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).
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: