Are there any metrics I can get from the API server? or any docker image I can point to the backend and get some metrics? Most important is the see how many tasks running in real-time (like we can see on the worker's page) and also check how much time each task is running (also can be found on the worker's page)
If it does not exist, do they have an API for getting all this information?
Disclaimer: I'm a member of the ClearML team
Currently, The open-source ClearML Server does not have such a feature (PRs will be welcome, of course).
For an API, see the Server API documentation, specifically the Task Management API.