Predict the GlanceAPI volumes order

When TLS is enabled at Pod level (which is the new default introduced by
the openstack-operator), and a statefulset is created, a new revision is
rolled out because of the overrides passed by the OpenStack operator to
the service CR. In glance this introduced an additional issue: in case
of multiple APIs, an iteration is performed through the Spec instances,
and the TLS override is checked out for each endpoint. No one ensures
that the StatefulSet has the same order of the provided mountpoints, and
this might generate multiple (random) rollouts until it converges with
two subsequent revisions that keep the same order. To avoid multiple
restarts, this patch adds two utility functions to sort the Volumes and
the VolumeMounts passed to the GlanceAPI StatefulSet. By doing this we
can always predict the mount order and avoid unnecessary restarts.

Signed-off-by: Francesco Pantano <[email protected]>

pkg/glance/volumes.go

@@ -16,6 +16,7 @@ limitations under the License.
 package glance
 
 import (
+	"sort"
 	"strconv"
 
 	glancev1 "github.com/openstack-k8s-operators/glance-operator/api/v1beta1"
@@ -329,3 +330,17 @@ func GetScriptVolumeMount() []corev1.VolumeMount {
 		},
 	}
 }
+
+// SortVolumeMounts - Sorts a list (by Name) of []corev1.VolumeMount
+func SortVolumeMounts(vm []corev1.VolumeMount) {
+	sort.Slice(vm, func(i, j int) bool {
+		return vm[i].Name < vm[j].Name
+	})
+}
+
+// SortVolumes - Sorts a list (by Name) of []corev1.Volumes
+func SortVolumes(vl []corev1.Volume) {
+	sort.Slice(vl, func(i, j int) bool {
+		return vl[i].Name < vl[j].Name
+	})
+}

pkg/glanceapi/statefulset.go

@@ -147,6 +147,7 @@ func StatefulSet(
 
 	extraVolPropagation := append(glance.GlanceAPIPropagation,
 		storage.PropagationType(glance.GetGlanceAPIName(instance.Name)))
+
 	httpdVolumeMount := glance.GetHttpdVolumeMount()
 
 	// Add the CA bundle to the apiVolumes and httpdVolumeMount
@@ -179,6 +180,14 @@ func StatefulSet(
 		}
 	}
 
+	// TLS-e: we need to predict the order of both Volumes and VolumeMounts to
+	// prevent any unwanted Pod restart and StatefulSet rollout due to an
+	// update on its revision
+	for _, vmount := range [][]corev1.VolumeMount{apiVolumeMounts, httpdVolumeMount} {
+		glance.SortVolumeMounts(vmount)
+	}
+	glance.SortVolumes(apiVolumes)
+
 	stsName := instance.Name
 	// The StatefulSet name **must** match with the headless service
 	// endpoint Name (see GetHeadlessService() function under controllers/