Juju does not add pod affinity to pods when specifying tags in constraints

[Stone Preston]

According to this post: https://discourse.charmhub.io/t/pod-priority-and-affinity-in-juju-charms/4091/6, juju should add node affinities to pods when specifying tags in the constraints in the form of node.key=value. This does not happen:

$ juju deploy hello-kubecon --constraints "tags=node.some-label=some-value"`

$ kubectl get -o json statefulset.apps/hello-kubecon -n repro-model | jq .spec.template.spec.affinity

The above was tested on juju 2.9.28 and k8s 1.23 and 1.24 clusters.

The spec template does not have any affinity. I really need to be able to deploy a charm to a specific k8s node, either via node affinity or node selector. Is there another way for juju to accomplish this?

[Stone Preston (stonepreston)]

A workaround for this issue is to patch the statefulset with a node-selector (or nodeAffinity depending on how complex the rules required are for scheduling).

$ kubectl patch statefulset hello-kubecon -p '{"spec": {"template": {"spec": {"nodeSelector": {"some-label": "some-value"}}}}}' -n repro-model

[Ian Booth (wallyworld)]

I think the affinity constraints only work with the original podspec charms and the implementation needs to be ported across to sidecar charms.

[Ian Booth (wallyworld)]

Just a follow up on this, support for affinity with sidecar charms landed a while back.
It's in juju 3.3 and later.