Add Spec.MindReadySeconds to allow setting a non-default value for Mi…

…nReadySeconds in StatefulSets. Set the default MinReadySeconds to 5 in StatefulSets to prevent sudden double restarts from statefulset controller.

CHANGELOG.md

@@ -11,6 +11,7 @@ Changelog for Cass Operator, new PRs should update the `main / unreleased` secti
 
 ## unreleased
 
+* [ENHANCEMENT] [#648](https://github.com/k8ssandra/cass-operator/issues/648) Add a default (5 seconds) MinReadySeconds to the StatefulSets and make that value configurable in the Spec. Also, do not allow upgrade of StatefulSet even if it's out of date, if previous update hasn't yet finished.
 * [BUGFIX] [#652](https://github.com/k8ssandra/cass-operator/issues/652) Update nodeStatuses info when a pod is recreated
 
 ## v1.20.0

apis/cassandra/v1beta1/cassandradatacenter_types.go

@@ -258,6 +258,10 @@ type CassandraDatacenterSpec struct {
 	// Use cautiously.
 	// +optional
 	DatacenterName string `json:"datacenterName,omitempty"`
+
+	// MinReadySeconds sets the minimum number of seconds for which a newly created pod should be ready without any of its containers crashing, for it to be considered available. Defaults to 5 seconds and is set in the StatefulSet spec.
+	// Setting to 0 might cause multiple Cassandra pods to restart at the same time despite PodDisruptionBudget settings.
+	MinReadySeconds *int32 `json:"minReadySeconds,omitempty"`
 }
 
 type NetworkingConfig struct {

config/crd/bases/cassandra.datastax.com_cassandradatacenters.yaml

@@ -348,6 +348,12 @@ spec:
                     - serverSecretName
                     type: object
                 type: object
+              minReadySeconds:
+                description: |-
+                  MinReadySeconds sets the minimum number of seconds for which a newly created pod should be ready without any of its containers crashing, for it to be considered available. Defaults to 5 seconds and is set in the StatefulSet spec.
+                  Setting to 0 might cause multiple Cassandra pods to restart at the same time despite PodDisruptionBudget settings.
+                format: int32
+                type: integer
               networking:
                 properties:
                   hostNetwork:

pkg/reconciliation/construct_statefulset.go

@@ -145,13 +145,18 @@ func newStatefulSetForCassandraDatacenter(
 			PodManagementPolicy:  appsv1.ParallelPodManagement,
 			Template:             *template,
 			VolumeClaimTemplates: volumeClaimTemplates,
+			MinReadySeconds:      5,
 		},
 	}
 
 	if sts != nil && sts.Spec.ServiceName != "" && sts.Spec.ServiceName != result.Spec.ServiceName {
 		result.Spec.ServiceName = sts.Spec.ServiceName
 	}
 
+	if dc.Spec.MinReadySeconds != nil {
+		result.Spec.MinReadySeconds = *dc.Spec.MinReadySeconds
+	}
+
 	// add a hash here to facilitate checking if updates are needed
 	utils.AddHashAnnotation(result)