fix: Set serviceName on StatefulSets
#152
Conversation
In order for pods in a STS to "know" their FQDN (instead of just their
hostname), the `spec.serviceName` attribute must be set. This will
configure their FQDN to be
`${metadata.name}.${spec.serviceName}.${metadata.namespace}.svc.cluster.local`
One example where this is needed is when deploying a MongoDB Replicaset;
Pods can only communicate with each other via the FQDN, not their
hostnames alone; but they won't recognize "themselves" in the member
list when they aren't aware of their own FQDN.
Signed-off-by: Manuel Hutter <[email protected]>
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LGTM, thank you! |
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This change is breaking existing setups, and I think it should be reverted. This also needs a migration path. The reason is that this tries to change the "serviceName" field of existing statefulSets, but that's not allowed: "updates to statefulset spec for fields other than 'replicas', 'ordinals', 'template', 'updateStrategy', 'persistentVolumeClaimRetentionPolicy' and 'minReadySeconds' are forbidden" I don't have a good idea yet how to fix this... |
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One way to fix this which worked for me: Delete the StatefulSet while keeping the PV, and let k8ify re-create the statefulSet. |
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The proper way to fix this problem is to use
Note --cascade=orphan which will ensure that the pods associated with the StatefulSet that you’re deleting continue running. Redeploy using k8ify immediately after, otherwise you might get issues later. Since this problem hasn't been addressed for two weeks now it probably doesn't make much sense anymore to revert the change. Instead unfortunately users will have to modify their StatefulSets using the mentioned procedure (which would have been necesssary anyway, but it should have been documented better). |
In order for pods in a STS to "know" their FQDN (instead of just their hostname), the
spec.serviceNameattribute must be set. This will configure their FQDN to be${metadata.name}.${spec.serviceName}.${metadata.namespace}.svc.cluster.localOne example where this is needed is when deploying a MongoDB Replicaset; Pods can only communicate with each other via the FQDN, not their hostnames alone; but they won't recognize "themselves" in the member list when they aren't aware of their own FQDN.
Checklist
bug,enhancement,documentation,change,breaking,dependencyas they show up in the changelog