to take effect.