[Feature] ArangoClusterSynchronization controller (TG-190) (#876)

* [Feature] ArangoClusterSynchronization controller (TG-190)

* helm chart

* Fix model

CHANGELOG.md

@@ -13,6 +13,7 @@
 - Add ArangoJob and Apps Operator
 - Use Go 1.17
 - Add metrics for the plan actions
+- Add ArangoClusterSynchronization Operator
 
 ## [1.2.6](https://github.com/arangodb/kube-arangodb/tree/1.2.6) (2021-12-15)
 - Add ArangoBackup backoff functionality

Makefile

@@ -98,6 +98,7 @@ MANIFESTPATHDEPLOYMENT := manifests/arango-deployment$(MANIFESTSUFFIX).yaml
 MANIFESTPATHDEPLOYMENTREPLICATION := manifests/arango-deployment-replication$(MANIFESTSUFFIX).yaml
 MANIFESTPATHBACKUP := manifests/arango-backup$(MANIFESTSUFFIX).yaml
 MANIFESTPATHAPPS := manifests/arango-apps$(MANIFESTSUFFIX).yaml
+MANIFESTPATHK2KCLUSTERSYNC := manifests/arango-k2kclustersync$(MANIFESTSUFFIX).yaml
 MANIFESTPATHSTORAGE := manifests/arango-storage$(MANIFESTSUFFIX).yaml
 MANIFESTPATHALL := manifests/arango-all$(MANIFESTSUFFIX).yaml
 MANIFESTPATHTEST := manifests/arango-test$(MANIFESTSUFFIX).yaml
@@ -106,6 +107,7 @@ KUSTOMIZEPATHDEPLOYMENT := manifests/kustomize/deployment/arango-deployment$(MAN
 KUSTOMIZEPATHDEPLOYMENTREPLICATION := manifests/kustomize/deployment-replication/arango-deployment-replication$(MANIFESTSUFFIX).yaml
 KUSTOMIZEPATHBACKUP := manifests/kustomize/backup/arango-backup$(MANIFESTSUFFIX).yaml
 KUSTOMIZEPATHAPPS := manifests/kustomize/apps/arango-apps$(MANIFESTSUFFIX).yaml
+KUSTOMIZEPATHK2KCLUSTERSYNC := manifests/kustomize/apps/arango-k2kclustersync$(MANIFESTSUFFIX).yaml
 KUSTOMIZEPATHSTORAGE := manifests/kustomize/storage/arango-storage$(MANIFESTSUFFIX).yaml
 KUSTOMIZEPATHALL := manifests/kustomize/all/arango-all$(MANIFESTSUFFIX).yaml
 KUSTOMIZEPATHTEST := manifests/kustomize/test/arango-test$(MANIFESTSUFFIX).yaml
@@ -333,6 +335,7 @@ $(eval $(call manifest-generator, deployment, kube-arangodb, \
 	   --set "operator.features.deploymentReplications=false" \
 	   --set "operator.features.storage=false" \
 	   --set "operator.features.apps=false" \
+	   --set "operator.features.k8sToK8sClusterSync=false" \
 	   --set "operator.features.backup=false"))
 
 $(eval $(call manifest-generator, deployment-replication, kube-arangodb, \
@@ -340,6 +343,7 @@ $(eval $(call manifest-generator, deployment-replication, kube-arangodb, \
        --set "operator.features.deploymentReplications=true" \
        --set "operator.features.storage=false" \
        --set "operator.features.apps=false" \
+       --set "operator.features.k8sToK8sClusterSync=false" \
        --set "operator.features.backup=false"))
 
 $(eval $(call manifest-generator, storage, kube-arangodb, \
@@ -347,6 +351,7 @@ $(eval $(call manifest-generator, storage, kube-arangodb, \
        --set "operator.features.deploymentReplications=false" \
        --set "operator.features.storage=true" \
        --set "operator.features.apps=false" \
+       --set "operator.features.k8sToK8sClusterSync=false" \
        --set "operator.features.backup=false"))
 
 $(eval $(call manifest-generator, backup, kube-arangodb, \
@@ -354,6 +359,7 @@ $(eval $(call manifest-generator, backup, kube-arangodb, \
        --set "operator.features.deploymentReplications=false" \
        --set "operator.features.storage=false" \
        --set "operator.features.apps=false" \
+       --set "operator.features.k8sToK8sClusterSync=false" \
        --set "operator.features.backup=true"))
 
 $(eval $(call manifest-generator, apps, kube-arangodb, \
@@ -361,6 +367,15 @@ $(eval $(call manifest-generator, apps, kube-arangodb, \
        --set "operator.features.deploymentReplications=false" \
        --set "operator.features.storage=false" \
        --set "operator.features.apps=true" \
+       --set "operator.features.k8sToK8sClusterSync=false" \
+       --set "operator.features.backup=false"))
+
+$(eval $(call manifest-generator, k2kclustersync, kube-arangodb, \
+       --set "operator.features.deployment=false" \
+       --set "operator.features.deploymentReplications=false" \
+       --set "operator.features.storage=false" \
+       --set "operator.features.apps=false" \
+       --set "operator.features.k8sToK8sClusterSync=true" \
        --set "operator.features.backup=false"))
 
