k8s: Put brokers in maintenance mode before deleting orphant pod

During rolling update, before this change, Redpanda operator was calculating
the difference between running pod specification and stateful set pod template.
If the specification did not match the pod was deleted. From release v22.1.1
operator is configuring each broker with pod lifecycle hooks. In the PreStop
hook the script will try to put broker into maintenance mode for 120 seconds
before POD is terminated. Redpanda could not finish within 120 seconds to put
one broker into maintenance mode.

This PR improves the situation by putting maintenance mode before POD is
deleted. The `EnableMaintanaceMode` function is called multiple times until
`Broker` function returns correct status. The assumption is that REST admin API
maintenance mode endpoint is idempotent.

When pod is successfully deleted statefulset would reschedule the pod with
correct pod specification.

redpanda-data#4125
redpanda-data#3023

src/go/k8s/controllers/redpanda/cluster_controller.go

@@ -551,7 +551,7 @@ func (r *ClusterReconciler) fetchAdminNodeID(ctx context.Context, rp *redpandav1
 		return -1, fmt.Errorf("creating pki: %w", err)
 	}
 
-	ordinal, err := strconv.ParseInt(getPodOrdinal(pod.Name, rp.Name), 10, 0)
+	ordinal, err := utils.GetPodOrdinal(pod.Name, rp.Name)
 	if err != nil {
 		return -1, fmt.Errorf("cluster %s: cannot convert pod name (%s) to ordinal: %w", rp.Name, pod.Name, err)
 	}
@@ -567,16 +567,6 @@ func (r *ClusterReconciler) fetchAdminNodeID(ctx context.Context, rp *redpandav1
 	return int32(cfg.NodeID), nil
 }
 
-func getPodOrdinal(podName string, clusterName string) string {
-	// Pod name needs to have at least 2 more characters
-	if len(podName) < len(clusterName)+2 {
-		return ""
-	}
-
-	// The +1 is for the separator between stateful set name and pod ordinal
-	return podName[len(clusterName)+1:]
-}
-
 func (r *ClusterReconciler) reportStatus(
 	ctx context.Context,
 	redpandaCluster *redpandav1alpha1.Cluster,

src/go/k8s/pkg/admin/admin.go

@@ -92,6 +92,7 @@ type AdminAPIClient interface {
 	GetLicenseInfo(ctx context.Context) (admin.License, error)
 
 	Brokers(ctx context.Context) ([]admin.Broker, error)
+	Broker(ctx context.Context, nodeID int) (admin.Broker, error)
 	DecommissionBroker(ctx context.Context, node int) error
 	RecommissionBroker(ctx context.Context, node int) error
 

src/go/k8s/pkg/admin/mock_admin.go

@@ -422,6 +422,26 @@ func (m *MockAdminAPI) SetBrokerStatus(
 	return fmt.Errorf("unknown broker %d", id)
 }
 
+func (m *MockAdminAPI) Broker(_ context.Context, nodeID int) (admin.Broker, error) {
+	t := true
+	return admin.Broker{
+		NodeID:           nodeID,
+		NumCores:         2,
+		MembershipStatus: "",
+		IsAlive:          &t,
+		Version:          "unversioned",
+		Maintenance: &admin.MaintenanceStatus{
+			Draining:     false,
+			Finished:     true,
+			Errors:       false,
+			Partitions:   0,
+			Eligible:     0,
+			Transferring: 0,
+			Failed:       0,
+		},
+	}, nil
+}
+
 func makeCopy(input, output interface{}) {
 	ser, err := json.Marshal(input)
 	if err != nil {

src/go/k8s/pkg/resources/statefulset_update.go

@@ -157,31 +157,13 @@ func (r *StatefulSetResource) rollingUpdate(
 		volumes[vol.Name] = new(interface{})
 	}
 
