Pull logs and outputs off cStor components and storage nodes

[Niladri Halder]

This is to enable the support team to gather logs.

Use-case write-up:
Expectation: User is able to pull container logs off of cStor-pool containers (old and new schema) and cStor target pod container based on the cStor volume consumed.

Observation: User is able to identify which pod is failing due to an RO volume, or other volume errors. He is also able to get a PVC name. It falls upon the support engineer to identify the target pod (from the PV name), pull 'get cstorvolume', 'get cvr', 'get bd', 'get bdc' outputs. And eventually gather the logs for the target pod and the cstor pool pods. Also we'd sometimes have pull logs off exited containers to troubleshoot.

How do users access the logs?
They access the logs via the apiserver....
E.g.
kubectl -n openebs logs -c cstor-pool
kubectl -n openebs logs -c cstor-pool-mgmt
kubectl -n openebs logs -c cstor-istgt

Do they login to nodes and get them?
No, often they won't because we mostly require container logs (commands above). But we often ask for lsblk ... for this they'd most certainly log in to the nodes and get it.

Do they use some tools to get the logs?
No, just kubectl logs.