 $(eval $(call manifest-generator, all, kube-arangodb, \
@@ -368,6 +383,7 @@ $(eval $(call manifest-generator, all, kube-arangodb, \
        --set "operator.features.deploymentReplications=true" \
        --set "operator.features.storage=true" \
        --set "operator.features.apps=true" \
+       --set "operator.features.k8sToK8sClusterSync=true" \
        --set "operator.features.backup=true"))
 
 .PHONY: chart-crd

chart/kube-arangodb-crd/templates/k2kclustersync.yaml

@@ -0,0 +1,39 @@
+apiVersion: apiextensions.k8s.io/v1
+kind: CustomResourceDefinition
+metadata:
+  name: arangoclustersynchronizations.database.arangodb.com
+  labels:
+    app.kubernetes.io/name: {{ template "kube-arangodb-crd.name" . }}
+    helm.sh/chart: {{ .Chart.Name }}-{{ .Chart.Version }}
+    app.kubernetes.io/managed-by: {{ .Release.Service }}
+    app.kubernetes.io/instance: {{ .Release.Name }}
+    release: {{ .Release.Name }}
+spec:
+  group: database.arangodb.com
+  names:
+    kind: ArangoClusterSynchronization
+    listKind: ArangoClusterSynchronizationList
+    plural: arangoclustersynchronizations
+    singular: arangoclustersynchronization
+    shortNames:
+      - arangoclustersync
+  scope: Namespaced
+  versions:
+    - name: v1
+      schema:
+        openAPIV3Schema:
+          type: object
+          x-kubernetes-preserve-unknown-fields: true
+      served: true
+      storage: true
+      subresources:
+        status: {}
+    - name: v2alpha1
+      schema:
+        openAPIV3Schema:
+          type: object
+          x-kubernetes-preserve-unknown-fields: true
+      served: true
+      storage: false
+      subresources:
+        status: {}

chart/kube-arangodb/README.md

@@ -24,6 +24,9 @@ Possible Operators:
 - `ArangoDeployment` - enabled by default
 - `ArangoDeploymentReplications` - enabled by default
 - `ArangoLocalStorage` - disabled by default
+- `ArangoBackup` - disabled by default
+- `ArangoJob` - disabled by default
+- `ArangoClusterSynchronization` - disabled by default
 
 To install Operators in mode "One per Helm Release" we can use:
 