-	opts := []patch.CalculateOption{
-		patch.IgnoreStatusFields(),
-		ignoreKubernetesTokenVolumeMounts(),
-		ignoreDefaultToleration(),
-		ignoreExistingVolumes(volumes),
-	}
-
 	for i := range podList.Items {
 		pod := podList.Items[i]
 
-		patchResult, err := patch.DefaultPatchMaker.Calculate(&pod, &artificialPod, opts...)
-		if err != nil {
+		if err = r.podEviction(ctx, &pod, &artificialPod, volumes); err != nil {
 			return err
 		}
 
-		if !patchResult.IsEmpty() {
-			r.logger.Info("Changes in Pod definition other than activeDeadlineSeconds, configurator and Redpanda container name. Deleting pod",
-				"pod-name", pod.Name,
-				"patch", patchResult.Patch)
-			if err = r.Delete(ctx, &pod); err != nil {
-				return fmt.Errorf("unable to remove Redpanda pod: %w", err)
-			}
-			return &RequeueAfterError{RequeueAfter: RequeueDuration, Msg: "wait for pod restart"}
-		}
-
 		if !utils.IsPodReady(&pod) {
 			return &RequeueAfterError{
 				RequeueAfter: RequeueDuration,
@@ -207,6 +189,92 @@ func (r *StatefulSetResource) rollingUpdate(
 	return nil
 }
 
+func (r *StatefulSetResource) podEviction(ctx context.Context, pod, artificialPod *corev1.Pod, newVolumes map[string]interface{}) error {
+	opts := []patch.CalculateOption{
+		patch.IgnoreStatusFields(),
+		ignoreKubernetesTokenVolumeMounts(),
+		ignoreDefaultToleration(),
+		ignoreExistingVolumes(newVolumes),
+	}
+
+	patchResult, err := patch.DefaultPatchMaker.Calculate(pod, artificialPod, opts...)
+	if err != nil {
+		return err
+	}
+
+	if patchResult.IsEmpty() {
+		return nil
+	}
+
+	var ordinal int64
+	ordinal, err = utils.GetPodOrdinal(pod.Name, r.pandaCluster.Name)
+	if err != nil {
+		return fmt.Errorf("cluster %s: cannot convert pod name (%s) to ordinal: %w", r.pandaCluster.Name, pod.Name, err)
+	}
+
+	if *r.pandaCluster.Spec.Replicas > 1 {
+		if err = r.putInMaintenanceMode(ctx, int32(ordinal)); err != nil {
+			// As maintenance mode can not be easily watched using controller runtime the requeue error
+			// is always returned. That way a rolling update will not finish when operator waits for
+			// maintenance mode finished.
+			return &RequeueAfterError{
+				RequeueAfter: RequeueDuration,
+				Msg:          fmt.Sprintf("putting node (%s) into maintenance mode: %v", pod.Name, err),
+			}
+		}
+	}
+
+	r.logger.Info("Changes in Pod definition other than activeDeadlineSeconds, configurator and Redpanda container name. Deleting pod",
+		"pod-name", pod.Name,
+		"patch", patchResult.Patch)
+
+	if err = r.Delete(ctx, pod); err != nil {
+		return fmt.Errorf("unable to remove Redpanda pod: %w", err)
+	}
+
+	return &RequeueAfterError{RequeueAfter: RequeueDuration, Msg: "wait for pod restart"}
+}
+
+//nolint:goerr113 // out of scope for this PR
+func (r *StatefulSetResource) putInMaintenanceMode(ctx context.Context, ordinal int32) error {
+	adminAPIClient, err := r.getAdminAPIClient(ctx, ordinal)
+	if err != nil {
+		return fmt.Errorf("creating admin API client: %w", err)
+	}
+
+	nodeConf, err := adminAPIClient.GetNodeConfig(ctx)
+	if err != nil {
+		return fmt.Errorf("getting node config: %w", err)
+	}
+
+	err = adminAPIClient.EnableMaintenanceMode(ctx, nodeConf.NodeID)
+	if err != nil {
+		return fmt.Errorf("enabling maintenance mode: %w", err)
+	}
+
+	br, err := adminAPIClient.Broker(ctx, nodeConf.NodeID)
+	if err != nil {
+		return fmt.Errorf("getting broker infromations: %w", err)
+	}
+
+	if br.Maintenance == nil {
+		return fmt.Errorf("maintenance definition not returned")
+	}
+
+	switch {
+	case br.Maintenance.Draining:
+	case br.Maintenance.Errors:
+	case br.Maintenance.Failed > 0:
+		return fmt.Errorf("maintenance mode is not valid to do rolling update: %v", br.Maintenance)
+	}
+
+	if !br.Maintenance.Finished {
+		return fmt.Errorf("maintenance mode is not finished")
+	}
+
+	return nil
+}
+
 func (r *StatefulSetResource) updateStatefulSet(
 	ctx context.Context,
 	current *appsv1.StatefulSet,

