Improve placement / constraints modeling for k8s charms: tolerances, and affinity / anti-affinity

[Cory Johns]

In addition to nodeSelectors, Kubernetes supports tolerations and affinity / anti-affinity to influence scheduling pods to nodes. Tolerations in particular are important for setups where certain nodes should be reserved for system-level services and thus have taints on them to prevent scheduling normal pods, which can be selectively overridden by tolerations on the pod spec. We've already had at least one request to adjust tolerations for a cdk-addon which is currently being converted to a K8s charm.

[Cory Johns (johnsca)]

Also, in line with https://bugs.launchpad.net/juju/+bug/1893123 it would be important for the charm to be able to specify default values for the ones modeled by placement.

[Pen Gale (pengale)]

This did not make the roadmap. Removing from milestone and marking as medium.

[Canonical Juju QA Bot (juju-qa-bot)]

This Medium-priority bug has not been updated in 60 days, so we're marking it Low importance. If you believe this is incorrect, please update the importance.