Setting podManagementPolicy in Juju k8s StatefulSet

[Dominik Fleischmann]

By default when deploying a Juju k8s charm with storage a StatefulSet is created where the Pods will be created if there are several units.

In a default StatefulSet the podManagementPolicy is set to OrderedReady so each pod will be created after the previous one is ready.

In Juju on the other hand this value has been changed to Parallel so all Pods are initiated at the same time.

This is causing us issues in some applications like a Mariadb Cluster where the Primary Node has to be created before the Secondary ones.

Adding an option, to make this value configurable in the Charms would solve these issues.

[Richard Harding (rharding)]

Tossing over to Christian to take a look at what we might need to do here. Thanks for the bug report.

[Yang Kelvin Liu (kelvin.liu)]

https://github.com/juju/juju/pull/10642 will be released in 2.7 to introduce this feature.

[Ian Booth (wallyworld)]

You can update charms to use the new pod spec v2 and set the scale policy. There will be a discourse post soon to explain the details of how pod spec v2 works. The relevant change here is a new "scale policy" attribute under service.

# podspec.yaml
version: 2
service:
  scalePolicy: serial

The value can be "parallel" (default) or "serial"