Allow parallel restart of all already bootstrapped nodes

CHANGELOG.md

@@ -12,6 +12,7 @@ Changelog for Cass Operator, new PRs should update the `main / unreleased` secti
 ## unreleased
 
 * [ENHANCEMENT] [#648](https://github.com/k8ssandra/cass-operator/issues/648) Make MinReadySeconds configurable value in the Spec.
+* [FEATURE] [#646](https://github.com/k8ssandra/cass-operator/issues/646) Allow starting multiple parallel pods if they have already previously bootstrapped and not planned for replacement. Set annotation ``cassandra.datastax.com/allow-parallel-starts: true`` to enable this feature.
 
 ## v1.21.1
 

apis/cassandra/v1beta1/cassandradatacenter_types.go

@@ -68,6 +68,9 @@ const (
 	// UpdateAllowedAnnotation marks the Datacenter to allow upgrades to StatefulSets Spec even if CassandraDatacenter object was not modified. Allowed values are "once" and "always"
 	UpdateAllowedAnnotation = "cassandra.datastax.com/autoupdate-spec"
 
+	// AllowParallelStartsAnnotations allows the operator to start multiple server nodes at the same time if they have already bootstrapped.
+	AllowParallelStartsAnnotations = "cassandra.datastax.com/allow-parallel-starts"
+
 	AllowUpdateAlways AllowUpdateType = "always"
 	AllowUpdateOnce   AllowUpdateType = "once"
 

pkg/reconciliation/reconcile_racks.go

@@ -605,6 +605,19 @@ func (rc *ReconciliationContext) CheckPodsReady(endpointData httphelper.CassMeta
 		return result.Error(err)
 	}
 
+	// step 0 - fastpath
+	if metav1.HasAnnotation(rc.Datacenter.ObjectMeta, api.AllowParallelStartsAnnotations) && rc.Datacenter.Annotations[api.AllowParallelStartsAnnotations] == "true" {
+		notReadyPods, err := rc.startBootstrappedNodes(endpointData)
+		if err != nil {
+			return result.Error(err)
+		}
+
+		// Technically this is checked in the next part, but there could be cache issues
+		if notReadyPods {
+			return result.RequeueSoon(2)
+		}
+	}
+
 	// step 1 - see if any nodes are already coming up
 
 	nodeIsStarting, _, err := rc.findStartingNodes()
@@ -928,13 +941,16 @@ func (rc *ReconciliationContext) CreateUsers() result.ReconcileResult {
 	return result.Continue()
 }
 
-func findHostIdForIpFromEndpointsData(endpointsData []httphelper.EndpointState, ip string) string {
+func findHostIdForIpFromEndpointsData(endpointsData []httphelper.EndpointState, ip string) (bool, string) {
 	for _, data := range endpointsData {
 		if net.ParseIP(data.GetRpcAddress()).Equal(net.ParseIP(ip)) {
-			return data.HostID
+			if data.HasStatus(httphelper.StatusNormal) {
+				return true, data.HostID
+			}
+			return false, data.HostID
 		}
 	}
-	return ""
+	return false, ""
 }
 
 func getRpcAddress(dc *api.CassandraDatacenter, pod *corev1.Pod) string {
@@ -984,11 +1000,14 @@ func (rc *ReconciliationContext) UpdateCassandraNodeStatus(force bool) error {
 			if force || nodeStatus.HostID == "" {
 				endpointsResponse, err := rc.NodeMgmtClient.CallMetadataEndpointsEndpoint(pod)
 				if err == nil {
-					nodeStatus.HostID = findHostIdForIpFromEndpointsData(
+					ready, hostId := findHostIdForIpFromEndpointsData(
 						endpointsResponse.Entity, ip)
 					if nodeStatus.HostID == "" {
 						logger.Info("Failed to find host ID", "pod", pod.Name)
 					}
+					if ready {
+						nodeStatus.HostID = hostId
+					}
 				}
 			}
 		}
@@ -1753,6 +1772,29 @@ func (rc *ReconciliationContext) findStartingNodes() (bool, bool, error) {
 	return false, false, nil
 }
 
+func (rc *ReconciliationContext) startBootstrappedNodes(endpointData httphelper.CassMetadataEndpoints) (bool, error) {
+	rc.ReqLogger.Info("reconcile_racks::startBootstrappedNodes")
+
+	startingNodes := false
+
+	for _, pod := range rc.dcPods {
+		if _, ok := rc.Datacenter.Status.NodeStatuses[pod.Name]; ok {
+			// Verify pod is not going to be replaced
+			if utils.IndexOfString(rc.Datacenter.Status.NodeReplacements, pod.Name) > -1 {
+				continue
+			}
+			notReady, err := rc.startNode(pod, false, endpointData)
+			if err != nil {
+				return startingNodes, err
+			}
+
+			startingNodes = startingNodes || notReady
+		}
+	}
+
+	return startingNodes, nil
+}
+
 func (rc *ReconciliationContext) findStartedNotReadyNodes() (bool, error) {
 	rc.ReqLogger.Info("reconcile_racks::findStartedNotReadyNodes")
 
@@ -1922,8 +1964,7 @@ func (rc *ReconciliationContext) startNode(pod *corev1.Pod, labelSeedBeforeStart
 					"Labeled pod a seed node %s", pod.Name)
 			}
 
-			err := rc.startCassandra(endpointData, pod)
-			if err != nil {
+			if err := rc.startCassandra(endpointData, pod); err != nil {
 				return true, err
 			}
 		}