src/go/k8s/pkg/utils/kubernetes.go

@@ -9,7 +9,14 @@
 
 package utils
 
-import corev1 "k8s.io/api/core/v1"
+import (
+	"fmt"
+	"strconv"
+
+	corev1 "k8s.io/api/core/v1"
+)
+
+var InvalidInputParametersErr = fmt.Errorf("invalid input parameters")
 
 // IsPodReady tells if a given pod is ready looking at its status.
 func IsPodReady(pod *corev1.Pod) bool {
@@ -21,3 +28,18 @@ func IsPodReady(pod *corev1.Pod) bool {
 
 	return false
 }
+
+func GetPodOrdinal(podName, clusterName string) (int64, error) {
+	// Pod name needs to have at least 2 more characters
+	if len(podName) < len(clusterName)+2 {
+		return -1, fmt.Errorf("pod name (%s) and cluster name (%s): %w", podName, clusterName, InvalidInputParametersErr)
+	}
+
+	// The +1 is for the separator between stateful set name and pod ordinal
+	ordinalStr := podName[len(clusterName)+1:]
+	ordinal, err := strconv.ParseInt(ordinalStr, 10, 0)
+	if err != nil {
+		return -1, fmt.Errorf("parsing int failed (%s): %w", ordinalStr, err)
+	}
+	return ordinal, nil
+}

src/go/k8s/pkg/utils/kubernetes_test.go

@@ -0,0 +1,45 @@
+// Copyright 2022-2023 Redpanda Data, Inc.
+//
+// Use of this software is governed by the Business Source License
+// included in the file licenses/BSL.md
+//
+// As of the Change Date specified in that file, in accordance with
+// the Business Source License, use of this software will be governed
+// by the Apache License, Version 2.0
+
+package utils_test
+
+import (
+	"fmt"
+	"testing"
+
+	"github.com/redpanda-data/redpanda/src/go/k8s/pkg/utils"
+	"github.com/stretchr/testify/require"
+)
+
+func TestGetPodOrdinal(t *testing.T) {
+	tcs := []struct {
+		podName         string
+		clusterName     string
+		expectedError   bool
+		expectedOrdinal int64
+	}{
+		{"", "", true, -1},
+		{"test", "", true, -1},
+		{"pod-0", "pod", false, 0},
+		{"pod-99", "pod", false, 99},
+		{"", "unexpected longer cluster name", true, -1},
+		{"test+0", "test", false, 0},
+		{"without-ordinal-", "without-ordinal", true, -1},
+	}
+
+	for _, tc := range tcs {
+		t.Run(fmt.Sprintf("pod %s and cluster %s", tc.podName, tc.clusterName), func(t *testing.T) {
+			ordinal, err := utils.GetPodOrdinal(tc.podName, tc.clusterName)
+			if tc.expectedError {
+				require.Error(t, err)
+			}
+			require.Equal(t, tc.expectedOrdinal, ordinal)
+		})
+	}
+}