@@ -31,19 +34,10 @@ To install Operators in mode "One per Helm Release" we can use:
 helm install --name arango-deployment kube-arangodb.tar.gz \
              --set operator.features.deployment=true \
              --set operator.features.deploymentReplications=false \
-             --set operator.features.storage=false
+             --set operator.features.storage=false \
-
+             --set operator.features.backup=false \
-
+             --set operator.features.apps=false \
-helm install --name arango-deployment-replications kube-arangodb.tar.gz \
+             --set operator.features.k8sToK8sClusterSync=false
-             --set operator.features.deployment=false \
-             --set operator.features.deploymentReplications=true \
-             --set operator.features.storage=false
-
-
-helm install --name arango-storage kube-arangodb.tar.gz \
-             --set operator.features.deployment=false \
-             --set operator.features.deploymentReplications=false \
-             --set operator.features.storage=true
 ```
 
 
@@ -155,6 +149,18 @@ Define if ArangoBackup Operator should be enabled.
 
 Default: `false`
 
+### `operator.features.apps`
+
+Define if ArangoJob Operator should be enabled.
+
+Default: `false`
+
+### `operator.features.k8sToK8sClusterSync`
+
+Define if ArangoClusterSynchronization Operator should be enabled.
+
+Default: `false`
+
 ### `rbac.enabled`
 
 Define if RBAC should be enabled.

chart/kube-arangodb/templates/deployment.yaml

@@ -105,6 +105,9 @@ spec:
 {{- end }}
 {{ if .Values.operator.features.apps }}
                     - --operator.apps
+{{- end }}
+{{ if .Values.operator.features.k8sToK8sClusterSync }}
+                    - --operator.k2k-cluster-sync
 {{- end }}
                     - --chaos.allowed={{ .Values.operator.allowChaos }}
 {{- if .Values.operator.args }}

chart/kube-arangodb/templates/k2k-cluster-sync-operator/cluster-role-binding.yaml

@@ -0,0 +1,26 @@
+{{ if .Values.rbac.enabled -}}
+{{ if not (eq .Values.operator.scope "namespaced") -}}
+{{ if .Values.operator.features.k8sToK8sClusterSync -}}
+
+apiVersion: rbac.authorization.k8s.io/v1
+kind: ClusterRoleBinding
+metadata:
+    name: {{ template "kube-arangodb.rbac-cluster" . }}-k2kclustersync
+    labels:
+        app.kubernetes.io/name: {{ template "kube-arangodb.name" . }}
+        helm.sh/chart: {{ .Chart.Name }}-{{ .Chart.Version }}
+        app.kubernetes.io/managed-by: {{ .Release.Service }}
+        app.kubernetes.io/instance: {{ .Release.Name }}
+        release: {{ .Release.Name }}
+roleRef:
+    apiGroup: rbac.authorization.k8s.io
+    kind: ClusterRole
+    name: {{ template "kube-arangodb.rbac-cluster" . }}-k2kclustersync
+subjects:
+    - kind: ServiceAccount
+      name: {{ template "kube-arangodb.operatorName" . }}
+      namespace: {{ .Release.Namespace }}
+
+{{- end }}
+{{- end }}
+{{- end }}

chart/kube-arangodb/templates/k2k-cluster-sync-operator/cluster-role.yaml

@@ -0,0 +1,22 @@
+{{ if .Values.rbac.enabled -}}
+{{ if not (eq .Values.operator.scope "namespaced") -}}
+{{ if .Values.operator.features.k8sToK8sClusterSync -}}
+
+apiVersion: rbac.authorization.k8s.io/v1
+kind: ClusterRole
+metadata:
+    name: {{ template "kube-arangodb.rbac-cluster" . }}-k2kclustersync
+    labels:
+        app.kubernetes.io/name: {{ template "kube-arangodb.name" . }}
+        helm.sh/chart: {{ .Chart.Name }}-{{ .Chart.Version }}
+        app.kubernetes.io/managed-by: {{ .Release.Service }}
+        app.kubernetes.io/instance: {{ .Release.Name }}
+        release: {{ .Release.Name }}
+rules:
+    - apiGroups: ["apiextensions.k8s.io"]
+      resources: ["customresourcedefinitions"]
+      verbs: ["get", "list", "watch"]
+
+{{- end }}
+{{- end }}
+{{- end }}

chart/kube-arangodb/templates/k2k-cluster-sync-operator/role-binding.yaml

@@ -0,0 +1,25 @@
+{{ if .Values.rbac.enabled -}}
+{{ if .Values.operator.features.k8sToK8sClusterSync -}}
+
+apiVersion: rbac.authorization.k8s.io/v1
+kind: RoleBinding
+metadata:
+    name: {{ template "kube-arangodb.rbac" . }}-k2kclustersync
+    namespace: {{ .Release.Namespace }}
+    labels:
+        app.kubernetes.io/name: {{ template "kube-arangodb.name" . }}
+        helm.sh/chart: {{ .Chart.Name }}-{{ .Chart.Version }}
+        app.kubernetes.io/managed-by: {{ .Release.Service }}
+        app.kubernetes.io/instance: {{ .Release.Name }}
+        release: {{ .Release.Name }}
+roleRef:
+    apiGroup: rbac.authorization.k8s.io
+    kind: Role
+    name: {{ template "kube-arangodb.rbac" . }}-k2kclustersync
