controller: delete reconcile metric for orphaned PromRule in advance

CHANGELOG.md

@@ -9,6 +9,11 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [0.6.1] - 2020-09-16
 
+### Changed
+
+- Delete the reconcile time metric for orphaned `PrometheusRule` in advance,
+  regardless of the cleanup error status.
+
 ### Fixed
 
 - Use a single loop for controller worker.

internal/controller/cleanup.go

@@ -84,10 +84,10 @@ func (c *Controller) cleanUpOrphanedAbsentAlertsCluster() error {
 
 			aPR := &absentPrometheusRule{PrometheusRule: pr}
 			for n := range cleanup {
+				c.metrics.SuccessfulPrometheusRuleReconcileTime.DeleteLabelValues(namespace, n)
 				if err := c.cleanUpOrphanedAbsentAlerts(n, aPR); err != nil {
 					return err
 				}
-				c.metrics.SuccessfulPrometheusRuleReconcileTime.DeleteLabelValues(namespace, n)
 			}
 		}
 	}

internal/controller/controller.go

@@ -309,10 +309,8 @@ func (c *Controller) syncHandler(key string) error {
 		// The resource may no longer exist, in which case we clean up any
 		// orphaned absent alerts.
 		c.logger.Debug("msg", "PrometheusRule no longer exists", "key", key)
+		c.metrics.SuccessfulPrometheusRuleReconcileTime.DeleteLabelValues(namespace, name)
 		err = c.cleanUpOrphanedAbsentAlertsNamespace(name, namespace)
-		if err == nil {
-			c.metrics.SuccessfulPrometheusRuleReconcileTime.DeleteLabelValues(namespace, name)
-		}
 	default:
 		// Requeue object for later processing.
 		return err