Enable multiple arbitrary config-flags

The config flags are a comma-seperated list of keys and values.
This enables an operator to pass arbitrary configuration into
the masakari-monitors configuration.

Closes-Bug: #1941650
Change-Id: I3571bf7dfcb092ce5d04f439806e9a25465e16c5

src/config.yaml

@@ -3,3 +3,11 @@ options:
     type: string
     default: RegionOne
     description: OpenStack Region
+  config-flags:
+    type: string
+    default:
+    description: |
+      Setting multiple arbitrary config variables and these
+      will be converted into dictionary and masakarimonitors.conf will be populated
+      accordingly. This will enable an operator to have the flexibility for having
+      multiple arbitrary config flags.

src/lib/charm/openstack/masakari_monitors.py

@@ -59,3 +59,9 @@ class MasakariMonitorsCharm(charms_openstack.charm.OpenStackCharm):
 
     def install(self):
         super(MasakariMonitorsCharm, self).install()
+
+    # convert comma seprated list of config_flags into a dictionary
+    @charms_openstack.adapters.config_property
+    def user_config_flags(self):
+        return dict(map(lambda x: x.split('='),
+                        self.config.get('config-flags').split(', ')))

src/templates/masakarimonitors.conf

@@ -19,6 +19,9 @@ password = {{ identity_credentials.credentials_password }}
 project_domain_id = {{ identity_credentials.credentials_project_domain_id }}
 user_domain_id = {{ identity_credentials.credentials_user_domain_id }}
 region = {{ options.region }}
+{% for key, value in options.config_flags.items() -%}
+{{ key }} = {{ value }}
+{% endfor -%}
 [callback]
 [cors]
 [healthcheck]

unit_tests/test_lib_charm_openstack_masakari_monitors.py

@@ -51,3 +51,11 @@ class TestMasakariMonitorsCharm(Helper):
         c.request_credentials()
         keystone_relation.request_credentials.assert_called_once_with(
             'masakari-monitors', project='services')
+
+    def test_user_config_flags(self):
+        charm = self.\
+            _patch_config_and_charm({'config-flags': 'k1=v1, k2=v2'})
+        config = charm.user_config_flags()
+        # Add check here that configuration is as expected.
+        self.assertEqual(config.get('k1'), "v1")
+        self.assertEqual(config.get('k2'), "v2")