Merge pull request #11375 from openshift-cherrypick-robot/cherry-pick…

…-10930-to-enterprise-3.9

[enterprise-3.9] BZ#1601757 - added considerations for using MySQL and PostgreSQL with azure file

install_config/persistent_storage/persistent_storage_azure_file.adoc

@@ -51,25 +51,54 @@ $ mount
 If the `dir_mode` and `file_mode` permissions are set to `0755`,  change the
 default value `0755` to `0777` or `0775`. This manual step is required because
 the default `dir_mode` and `file_mode` permissions changed from `0777` to `0755`
-in {product-title} 3.9. The following examples show configuration files with the 
+in {product-title} 3.9. The following examples show configuration files with the
 changed values.
 
+.Considerations when using MySQL and PostgresSQL with Azure file
+* The owner UID of the Azure File mounted directory is different from the UID of a container.
+* MySQL containers change the file owner permission in the mounted directory. Because of the mismatch between the owner UID and container process UID, this operation fails. Therefore to run MySQL with Azure File:
+** Specify the Azure File mounted directory UID in the `runAsUser` variable in the PV configuration file.
++
+[source, yaml]
+----
+spec:
+  containers:
+    ...
+  securityContext:
+    runAsUser: <mounted_dir_uid>
+----
+** Specify the container process UID under `mountOptions` in the PV configuration file.
++
+[source, yaml]
+----
+mountOptions:
+  - dir_mode=0700
+  - file_mode=0600
+  - uid=<conatiner_process_uid>
+  - gid=0
+----
+
+* PostgreSQL does not work with Azure file. This is because PostgreSQL requires
+hard links in the Azure File directory, and since Azure File does not support
+link:https://docs.microsoft.com/en-us/rest/api/storageservices/features-not-supported-by-the-azure-file-service[hard
+links] the pod fails to start.
+
 .PV configuration file example
 [source,yaml]
 ----
-# azf-pv.yml 
+# azf-pv.yml
 apiVersion: "v1"
 kind: "PersistentVolume"
 metadata:
-  name: "azpv" 
+  name: "azpv"
 spec:
   capacity:
-    storage: "1Gi" 
+    storage: "1Gi"
   accessModes:
     - "ReadWriteMany"
-  azureFile: 
+  azureFile:
     secretName: azure-secret
-    shareName: azftest 
+    shareName: azftest
     readOnly: false
   mountOptions:
     - dir_mode=0777