+subjects:
+    - kind: ServiceAccount
+      name: {{ template "kube-arangodb.operatorName" . }}
+      namespace: {{ .Release.Namespace }}
+
+{{- end }}
+{{- end }}

chart/kube-arangodb/templates/k2k-cluster-sync-operator/role.yaml

@@ -0,0 +1,33 @@
+{{ if .Values.rbac.enabled -}}
+{{ if .Values.operator.features.k8sToK8sClusterSync -}}
+
+apiVersion: rbac.authorization.k8s.io/v1
+kind: Role
+metadata:
+    name: {{ template "kube-arangodb.rbac" . }}-k2kclustersync
+    namespace: {{ .Release.Namespace }}
+    labels:
+        app.kubernetes.io/name: {{ template "kube-arangodb.name" . }}
+        helm.sh/chart: {{ .Chart.Name }}-{{ .Chart.Version }}
+        app.kubernetes.io/managed-by: {{ .Release.Service }}
+        app.kubernetes.io/instance: {{ .Release.Name }}
+        release: {{ .Release.Name }}
+rules:
+    - apiGroups: [""]
+      resources: ["pods", "services", "endpoints"]
+      verbs: ["get", "update"]
+    - apiGroups: [""]
+      resources: ["events"]
+      verbs: ["*"]
+    - apiGroups: [""]
+      resources: ["secrets"]
+      verbs: ["get"]
+    - apiGroups: ["apps"]
+      resources: ["deployments", "replicasets"]
+      verbs: ["get"]
+    - apiGroups: ["database.arangodb.com"]
+      resources: ["arangodeployments", "arangoclustersynchronizations"]
+      verbs: ["get", "list", "watch"]
+
+{{- end }}
+{{- end }}

chart/kube-arangodb/values.yaml

@@ -39,6 +39,7 @@ operator:
     storage: false
     backup: false
     apps: false
+    k8sToK8sClusterSync: false
 
   images:
     base: alpine:3.11

cmd/main.go

@@ -113,6 +113,7 @@ var (
 		enableBackup                bool // Run backup operator
 		enableApps                  bool // Run apps operator
 		versionOnly                 bool // Run only version endpoint, explicitly disabled with other
+		enableK2KClusterSync        bool // Run k2kClusterSync operator
 
 		scalingIntegrationEnabled bool
 
@@ -141,6 +142,7 @@ var (
 	storageProbe               probe.ReadyProbe
 	backupProbe                probe.ReadyProbe
 	appsProbe                  probe.ReadyProbe
+	k2KClusterSyncProbe        probe.ReadyProbe
 )
 
 func init() {
@@ -157,6 +159,7 @@ func init() {
 	f.BoolVar(&operatorOptions.enableStorage, "operator.storage", false, "Enable to run the ArangoLocalStorage operator")
 	f.BoolVar(&operatorOptions.enableBackup, "operator.backup", false, "Enable to run the ArangoBackup operator")
 	f.BoolVar(&operatorOptions.enableApps, "operator.apps", false, "Enable to run the ArangoApps operator")
+	f.BoolVar(&operatorOptions.enableK2KClusterSync, "operator.k2k-cluster-sync", false, "Enable to run the ArangoClusterSynchronizations operator")
 	f.BoolVar(&operatorOptions.versionOnly, "operator.version", false, "Enable only version endpoint in Operator")
 	f.StringVar(&operatorOptions.alpineImage, "operator.alpine-image", UBIImageEnv.GetOrDefault(defaultAlpineImage), "Docker image used for alpine containers")
 	f.MarkDeprecated("operator.alpine-image", "Value is not used anymore")
@@ -225,12 +228,13 @@ func executeMain(cmd *cobra.Command, args []string) {
 	klog.Flush()
 
 	// Check operating mode
-	if !operatorOptions.enableDeployment && !operatorOptions.enableDeploymentReplication && !operatorOptions.enableStorage && !operatorOptions.enableBackup && !operatorOptions.enableApps {
+	if !operatorOptions.enableDeployment && !operatorOptions.enableDeploymentReplication && !operatorOptions.enableStorage &&
+		!operatorOptions.enableBackup && !operatorOptions.enableApps && !operatorOptions.enableK2KClusterSync {
 		if !operatorOptions.versionOnly {
-			cliLog.Fatal().Err(err).Msg("Turn on --operator.deployment, --operator.deployment-replication, --operator.storage, --operator.backup, --operator.apps or any combination of these")
+			cliLog.Fatal().Err(err).Msg("Turn on --operator.deployment, --operator.deployment-replication, --operator.storage, --operator.backup, --operator.apps, --operator.k2k-cluster-sync or any combination of these")
 		}
 	} else if operatorOptions.versionOnly {
-		cliLog.Fatal().Err(err).Msg("Options --operator.deployment, --operator.deployment-replication, --operator.storage, --operator.backup, --operator.apps cannot be enabled together with --operator.version")
+		cliLog.Fatal().Err(err).Msg("Options --operator.deployment, --operator.deployment-replication, --operator.storage, --operator.backup, --operator.apps, --operator.k2k-cluster-sync cannot be enabled together with --operator.version")
 	}
 
 	// Log version
@@ -307,6 +311,10 @@ func executeMain(cmd *cobra.Command, args []string) {
