fixes race condition when deleting alertmanager, prometheus and thanosruler instances

pkg/alertmanager/operator.go

@@ -640,6 +640,11 @@ func (c *Operator) sync(ctx context.Context, key string) error {
 		return fmt.Errorf("failed to set Alertmanager type information: %w", err)
 	}
 
+	// Check if the Alertmanager instance is marked for deletion.
+	if c.rr.DeletionInProgress(am) {
+		return nil
+	}
+
 	if am.Spec.Paused {
 		return nil
 	}

pkg/prometheus/agent/operator.go

@@ -514,6 +514,12 @@ func (c *Operator) sync(ctx context.Context, key string) error {
 	}
 
 	logger := log.With(c.logger, "key", key)
+
+	// Check if the Agent instance is marked for deletion.
+	if c.rr.DeletionInProgress(p) {
+		return nil
+	}
+
 	if p.Spec.Paused {
 		level.Info(logger).Log("msg", "the resource is paused, not reconciling")
 		return nil

pkg/prometheus/server/operator.go

@@ -1166,6 +1166,11 @@ func (c *Operator) sync(ctx context.Context, key string) error {
 	logger := log.With(c.logger, "key", key)
 	logDeprecatedFields(logger, p)
 
+	// Check if the Prometheus instance is marked for deletion.
+	if c.rr.DeletionInProgress(p) {
+		return nil
+	}
+
 	if err := operator.CheckStorageClass(ctx, c.canReadStorageClass, c.kclient, p.Spec.Storage); err != nil {
 		return err
 	}

pkg/thanos/operator.go

@@ -533,6 +533,11 @@ func (o *Operator) sync(ctx context.Context, key string) error {
 		return errors.Wrap(err, "failed to set ThanosRuler type information")
 	}
 
+	// Check if the Thanos instance is marked for deletion.
+	if o.rr.DeletionInProgress(tr) {
+		return nil
+	}
+
 	if tr.Spec.Paused {
 		return nil
 	}