Prometheus - Monitoring System & Time Series Database

Overview

Kolla can deploy a full working Prometheus setup in either a all-in-one or multinode setup.

Preparation and deployment

To enable Prometheus, modify the configuration file /etc/kolla/globals.yml and change the following:

enable_prometheus: "yes"

Note: This will deploy Prometheus version 2.x. Any potentially existing Prometheus 1.x instances deployed by previous Kolla Ansible releases will conflict with current version and should be manually stopped and/or removed. If you would like to stay with version 1.x, set the enable_prometheus variable to no.

In order to remove leftover volume containing Prometheus 1.x data, execute:

docker volume rm prometheus

on all hosts wherever Prometheus was previously deployed.

Basic Auth

Prometheus is protected with basic HTTP authentication. Kolla-ansible will create the following users: admin and grafana (if grafana is enabled). The grafana username can be overidden using the variable prometheus_grafana_user. The passwords are defined by the prometheus_password and prometheus_grafana_password variables in passwords.yml. The list of basic auth users can be extended using the prometheus_basic_auth_users_extra variable:

prometheus_basic_auth_users_extra:
   - username: user
     password: hello
     enabled: true

or completely overriden with the prometheus_basic_auth_users variable.

Extending the default command line options

It is possible to extend the default command line options for Prometheus by using a custom variable. As an example, to set query timeout to 1 minute and data retention size to 30 gigabytes:

prometheus_cmdline_extras: "--query.timeout=1m --storage.tsdb.retention.size=30GB"

Configuration options

Configuration options

Option

Default

Description

prometheus_scrape_interval

60s

Default scrape interval for all jobs

Extending prometheus.cfg

If you want to add extra targets to scrape, you can extend the default prometheus.yml config file by placing additional configs in {{ node_custom_config }}/prometheus/prometheus.yml.d. These should have the same format as prometheus.yml. These additional configs are merged so that any list items are extended. For example, if using the default value for node_custom_config, you could add additional targets to scrape by defining /etc/kolla/config/prometheus/prometheus.yml.d/10-custom.yml containing the following:

scrape_configs:
  - job_name: custom
    static_configs:
      - targets:
        - '10.0.0.111:1234'
  - job_name: custom-template
    static_configs:
      - targets:
{% for host in groups['prometheus'] %}
        - '{{ hostvars[host][('ansible_' + hostvars[host]['api_interface'] | replace('-','_'))]['ipv4']['address'] }}:{{ 3456 }}'
{% endfor %}

The jobs, custom, and custom_template would be appended to the default list of scrape_configs in the final prometheus.yml. To customize on a per host basis, files can also be placed in {{ node_custom_config }}/prometheus/<inventory_hostname>/prometheus.yml.d where, inventory_hostname is one of the hosts in your inventory. These will be merged with any files in {{ node_custom_config }}/prometheus/prometheus.yml.d, so in order to override a list value instead of extending it, you will need to make sure that no files in {{ node_custom_config }}/prometheus/prometheus.yml.d set a key with an equivalent hierarchical path.

Extra files

Sometimes it is necessary to reference additional files from within prometheus.yml, for example, when defining file service discovery configuration. To enable you to do this, kolla-ansible will resursively discover any files in {{ node_custom_config }}/prometheus/extras and template them. The templated output is then copied to /etc/prometheus/extras within the container on startup. For example to configure ipmi_exporter, using the default value for node_custom_config, you could create the following files:

  • /etc/kolla/config/prometheus/prometheus.yml.d/ipmi-exporter.yml:

    ---
scrape_configs:
- job_name: ipmi
  params:
    module: ["default"]
    scrape_interval: 1m
    scrape_timeout: 30s
    metrics_path: /ipmi
    scheme: http
    file_sd_configs:
      - files:
          - /etc/prometheus/extras/file_sd/ipmi-exporter-targets.yml
    refresh_interval: 5m
    relabel_configs:
      - source_labels: [__address__]
        separator: ;
        regex: (.*)
        target_label: __param_target
        replacement: ${1}
        action: replace
      - source_labels: [__param_target]
        separator: ;
        regex: (.*)
        target_label: instance
        replacement: ${1}
        action: replace
      - separator: ;
        regex: .*
        target_label: __address__
        replacement: "{{ ipmi_exporter_listen_address }}:9290"
        action: replace

    where ipmi_exporter_listen_address is a variable containing the IP address of the node where the exporter is running.

  • /etc/kolla/config/prometheus/extras/file_sd/ipmi-exporter-targets.yml:

    ---
- targets:
  - 192.168.1.1
labels:
    job: ipmi_exporter

Metric Instance labels

Previously, Prometheus metrics used to label instances based on their IP addresses. This behaviour can now be changed such that instances can be labelled based on their inventory hostname instead. The IP address remains as the target address, therefore, even if the hostname is unresolvable, it doesn’t pose an issue.

The default behavior still labels instances with their IP addresses. However, this can be adjusted by changing the prometheus_instance_label variable. This variable accepts the following values:

  • None: Instance labels will be IP addresses (default)

  • {{ ansible_facts.hostname }}: Instance labels will be hostnames

  • {{ ansible_facts.nodename }}: Instance labels will FQDNs

To implement this feature, modify the configuration file /etc/kolla/globals.yml and update the prometheus_instance_label variable accordingly. Remember, changing this variable will cause Prometheus to scrape metrics with new names for a short period. This will result in duplicate metrics until all metrics are replaced with their new labels.

prometheus_instance_label: "{{ ansible_facts.hostname }}"

This metric labeling feature may become the default setting in future releases. Therefore, if you wish to retain the current default (IP address labels), make sure to set the prometheus_instance_label variable to None.

Note

This feature may generate duplicate metrics temporarily while Prometheus updates the metric labels. Please be aware of this while analyzing metrics during the transition period.