kubeadm: perform a host name check on init / join #99194
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| if len(hc.nodeName) > 63 { | ||
| warnings = append(warnings, errors.Errorf("hostname \"%s\" should be no more than 63 characters. Change hostname or use --node-name flag to override it", hc.nodeName)) | ||
| } |
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i would like to understand more about the kubelet requirements before applying such a change.
#99156
aren't we supposed to use IsQualifiedName() instead of pining to 63?
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this is closed, until further notice.
does the kubelet actually impose validation and limitation to the hostnames the user can pass to it?
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kubelet doesn't validate it, but hostname is used in some other features like node-label selector and static-pod suffix.
If it is too long, something may not work. So I think we should add a warning here.
As this is not strictly limited, it is not an error.
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true, we are adding a warning here in kubeadm and that's fine, but i'm wondering about a few things when a Node name is too long:
- does the bootstrap finish OK (i.e. node joins the cluster)?
- can pods still schedule on this node?
i guess i can try some of these things myself..
i'm asking because maybe the kubelet should also error out on long names (separate PR).
but if some of that partially works such a change in the kubelet would need an "action required" because otherwise it will break some users.
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Add to my todo list on kubelet/sig-node
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Co-authored-by: Lubomir I. Ivanov <neolit123@gmail.com>
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/triage accepted
/approve
/priority backlog
this seems fine to me.
this check will be run on both init and join. so we should change the release note to:
kubeadm: during "init" and "join" perform preflight validation on the host / node name and throw warnings if a name is not compliant
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What type of PR is this?
/kind feature
small enhancement
What this PR does / why we need it:
#99156 (comment)
Which issue(s) this PR fixes:
Make it clear during
kubeadm join. User may encounter an issue like #99156.Longer node name may lead to label adding problem and so on.
Special notes for your reviewer:
The host name will be used as the machine name and will be used as the DNS suffix, so the host name must meet the hostname specification defined by RFC 1123. Hostname should be less than 63 characters and satisfy regular expression
^[a-z0-9]([-a-z0-9]*[a-z0-9])?(\.[a-z0-9]([-a-z0-9]*[a-z0-9])?)*$Does this PR introduce a user-facing change?
Additional documentation e.g., KEPs (Kubernetes Enhancement Proposals), usage docs, etc.: