To survive PMM upgrades where we replace Prometheus configuration file, but keep Consul data volume.
Consul KV data should be visible in the web interface on http(s)://hostname/consul
How to test:
- Make a clean installation.
- Copy prometheus.yml file.
- Add several external exporters.
- Stop Prometheus, pmm-managed.
- Restore prometheus.yml to the original form
- Start Prometheus, pmm-managed.
- prometheus.yml should include external exporters (they are added by pmm-managed), Prometheus configuration should be reloaded (that is visible in logs).
Nothing to document, that's an implementation detail.