Ansible Role: prometheus

Description

Deploy Prometheus monitoring system using ansible.

Upgradability notice

When upgrading from <= 2.4.0 version of this role to >= 2.4.1 please turn off your prometheus instance. More in 2.4.1 release notes

Requirements

• Ansible >= 2.7 (It might work on previous versions, but we cannot guarantee it)
• jmespath on deployer machine. If you are using Ansible from a Python virtualenv, install jmespath to the same virtualenv via pip.
• gnu-tar on Mac deployer host (brew install gnu-tar)

Role Variables

All variables which can be overridden are stored in defaults/main.yml file as well as in table below.

Relation between prometheus_scrape_configs and prometheus_targets

Short version

prometheus_targets is just a map used to create multiple files located in "{{ prometheus_config_dir }}/file_sd" directory. Where file names are composed from top-level keys in that map with .yml suffix. Those files store file_sd scrape targets data and they need to be read in prometheus_scrape_configs.

Long version

A part of prometheus.yml configuration file which describes what is scraped by prometheus is stored in prometheus_scrape_configs. For this variable same configuration options as described in prometheus docs are used.

Meanwhile prometheus_targets is our way of adopting prometheus scrape type file_sd. It defines a map of files with their content. A top-level keys are base names of files which need to have their own scrape job in prometheus_scrape_configs and values are a content of those files.

All this mean that you CAN use custom prometheus_scrape_configs with prometheus_targets set to {}. However when you set anything in prometheus_targets it needs to be mapped to prometheus_scrape_configs. If it isn't you'll get an error in preflight checks.

Example

Lets look at our default configuration, which shows all features. By default we have this prometheus_targets:

prometheus_targets:
  node:  # This is a base file name. File is located in "{{ prometheus_config_dir }}/file_sd/<<BASENAME>>.yml"
    - targets:              #
        - localhost:9100    # All this is a targets section in file_sd format
      labels:               #
        env: test           #

Such config will result in creating one file named node.yml in {{ prometheus_config_dir }}/file_sd directory.

Next this file needs to be loaded into scrape config. Here is modified version of our default prometheus_scrape_configs:

prometheus_scrape_configs:
  - job_name: "prometheus"    # Custom scrape job, here using `static_config`
    metrics_path: "/metrics"
    static_configs:
      - targets:
          - "localhost:9090"
  - job_name: "example-node-file-servicediscovery"
    file_sd_configs:
      - files:
          - "{{ prometheus_config_dir }}/file_sd/node.yml" # This line loads file created from `prometheus_targets`

Example

Playbook

---
- hosts: all
  roles:
  - cloudalchemy.prometheus
  vars:
    prometheus_targets:
      node:
      - targets:
        - localhost:9100
        - demo.cloudalchemy.org:9100
        labels:
          env: demosite

Demo site

Prometheus organization provide a demo site for full monitoring solution based on prometheus and grafana. Repository with code and links to running instances is available on github.

Defining alerting rules files

Alerting rules are defined in prometheus_alert_rules variable. Format is almost identical to one defined in Prometheus 2.0 documentation. Due to similarities in templating engines, every templates should be wrapped in {% raw %} and {% endraw %} statements. Example is provided in defaults/main.yml file.

Local Testing

The preferred way of locally testing the role is to use Docker and molecule (v2.x). You will have to install Docker on your system. See "Get started" for a Docker package suitable to for your system. We are using tox to simplify process of testing on multiple ansible versions. To install tox execute:

pip3 install tox

To run tests on all ansible versions (WARNING: this can take some time)

tox

To run a custom molecule command on custom environment with only default test scenario:

tox -e py35-ansible28 -- molecule test -s default

For more information about molecule go to their docs.

If you would like to run tests on remote docker host just specify DOCKER_HOST variable before running tox tests.

CircleCI

Combining molecule and CircleCI allows us to test how new PRs will behave when used with multiple ansible versions and multiple operating systems. This also allows use to create test scenarios for different role configurations. As a result we have a quite large test matrix which will take more time than local testing, so please be patient.

Contributing

See contributor guideline.

Troubleshooting

See troubleshooting.

License

This project is licensed under MIT License. See LICENSE for more details.