Refactor adding multisite metrics

Author: András Váczi

patroni/api.py

@@ -671,11 +671,7 @@ def do_GET_metrics(self) -> None:
         metrics.append("# TYPE patroni_is_paused gauge")
         metrics.append("patroni_is_paused{0} {1}".format(labels, int(postgres.get('pause', 0))))
 
-        if patroni.multisite.is_active:
-            metrics.append("# HELP patroni_multisite_switches Number of times multisite leader has been switched")
-            metrics.append("# TYPE patroni_multisite_switches counter")
-            metrics.append("patroni_multisite_switches{0} {1}"
-                           .format(labels, patroni.multisite.site_switches))
+        patroni.multisite.append_metrics(metrics, labels)
 
         self.write_response(200, '\n'.join(metrics) + '\n', content_type='text/plain')
 
@@ -1199,7 +1195,7 @@ def do_POST_multisite_switchover(self):
         if not request:
             return
         if not self.server.patroni.multisite.is_active:
-            return self._write_response(400, 'Cluster is not in multisite mode')
+            return self.write_response(400, 'Cluster is not in multisite mode')
 
         scheduled_at = request.get('scheduled_at')
         target_site = request.get('target_site')

patroni/multisite.py

@@ -59,6 +59,9 @@ def should_failover(self):
     def on_shutdown(self, checkpoint_location):
         pass
 
+    def append_metrics(self, metrics, labels):
+        pass
+
 
 class SingleSiteController(AbstractSiteController):
     """Do nothing controller for single site operation."""
@@ -372,6 +375,11 @@ def shutdown(self):
         self._heartbeat.set()
         self.join()
 
+    def append_metrics(self, metrics, labels):
+        metrics.append("# HELP patroni_multisite_switches Number of times multisite leader has been switched")
+        metrics.append("# TYPE patroni_multisite_switches counter")
+        metrics.append("patroni_multisite_switches{0} {1}".format(labels, self.site_switches))
+
 
 class KubernetesStateManagement:
     def __init__(self, crd_name, crd_uid, reporter, crd_api):