All variables which can be overridden are stored in [defaults/main.yml](defaults/main.yml) file as well as in [meta/argument_specs.yml](meta/argument_specs.yml).
Please refer to the [collection docs](https://prometheus-community.github.io/ansible/branch/main/prometheus_role.html) for description and default values of the variables.
### 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](https://prometheus.io/docs/prometheus/latest/configuration/configuration/#file_sd_config) and they need to be read in `prometheus_scrape_configs`.
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](https://prometheus.io/docs/prometheus/latest/configuration/configuration/#scrape_config) are used.
Meanwhile `prometheus_targets` is our way of adopting [prometheus scrape type `file_sd`](https://prometheus.io/docs/prometheus/latest/configuration/configuration/#file_sd_config). 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`
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](https://github.com/prometheus/demo-site).
### 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](https://prometheus.io/docs/prometheus/latest/configuration/template_examples/).
Due to similarities in templating engines, every templates should be wrapped in `{% raw %}` and `{% endraw %}` statements. Example is provided in [defaults/main.yml](defaults/main.yml) file.
## Local Testing
The preferred way of locally testing the role is to use Docker and [molecule](https://github.com/metacloud/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:
```sh
pip3 install tox
```
To run tests on all ansible versions (WARNING: this can take some time)
```sh
tox
```
To run a custom molecule command on custom environment with only default test scenario:
```sh
tox -e py35-ansible28 -- molecule test -s default
```
For more information about molecule go to their [docs](http://molecule.readthedocs.io/en/latest/).
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](CONTRIBUTING.md).
## Troubleshooting
See [troubleshooting](TROUBLESHOOTING.md).
## License
This project is licensed under MIT License. See [LICENSE](/LICENSE) for more details.