 				Enabled: cfg.EnableApps,
 				Probe:   &appsProbe,
 			},
+			ClusterSync: server.OperatorDependency{
+				Enabled: cfg.EnableK2KClusterSync,
+				Probe:   &k2KClusterSyncProbe,
+			},
 			Operators: o,
 
 			Secrets: secrets,
@@ -394,6 +402,7 @@ func newOperatorConfigAndDeps(id, namespace, name string) (operator.Config, oper
 		EnableStorage:               operatorOptions.enableStorage,
 		EnableBackup:                operatorOptions.enableBackup,
 		EnableApps:                  operatorOptions.enableApps,
+		EnableK2KClusterSync:        operatorOptions.enableK2KClusterSync,
 		AllowChaos:                  chaosOptions.allowed,
 		ScalingIntegrationEnabled:   operatorOptions.scalingIntegrationEnabled,
 		ArangoImage:                 operatorOptions.arangoImage,
@@ -413,6 +422,7 @@ func newOperatorConfigAndDeps(id, namespace, name string) (operator.Config, oper
 		StorageProbe:               &storageProbe,
 		BackupProbe:                &backupProbe,
 		AppsProbe:                  &appsProbe,
+		K2KClusterSyncProbe:        &k2KClusterSyncProbe,
 	}
 
 	return cfg, deps, nil

examples/arangoclustersync.yaml

@@ -0,0 +1,5 @@
+apiVersion: database.arangodb.com/v1
+kind: ArangoClusterSynchronization
+metadata:
+  name: arangoclustersync-sample
+spec:

manifests/kustomize/k2kclustersync/kustomization.yaml

@@ -0,0 +1,5 @@
+apiVersion: kustomize.config.k8s.io/v1beta1
+kind: Kustomization
+
+resources:
+  - arango-k2kclustersync.yaml

pkg/apis/deployment/definitions.go

@@ -40,4 +40,5 @@ const (
 
 var (
 	ArangoDeploymentShortNames             = []string{"arangodb", "arango"}
+	ArangoClusterSynchronizationShortNames = []string{"arangoclustersync"}
 )

pkg/apis/deployment/v1/register.go

@@ -52,6 +52,8 @@ func addKnownTypes(s *runtime.Scheme) error {
 		&ArangoDeploymentList{},
 		&ArangoMember{},
 		&ArangoMemberList{},
+		&ArangoClusterSynchronization{},
+		&ArangoClusterSynchronizationList{},
 	)
 	metav1.AddToGroupVersion(s, SchemeGroupVersion)
 	return nil

pkg/apis/deployment/v2alpha1/register.go

@@ -52,6 +52,8 @@ func addKnownTypes(s *runtime.Scheme) error {
 		&ArangoDeploymentList{},
 		&ArangoMember{},
 		&ArangoMemberList{},
+		&ArangoClusterSynchronization{},
+		&ArangoClusterSynchronizationList{},
 	)
 	metav1.AddToGroupVersion(s, SchemeGroupVersion)
 	return nil

pkg/handlers/clustersync/handler.go

@@ -0,0 +1,80 @@
+//
+// DISCLAIMER
+//
+// Copyright 2016-2021 ArangoDB GmbH, Cologne, Germany
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+// Copyright holder is ArangoDB GmbH, Cologne, Germany
+//
+
+package clustersync
+
+import (
+	"context"
+
+	"github.com/arangodb/kube-arangodb/pkg/apis/apps"
+	appsApi "github.com/arangodb/kube-arangodb/pkg/apis/apps/v1"
+	"github.com/arangodb/kube-arangodb/pkg/apis/deployment"
+	arangoClientSet "github.com/arangodb/kube-arangodb/pkg/generated/clientset/versioned"
+	operator "github.com/arangodb/kube-arangodb/pkg/operatorV2"
+	"github.com/arangodb/kube-arangodb/pkg/operatorV2/event"
+	"github.com/arangodb/kube-arangodb/pkg/operatorV2/operation"
+	"github.com/arangodb/kube-arangodb/pkg/util/k8sutil"
+
+	meta "k8s.io/apimachinery/pkg/apis/meta/v1"
+	"k8s.io/client-go/kubernetes"
+)
+
+type handler struct {
+	client        arangoClientSet.Interface
+	kubeClient    kubernetes.Interface
+	eventRecorder event.RecorderInstance
+
+	operator operator.Operator
+}
+
+func (*handler) Name() string {
+	return deployment.ArangoClusterSynchronizationResourceKind
+}
+
+func (h *handler) Handle(item operation.Item) error {
+	// Do not act on delete event
+	if item.Operation == operation.Delete {
+		return nil
+	}
+
+	// Get ClusterSynchronizations object. It also covers NotFound case
+	clusterSync, err := h.client.DatabaseV1().ArangoClusterSynchronizations(item.Namespace).Get(context.Background(), item.Name, meta.GetOptions{})
+	if err != nil {
+		if k8sutil.IsNotFound(err) {
+			return nil
+		}
+		h.operator.GetLogger().Error().Msgf("ArangoClusterSynchronizations fetch error %v", err)
+		return err
+	}
+
+	// Update status on object
+	if _, err = h.client.DatabaseV1().ArangoClusterSynchronizations(item.Namespace).UpdateStatus(context.Background(), clusterSync, meta.UpdateOptions{}); err != nil {
+		h.operator.GetLogger().Error().Msgf("ArangoClusterSynchronizations status update error %v", err)
+		return err
+	}
+
+	return nil
+}
+
+func (*handler) CanBeHandled(item operation.Item) bool {
+	return item.Group == appsApi.SchemeGroupVersion.Group &&
+		item.Version == appsApi.SchemeGroupVersion.Version &&
