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kubernetesnodes
Abdelghani
Abdelghani

Reputation: 745

kubernetes : What are valid node fields

I would like to use podAffinity with matchFields. On the web I only found examples with field metadata.name :

- matchFields:
  - key: metadata.name
    operator: NotIn
    values:
    - worker-1

I would like to know if there are any other valid node fields I can use and how/where I can find them?

Thx in advance

Upvotes: 2

Views: 1431

Answers (1)

acid_fuji
acid_fuji

Reputation: 6853

I did some digging and I found out that Matchfields was introduced because of the issue with scheduling DaemonSets. The Controller that creates pod was depending the kubernetes.io/hostname label on a Node. This whole setup was assuming that this label is being equal to the node name which turned out wrong one becuase node name and hostname are distinct in some cases. See #61410 for more reading. This also explains why there example of using this is only related to DaemonSet in the docs.

Because of that PR #62002 was merged which added MatchFields to NodeSelectorTerm with the release note that explains that only metadata.name is being supported:

Added `MatchFields` to `NodeSelectorTerm`; in 1.11, it only support `metadata.name`.

So at the time of this writing the only supported field is metadata.name. I've check also tests code and it appears that this behavior has not changed till now.

PS. Please note that this can only be used in NodeSelector and not applicable in PodAffinity/PodAntiAffinity

Upvotes: 5

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