Improve docs around storageClassName

Author: benbz

charts/matrix-stack/source/common/sub_schema_values.yaml.j2

@@ -194,9 +194,10 @@ imagePullSecrets: []
   size: 10Gi
 
   ## The StorageClass to be used by the constructed PersistentVolumeClaim.
-  ## Will use the cluster default if not provided
+  ## Will use the cluster default if not provided.
+  ## If changed after initial usage the PersistentVolumeClaim could be recreated causing data-loss.
   ## Ignored if existingClaim is provided
-  # storageClass:
+  # storageClassName:
 
   ## Whether to instruct Helm to keep or delete the constructed PersistentVolumeClaim when uninstalling the chart
   ## Ignored if existingClaim is provided

charts/matrix-stack/values.yaml

@@ -2083,9 +2083,10 @@ postgres:
     size: 10Gi
 
     ## The StorageClass to be used by the constructed PersistentVolumeClaim.
-    ## Will use the cluster default if not provided
+    ## Will use the cluster default if not provided.
+    ## If changed after initial usage the PersistentVolumeClaim could be recreated causing data-loss.
     ## Ignored if existingClaim is provided
-    # storageClass:
+    # storageClassName:
 
     ## Whether to instruct Helm to keep or delete the constructed PersistentVolumeClaim when uninstalling the chart
     ## Ignored if existingClaim is provided
@@ -2363,9 +2364,10 @@ synapse:
       size: 10Gi
 
       ## The StorageClass to be used by the constructed PersistentVolumeClaim.
-      ## Will use the cluster default if not provided
+      ## Will use the cluster default if not provided.
+      ## If changed after initial usage the PersistentVolumeClaim could be recreated causing data-loss.
       ## Ignored if existingClaim is provided
-      # storageClass:
+      # storageClassName:
 
       ## Whether to instruct Helm to keep or delete the constructed PersistentVolumeClaim when uninstalling the chart
       ## Ignored if existingClaim is provided

newsfragments/583.fixed.md

@@ -0,0 +1,13 @@
+Fix Postgres and Synapse Media `storageClassName` configuration not being respected.
+
+**Warning** Previously `synapse.media.storage.storageClass` and `postgres.storage.storageClass`
+were in the values file and associated schema. These values were accidentally silently ignored
+and all chart-managed `PersistentVolumeClaims` were constructed without `spec.storageClassName`
+set, using the cluster default `StorageClass`.
+
+The values file and associated schema have been updated so that the values are now
+`synapse.media.storage.storageClassName` and `postgres.storage.storageClassName`. The previous
+values are disallowed by the schema. Setting these values after the initial install could 
+cause the `PersistentVolumeClaims` to be recreated, with associated data-loss. Only set
+`synapse.media.storage.storageClassName` or `postgres.storage.storageClassName` on initial
+installation.