+		item.Kind == apps.ArangoJobResourceKind
+}

pkg/handlers/clustersync/lifecycle.go

@@ -0,0 +1,57 @@
+//
+// DISCLAIMER
+//
+// Copyright 2016-2021 ArangoDB GmbH, Cologne, Germany
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+// Copyright holder is ArangoDB GmbH, Cologne, Germany
+//
+
+package clustersync
+
+import (
+	"context"
+	"time"
+
+	"github.com/arangodb/kube-arangodb/pkg/apis/deployment"
+	operator "github.com/arangodb/kube-arangodb/pkg/operatorV2"
+
+	"github.com/rs/zerolog/log"
+	meta "k8s.io/apimachinery/pkg/apis/meta/v1"
+)
+
+var _ operator.LifecyclePreStart = &handler{}
+
+// LifecyclePreStart is executed before operator starts to work, additional checks can be placed here
+// Wait for CR to be present
+func (h *handler) LifecyclePreStart() error {
+	log.Info().Msgf("Starting Lifecycle PreStart for %s", h.Name())
+
+	defer func() {
+		log.Info().Msgf("Lifecycle PreStart for %s completed", h.Name())
+	}()
+
+	for {
+		_, err := h.client.DatabaseV1().ArangoClusterSynchronizations(h.operator.Namespace()).List(context.Background(), meta.ListOptions{})
+
+		if err != nil {
+			log.Warn().Err(err).Msgf("CR for %s not found", deployment.ArangoClusterSynchronizationResourceKind)
+
+			time.Sleep(250 * time.Millisecond)
+			continue
+		}
+
+		return nil
+	}
+}

pkg/handlers/clustersync/register.go

@@ -0,0 +1,62 @@
+//
+// DISCLAIMER
+//
+// Copyright 2016-2021 ArangoDB GmbH, Cologne, Germany
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+// Copyright holder is ArangoDB GmbH, Cologne, Germany
+//
+
+package clustersync
+
+import (
+	"github.com/arangodb/kube-arangodb/pkg/apis/deployment"
+	v1 "github.com/arangodb/kube-arangodb/pkg/apis/deployment/v1"
+	arangoClientSet "github.com/arangodb/kube-arangodb/pkg/generated/clientset/versioned"
+	arangoInformer "github.com/arangodb/kube-arangodb/pkg/generated/informers/externalversions"
+	operator "github.com/arangodb/kube-arangodb/pkg/operatorV2"
+	"github.com/arangodb/kube-arangodb/pkg/operatorV2/event"
+
+	"k8s.io/client-go/kubernetes"
+)
+
+func newEventInstance(eventRecorder event.Recorder) event.RecorderInstance {
+	return eventRecorder.NewInstance(v1.SchemeGroupVersion.Group,
+		v1.SchemeGroupVersion.Version,
+		deployment.ArangoClusterSynchronizationResourceKind)
+}
+
+// RegisterInformer into operator
+func RegisterInformer(operator operator.Operator, recorder event.Recorder, client arangoClientSet.Interface, kubeClient kubernetes.Interface, informer arangoInformer.SharedInformerFactory) error {
+	if err := operator.RegisterInformer(informer.Database().V1().ArangoClusterSynchronizations().Informer(),
+		v1.SchemeGroupVersion.Group,
+		v1.SchemeGroupVersion.Version,
+		deployment.ArangoClusterSynchronizationResourceKind); err != nil {
+		return err
+	}
+
+	h := &handler{
+		client:        client,
+		kubeClient:    kubeClient,
+		eventRecorder: newEventInstance(recorder),
+
+		operator: operator,
+	}
+
+	if err := operator.RegisterHandler(h); err != nil {
+		return err
+	}
+
+	return nil
+}

pkg/handlers/job/job_suite_test.go

@@ -27,8 +27,7 @@ import (
 	"github.com/arangodb/kube-arangodb/pkg/apis/apps"
 	appsApi "github.com/arangodb/kube-arangodb/pkg/apis/apps/v1"
 	"github.com/arangodb/kube-arangodb/pkg/apis/deployment"
-	database "github.com/arangodb/kube-arangodb/pkg/apis/deployment/v1"
+	deploymentApi "github.com/arangodb/kube-arangodb/pkg/apis/deployment/v1"
-	deploymentApi "github.com/arangodb/kube-arangodb/pkg/apis/deployment/v2alpha1"
 	fakeClientSet "github.com/arangodb/kube-arangodb/pkg/generated/clientset/versioned/fake"
 	operator "github.com/arangodb/kube-arangodb/pkg/operatorV2"
 	"github.com/arangodb/kube-arangodb/pkg/operatorV2/event"
@@ -95,7 +94,7 @@ func createK8sJob(t *testing.T, h *handler, jobs ...*batchv1.Job) {
 	}
 }
 
-func createArangoDeployment(t *testing.T, h *handler, deployments ...*database.ArangoDeployment) {
+func createArangoDeployment(t *testing.T, h *handler, deployments ...*deploymentApi.ArangoDeployment) {
 	for _, deployment := range deployments {
 		_, err := h.client.DatabaseV1().ArangoDeployments(deployment.Namespace).Create(context.Background(), deployment, meta.CreateOptions{})
 		require.NoError(t, err)
@@ -133,8 +132,8 @@ func newArangoJob(name, namespace, deployment string) *appsApi.ArangoJob {
 	}
 }
 
-func newArangoDeployment(name, namespace string) *database.ArangoDeployment {
+func newArangoDeployment(name, namespace string) *deploymentApi.ArangoDeployment {
-	return &database.ArangoDeployment{
+	return &deploymentApi.ArangoDeployment{
