Mattermost-server: Implement Affinity for Mattermost operator

[jwilander]

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Notes: Jira ticket

The Mattermost Operator is a Kubernetes operator that manages the lifecycle of a Mattermost installation.

Currently we have Affinity as a field in the type definition for a ClusterInstallation, however, this is not implemented to set mattermost to use specific nodes.

See the field here https://github.com/mattermost/mattermost-operator/blob/master/pkg/apis/mattermost/v1alpha1/clusterinstallation_types.go#L49

For this ticket implement node affinity using the existing field.

Read https://kubernetes.io/docs/concepts/configuration/assign-pod-node/#affinity-and-anti-affinity for more information on node affinity.

[jesperhansen17]

Can I look at this one?

[jwilander]

That'd be great @jesperhansen17 !

[ankitrgadiya]

@jesperhansen17 Are you still working on it? I'd like to pick it too.

[jesperhansen17]

Yes @ankitrgadiya, I'm still working on this. Will let you know otherwise.

[jesperhansen17]

@ankitrgadiya, go ahead and do this one. Realise I need to get more experience on Kubernetes.

[ankitrgadiya]

@jesperhansen17 Sure.