Cluster (i.e. first pod) start must be managed manually

[solsson]

See https://github.com/Yolean/kubernetes-mysql-cluster#initialize-volumes-and-cluster for background.

The manual toggle of --wsrep-new-cluster is particularly bad if you suffer unplanned downtime. The cluster will not initialize, or worse you'll get replicas but they are disconnected, without manual intervention.

Someone told me there is a mechanism for running a special type of init container for the first pod in a replica set. Can't find it now.

@Jacobh2 we should look into this if you plan on running multiple clusters/instances. You might start a single instance per site, but with the possibility to scale up individual sites as load increase.