What are the best tools to monitor the overall perfromance and to set thresholds for Alerting in OpenShift Container Platform .
There are many monitoring solutions that are openshift aware, and these are different from cluster metrics (Hawkular/Heapster or Prometheus).
I've seen people going with Prometheus more often for both cluster metrics, monitoring and APM.
For alerting, Prometheus has a component 'AlertManager' that does exactly that.
We had it configured to send alerts both by email and on Slack.
It's a great and powerful framework (not solution), to be used in conjuction with dashboarding tools like Grafana.
I know Dynatrace is offering its agent 'oneagent' through the Red Hat Container Registry, but I have yet to test it.
One very promising solution is https://sysdig.com (cloud sysdig, not console sysdig, the open source tool).
Finally, OCP 3.11 ships with Prometheus and Grafana!!
While we're on the subject of OpenShift and monitoring, I'll take this opportunity to plug http://uncontained.io which has a guide that attempts to give some high level recommendations around an OpenShift monitoring solution, as well as a ton of other useful articles around cloud, devops, and containerization topics:
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