Merge pull request #300 from zalando-incubator/fix_crash_on_node_migration

Fix a crash on node migration.

pkg/cluster/pod.go

@@ -203,6 +203,15 @@ func (c *Cluster) MigrateMasterPod(podName spec.NamespacedName) error {
 		c.logger.Warningf("pod %q is not a master", podName)
 		return nil
 	}
+	// we must have a statefulset in the cluster for the migration to work
+	if c.Statefulset == nil {
+		sset, err := c.KubeClient.StatefulSets(c.Namespace).Get(c.statefulSetName(), metav1.GetOptions{})
+		if err != nil {
+			return fmt.Errorf("could not retrieve cluster statefulset: %v", err)
+		}
+		c.Statefulset = sset
+	}
+	// We may not have a cached statefulset if the initial cluster sync has aborted, revert to the spec in that case.
 	if *c.Statefulset.Spec.Replicas == 1 {
 		c.logger.Warningf("single master pod for cluster %q, migration will cause longer downtime of the master instance", c.clusterName())
 	} else {

pkg/cluster/volumes.go

@@ -103,10 +103,10 @@ func (c *Cluster) resizeVolumes(newVolume spec.Volume, resizers []volumes.Volume
 
 	for _, pv := range pvs {
 		volumeSize := quantityToGigabyte(pv.Spec.Capacity[v1.ResourceStorage])
-		if volumeSize > newSize {
-			return fmt.Errorf("cannot shrink persistent volume")
-		}
-		if volumeSize == newSize {
+		if volumeSize >= newSize {
+			if volumeSize > newSize {
+				c.logger.Warningf("cannot shrink persistent volume")
+			}
 			continue
 		}
 		for _, resizer := range resizers {