Adding ImagePullPolicy config option to OSM Charms

Change-Id: I04ad8444088e8a360755dc4e22b7ea53942682b2
Signed-off-by: sousaedu <eduardo.sousa@canonical.com>
diff --git a/installers/charm/keystone/config.yaml b/installers/charm/keystone/config.yaml
index 9a7acd5..945ea48 100644
--- a/installers/charm/keystone/config.yaml
+++ b/installers/charm/keystone/config.yaml
@@ -42,6 +42,12 @@
     type: string
     description: Ingress URL
     default: ""
+  image_pull_policy:
+    type: string
+    description: |
+      ImagePullPolicy configuration for the pod.
+      Possible values: always, ifnotpresent, never
+    default: always
   region_id:
     type: string
     description: Region ID to be created when starting the service
diff --git a/installers/charm/keystone/src/charm.py b/installers/charm/keystone/src/charm.py
index 1dd0ba5..4e04e88 100755
--- a/installers/charm/keystone/src/charm.py
+++ b/installers/charm/keystone/src/charm.py
@@ -84,6 +84,7 @@
     mysql_host: Optional[str]
     mysql_port: Optional[int]
     mysql_root_password: Optional[str]
+    image_pull_policy: Optional[str]
 
     @validator("max_file_size")
     def validate_max_file_size(cls, v):
@@ -111,6 +112,18 @@
             raise ValueError("Mysql port out of range")
         return v
 
+    @validator("image_pull_policy")
+    def validate_image_pull_policy(cls, v):
+        values = {
+            "always": "Always",
+            "ifnotpresent": "IfNotPresent",
+            "never": "Never",
+        }
+        v = v.lower()
+        if v not in values.keys():
+            raise ValueError("value must be always, ifnotpresent or never")
+        return values[v]
+
 
 class ConfigLdapModel(ModelValidator):
     ldap_enabled: bool
@@ -261,7 +274,9 @@
         pod_spec_builder = PodSpecV3Builder()
 
         # Build Container
-        container_builder = ContainerV3Builder(self.app.name, image_info)
+        container_builder = ContainerV3Builder(
+            self.app.name, image_info, config.image_pull_policy
+        )
         container_builder.add_port(name=self.app.name, port=PORT)
 
         # Build files