Recently I’ve encountered an issue while deploying PMM on AWS ECS, however this issue will also apply to Docker deployments.
As per Percona documentation https://www.percona.com/doc/percona-monitoring-and-management/deploy/server/docker.setting-up.html in order to make configuration persistent fallowing path have to be persistent:
-v /var/lib/grafana \
Looks that currently QAN agent configuration is stored in:
Due to that in order to make sure that all agents are up and running after container crash etc. those paths currently have to be set as permanent as well.
In case that those paths are not persistent, QAN agent is not collecting Query stats from PS resulting with only partial startup of PMM in Docker Container after “crash” etc.
I think that it should be updated in documentation, and/or qan-agent paths modified.