cephadm: add a new context getter for rank

Add a new context getter function to fetch a daemon's rank and rank
generation value.

Signed-off-by: John Mulligan <jmulligan@redhat.com>

1 files changed, 18 insertions, 0 deletions

diff --git a/src/cephadm/cephadmlib/context_getters.py b/src/cephadm/cephadmlib/context_getters.py
index 0bd0c0e5e6c..7b99abeaa5f 100644
--- a/src/cephadm/cephadmlib/context_getters.py
+++ b/src/cephadm/cephadmlib/context_getters.py
@@ -136,6 +136,24 @@ def fetch_endpoints(ctx: CephadmContext) -> List[EndPoint]:
     return endpoints
 
 
+def fetch_rank_info(ctx: CephadmContext) -> Optional[Tuple[int, int]]:
+    """Return the daemon's rank and rank generation values as a tuple of ints
+    if available. Return None if rank information is not available.
+    """
+    meta = getattr(ctx, 'meta_properties', None)
+    if meta is None:
+        return None
+    # We must either return both rank *and* rank_generation together or
+    # nothing at all.
+    try:
+        rank, gen = meta['rank'], meta['rank_generation']
+    except KeyError:
+        return None
+    if rank is None or gen is None:
+        return None
+    return int(rank), int(gen)
+
+
 def get_config_and_keyring(ctx):
     # type: (CephadmContext) -> Tuple[Optional[str], Optional[str]]
     config = None