Got target node name of pending DaemonSet pod.

[k82cn]

Signed-off-by: Da K. Ma klaus1982.cn@gmail.com

Which issue(s) this PR fixes (optional, in fixes #<issue number>(, fixes #<issue_number>, ...) format, will close the issue(s) when PR gets merged):
part of #59194 Fixes #61050

Release note:

None

[k82cn]

/assign @janetkuo

[k82cn]

There's a race condition that: after DaemonSet controller created the pods, scheduler takes time to bind the pod to the node; if node condition was changed (e.g. label updated) during this period, a new pod was created unexpected. Refer to the following log, thousands of pods was created :(

I0320 01:25:18.592] Mar 20 01:25:18.385: INFO: 24 / 2723 pods in namespace 'kube-system' are running and ready (608 seconds elapsed)

[liggitt]

There's a race condition that: after DaemonSet controller created the pods, scheduler takes time to bind the pod to the node; if node condition was changed (e.g. label updated) during this period, a new pod was created unexpected. Refer to the following log, thousands of pods was created

Why is the daemonset creating pods that are sensitive to node label changes?

[liggitt]

it appears the daemonset depends on the value of this label matching the node name. that is not a valid assumption. see #2462 and #10612 as just a couple examples (there are many) of why this assumption is not valid.

[liggitt]

opened #61410 to track

[k82cn]

There's a race condition that: after DaemonSet controller created the pods, scheduler takes time to bind the pod to the node; if node condition was changed (e.g. label updated) during this period, a new pod was created unexpected. Refer to the following log, thousands of pods was created

Why is the daemonset creating pods that are sensitive to node label changes?

DaemonSet will create pods to the selected nodes, one of selection is node selector for node labels; so if label of node changed, DaemonSet controller should delete or create pods accordingly.

[k82cn]

There's a race condition that: after DaemonSet controller created the pods, scheduler takes time to bind the pod to the node; if node condition was changed (e.g. label updated) during this period, a new pod was created unexpected. Refer to the following log, thousands of pods was created

Why is the daemonset creating pods that are sensitive to node label changes?

DaemonSet will create pods to the selected nodes, one of selection is node selector for node labels; so if label of node changed, DaemonSet controller should delete or create pods accordingly.

[k8s-ci-robot]

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[k82cn]

/sig scheduling

[k82cn]

Thanks for liggitt@ 's comments, I'll continue this PR after #61410 merged :)

[k82cn]

Handled this in #63223 :)