Setup Rook/Ceph

[ranguard]

Following on from our discussions

We do want to implement Rook in DigitalOcean

Aims

• Disk space claims one of two types: volatile (not retained), durable (retained and maybe backed up one day).

Useful references:

• https://www.jackpearce.co.uk/running-rook-ceph-on-digitalocean-doks-managed-kubernetes/
• https://github.com/jkpedo/rook/tree/doks (note specific branch)
• https://github.com/jkpedo/rook/blob/doks/deploy/examples/cluster-on-pvc-doks.yaml