 		TypeMeta: meta.TypeMeta{
 			APIVersion: deploymentApi.SchemeGroupVersion.String(),
 			Kind:       deployment.ArangoDeploymentResourceKind,

pkg/operator/crd.go

@@ -17,89 +17,38 @@
 //
 // Copyright holder is ArangoDB GmbH, Cologne, Germany
 //
-// Author Ewout Prangsma
-//
 
 package operator
 
 import (
-	"context"
+	"time"
 
-	"github.com/arangodb/kube-arangodb/pkg/apis/backup"
-	"github.com/arangodb/kube-arangodb/pkg/apis/deployment"
-	"github.com/arangodb/kube-arangodb/pkg/apis/replication"
-	lsapi "github.com/arangodb/kube-arangodb/pkg/apis/storage/v1alpha"
 	"github.com/arangodb/kube-arangodb/pkg/util/crd"
-	"github.com/arangodb/kube-arangodb/pkg/util/errors"
-	meta "k8s.io/apimachinery/pkg/apis/meta/v1"
 )
 
-// waitForCRD waits for the CustomResourceDefinition (created externally)
+// waitForCRD waits for the CustomResourceDefinition (created externally) to be ready.
-// to be ready.
+func (o *Operator) waitForCRD(crdName string, checkFn func() error) {
-func (o *Operator) waitForCRD(enableDeployment, enableDeploymentReplication, enableStorage, enableBackup bool) error {
 	log := o.log
+	log.Debug().Msgf("Waiting for %s CRD to be ready - ", crdName)
 
+	for {
+		var err error = nil
 		if o.Scope.IsNamespaced() {
-		if enableDeployment {
+			if checkFn != nil {
-			log.Debug().Msg("Waiting for ArangoDeployment CRD to be ready")
+				err = crd.WaitReady(checkFn)
-			if err := crd.WaitReady(func() error {
-				_, err := o.CRCli.DatabaseV1().ArangoDeployments(o.Namespace).List(context.Background(), meta.ListOptions{})
-				return err
-			}); err != nil {
-				return errors.WithStack(err)
-			}
-		}
-
-		if enableDeploymentReplication {
-			log.Debug().Msg("Waiting for ArangoDeploymentReplication CRD to be ready")
-			if err := crd.WaitReady(func() error {
-				_, err := o.CRCli.ReplicationV1().ArangoDeploymentReplications(o.Namespace).List(context.Background(), meta.ListOptions{})
-				return err
-			}); err != nil {
-				return errors.WithStack(err)
-			}
-		}
-
-		if enableBackup {
-			log.Debug().Msg("Wait for ArangoBackup CRD to be ready")
-			if err := crd.WaitReady(func() error {
-				_, err := o.CRCli.BackupV1().ArangoBackups(o.Namespace).List(context.Background(), meta.ListOptions{})
-				return err
-			}); err != nil {
-				return errors.WithStack(err)
-			}
 			}
 		} else {
-		if enableDeployment {
+			err = crd.WaitCRDReady(o.KubeExtCli, crdName)
-			log.Debug().Msg("Waiting for ArangoDeployment CRD to be ready")
-			if err := crd.WaitCRDReady(o.KubeExtCli, deployment.ArangoDeploymentCRDName); err != nil {
-				return errors.WithStack(err)
-			}
 		}
 
-		if enableDeploymentReplication {
+		if err == nil {
-			log.Debug().Msg("Waiting for ArangoDeploymentReplication CRD to be ready")
+			break
-			if err := crd.WaitCRDReady(o.KubeExtCli, replication.ArangoDeploymentReplicationCRDName); err != nil {
+		} else {
-				return errors.WithStack(err)
+			log.Error().Err(err).Msg("Resource initialization failed")
-			}
+			log.Info().Msgf("Retrying in %s...", initRetryWaitTime)
-		}
+			time.Sleep(initRetryWaitTime)
-
-		if enableStorage {
-			log.Debug().Msg("Waiting for ArangoLocalStorage CRD to be ready")
-			if err := crd.WaitCRDReady(o.KubeExtCli, lsapi.ArangoLocalStorageCRDName); err != nil {
-				return errors.WithStack(err)
-			}
-		}
-
-		if enableBackup {
-			log.Debug().Msg("Wait for ArangoBackup CRD to be ready")
-			if err := crd.WaitCRDReady(o.KubeExtCli, backup.ArangoBackupCRDName); err != nil {
-				return errors.WithStack(err)
-			}
 		}
 	}
 
 	log.Debug().Msg("CRDs ready")
-
-	return nil
 }

pkg/operator/operator.go

@@ -31,14 +31,18 @@ import (
 	monitoringClient "github.com/prometheus-operator/prometheus-operator/pkg/client/versioned/typed/monitoring/v1"
 	"github.com/prometheus/client_golang/prometheus"
 	"github.com/rs/zerolog"
-	"github.com/rs/zerolog/log"
 	apiextensionsclient "k8s.io/apiextensions-apiserver/pkg/client/clientset/clientset"
+	meta "k8s.io/apimachinery/pkg/apis/meta/v1"
 	kwatch "k8s.io/apimachinery/pkg/watch"
 	"k8s.io/client-go/kubernetes"
 	"k8s.io/client-go/rest"
 	"k8s.io/client-go/tools/record"
 
+	"github.com/arangodb/kube-arangodb/pkg/apis/apps"
+	backupdef "github.com/arangodb/kube-arangodb/pkg/apis/backup"
+	depldef "github.com/arangodb/kube-arangodb/pkg/apis/deployment"
 	deplapi "github.com/arangodb/kube-arangodb/pkg/apis/deployment/v1"
+	repldef "github.com/arangodb/kube-arangodb/pkg/apis/replication"
 	replapi "github.com/arangodb/kube-arangodb/pkg/apis/replication/v1"
