[RFE] Add new `omc etcd` subcommand for the etcd object count in newer must-gathers

[oarribas]

In newer must-gather versions (4.17.5+ and 4.16.27+ for now), there is a new file in the etcd_info subdirectory, that includes the etcd object count (check RFE-5765 [1] and the PR [2] for additional information).

The file is a key-value json with object_kind: number_of_objects, like:

$ jq . etcd_info/object_count.json
{
  "events": "1242",
  "secrets": "635",
  "configmaps": "525",
[...]

This RFE is to include a new omc etcd objects sub-command (or different name) to show that information if the above file exists,as in many cases it could help identifying an issue due to big amount of any object. The default command could show only the top-10 object count.

[1] https://issues.redhat.com/browse/RFE-5765
[2] openshift/must-gather#435

[oarribas]

With openshift/must-gather#542 and the backport for different releases, the content of file etcd_info/object_count.json will include also the size of the objects in the etcd Data Base. For checking it manually, the following command can be used:

$ jq -r '["COUNT", "NAME", "SIZE"], ( .etcd_resources[] | [ .[] ]) | @tsv' must-gather/etcd_info/object_count.json | column -t

COUNT  NAME                                                SIZE
512    /kubernetes.io/configmaps                           8.8M
6801   /kubernetes.io/events                               5.8M
636    /kubernetes.io/secrets                              4.5M
138    /kubernetes.io/apiextensions.k8s.io                 4.0M

It will be useful to have an omc etcd subcommand to show that info, something like omc etcd objects-size or similar.