Merge pull request #59731 from achew22/patch-1

Automatic merge from submit-queue (batch tested with PRs 63049, 59731). If you want to cherry-pick this change to another branch, please follow the instructions <a href="https://github.com/kubernetes/community/blob/master/contributors/devel/cherry-picks.md">here</a>.

Add instructions on how to debug a crashed pod

When I was using `kubeadm init`, I ran into an issue where I had passed an
invalid flag through the kubeadm config file. The flag was being passed into
apiserver and preventing it from launching with a "unknown flag" error.

The flag in question is (other flags elided for clarity):

```
admission-control: ...,GenericAdmissionWebhook,...
```

Since this prevented the apiserver from coming up, the setup timed out
and gave me the error message I just modified.

It would be better if the config was vetted more thoroughly, but I think
documenting the backup strategy for viewing logs in case of failure is
also valuable.



**What this PR does / why we need it**:
This PR extends an error message in kubeadm to make it clear a potential step forward for new cluster users.

**Which issue(s) this PR fixes** *(optional, in `fixes #<issue number>(, fixes #<issue_number>, ...)` format, will close the issue(s) when PR gets merged)*:
Fixes #59731 

**Special notes for your reviewer**:

**Release note**:
```release-note
NONE
```

cmd/kubeadm/app/cmd/init.go

@@ -103,6 +103,14 @@ var (
 		If you are on a systemd-powered system, you can try to troubleshoot the error with the following commands:
 			- 'systemctl status kubelet'
 			- 'journalctl -xeu kubelet'
+		
+		Additionally a control plane component may not have come up in docker. If that's the case, you can enumerate 
+		all docker containers that have been started (including ones that have crashed and exited) by running the
+		following commands:
+			- 'docker ps -a'
+		
+		Once you have that list, you can inspect the logs for any pod with:
+			- 'docker logs $CONTAINERID'
 		`)))
 )