ceph: add ceph_require_min_compat_client default variable (#284)

Add two variables to the new cluster policy section of all/099-ceph.yml:

ceph_require_min_compat_client (default: mimic) — passed to
`ceph osd set-require-min-compat-client` by container-image-ceph-ansible
during the ceph-pools lifecycle step. With mimic or newer, RBD clone v2
is enabled cluster-wide: parent snapshots no longer need to be protected
for clones to reference them, which allows Glance to delete images that
have active Nova ephemeral disk clones (HTTP 409 fix). Set to '' to
skip; see operator documentation for side effects on production clusters
(client lockout, Ceph trash semantics, one-way change).

ceph_min_compat_client_order — integer ordering map for release names,
used by container-image-ceph-ansible for the idempotency check: the
minimum is only raised, never lowered. Extend when new Ceph releases
are supported.

AI-assisted: Claude Code

Signed-off-by: Roger Luethi <luethi@osism.tech>

Author: ideaship

all/099-ceph.yml

@@ -10,6 +10,34 @@ fetch_directory: /share
 generate_fsid: false
 ntp_service_enabled: false
 
+##########################
+# cluster policy
+
+# Sets the Ceph OSD map require-min-compat-client parameter.
+# With mimic or newer, RBD clone v2 is used: parent snapshots no longer need
+# to be protected, enabling Glance image deletion via trash_move() when Nova
+# ephemeral RBD clones exist. Clients older than the specified release are
+# rejected cluster-wide (hard gate, not a warning). Set to '' to skip.
+# NOTE: This is effectively one-way on a live cluster once clone v2 objects
+# exist. Do not lower this value on production clusters.
+ceph_require_min_compat_client: mimic
+
+# Release ordering used to compare Ceph release names for the idempotency
+# check. Only releases from luminous onward are relevant. If ceph_require_min_compat_client
+# names a release absent from this map, the assertion task fails with a clear
+# message. If the cluster's current value is absent, the task skips.
+# Extend this map when new Ceph releases are supported.
+ceph_min_compat_client_order:
+  luminous: 12
+  mimic: 13
+  nautilus: 14
+  octopus: 15
+  pacific: 16
+  quincy: 17
+  reef: 18
+  squid: 19
+  tentacle: 20
+
 # NOTE(berendt): We use an adapted Ceph image in which always the UID 64045 is used
 ceph_uid: 64045
 bootstrap_dirs_owner: "64045"