 	lsapi "github.com/arangodb/kube-arangodb/pkg/apis/storage/v1alpha"
 	"github.com/arangodb/kube-arangodb/pkg/deployment"
@@ -46,6 +50,7 @@ import (
 	arangoClientSet "github.com/arangodb/kube-arangodb/pkg/generated/clientset/versioned"
 	arangoInformer "github.com/arangodb/kube-arangodb/pkg/generated/informers/externalversions"
 	"github.com/arangodb/kube-arangodb/pkg/handlers/backup"
+	"github.com/arangodb/kube-arangodb/pkg/handlers/clustersync"
 	"github.com/arangodb/kube-arangodb/pkg/handlers/job"
 	"github.com/arangodb/kube-arangodb/pkg/handlers/policy"
 	"github.com/arangodb/kube-arangodb/pkg/logging"
@@ -67,6 +72,7 @@ type operatorV2type string
 const (
 	backupOperator         operatorV2type = "backup"
 	appsOperator           operatorV2type = "apps"
+	k2KClusterSyncOperator operatorV2type = "k2kclustersync"
 )
 
 type Event struct {
@@ -98,6 +104,7 @@ type Config struct {
 	EnableStorage               bool
 	EnableBackup                bool
 	EnableApps                  bool
+	EnableK2KClusterSync        bool
 	AllowChaos                  bool
 	ScalingIntegrationEnabled   bool
 	SingleMode                  bool
@@ -117,6 +124,7 @@ type Dependencies struct {
 	StorageProbe               *probe.ReadyProbe
 	BackupProbe                *probe.ReadyProbe
 	AppsProbe                  *probe.ReadyProbe
+	K2KClusterSyncProbe        *probe.ReadyProbe
 }
 
 // NewOperator instantiates a new operator from given config & dependencies.
@@ -169,49 +177,42 @@ func (o *Operator) Run() {
 			go o.runWithoutLeaderElection("arango-apps-operator", constants.AppsLabelRole, o.onStartApps, o.Dependencies.AppsProbe)
 		}
 	}
+	if o.Config.EnableK2KClusterSync {
+		if !o.Config.SingleMode {
+			go o.runLeaderElection("arango-k2k-cluster-sync-operator", constants.ClusterSyncLabelRole, o.onStartK2KClusterSync, o.Dependencies.K2KClusterSyncProbe)
+		} else {
+			go o.runWithoutLeaderElection("arango-k2k-cluster-sync-operator", constants.ClusterSyncLabelRole, o.onStartK2KClusterSync, o.Dependencies.K2KClusterSyncProbe)
+		}
+	}
 	// Wait until process terminates
 	<-context.TODO().Done()
 }
 
 // onStartDeployment starts the deployment operator and run till given channel is closed.
 func (o *Operator) onStartDeployment(stop <-chan struct{}) {
-	for {
+	checkFn := func() error {
-		if err := o.waitForCRD(true, false, false, false); err == nil {
+		_, err := o.CRCli.DatabaseV1().ArangoDeployments(o.Namespace).List(context.Background(), meta.ListOptions{})
-			break
+		return err
-		} else {
-			log.Error().Err(err).Msg("Resource initialization failed")
-			log.Info().Msgf("Retrying in %s...", initRetryWaitTime)
-			time.Sleep(initRetryWaitTime)
-		}
 	}
+	o.waitForCRD(depldef.ArangoDeploymentCRDName, checkFn)
 	o.runDeployments(stop)
 }
 
 // onStartDeploymentReplication starts the deployment replication operator and run till given channel is closed.
 func (o *Operator) onStartDeploymentReplication(stop <-chan struct{}) {
-	for {
+	checkFn := func() error {
-		if err := o.waitForCRD(false, true, false, false); err == nil {
+		_, err := o.CRCli.DatabaseV1().ArangoDeployments(o.Namespace).List(context.Background(), meta.ListOptions{})
-			break
+		return err
-		} else {
-			log.Error().Err(err).Msg("Resource initialization failed")
-			log.Info().Msgf("Retrying in %s...", initRetryWaitTime)
-			time.Sleep(initRetryWaitTime)
-		}
 	}
+	o.waitForCRD(repldef.ArangoDeploymentReplicationCRDName, checkFn)
 	o.runDeploymentReplications(stop)
 }
 
 // onStartStorage starts the storage operator and run till given channel is closed.
 func (o *Operator) onStartStorage(stop <-chan struct{}) {
-	for {
+	o.waitForCRD(lsapi.ArangoLocalStorageCRDName, nil)
-		if err := o.waitForCRD(false, false, true, false); err == nil {
+	o.runDeploymentReplications(stop)
-			break
+
-		} else {
-			log.Error().Err(err).Msg("Resource initialization failed")
-			log.Info().Msgf("Retrying in %s...", initRetryWaitTime)
-			time.Sleep(initRetryWaitTime)
-		}
-	}
 	o.runLocalStorages(stop)
 }
 
@@ -225,17 +226,13 @@ func (o *Operator) onStartApps(stop <-chan struct{}) {
 	o.onStartOperatorV2(appsOperator, stop)
 }
 
+// onStartK2KClusterSync starts the operator and run till given channel is closed.
+func (o *Operator) onStartK2KClusterSync(stop <-chan struct{}) {
+	o.onStartOperatorV2(k2KClusterSyncOperator, stop)
+}
+
 // onStartOperatorV2 run the operatorV2 type
 func (o *Operator) onStartOperatorV2(operatorType operatorV2type, stop <-chan struct{}) {
-	for {
-		if err := o.waitForCRD(false, false, false, true); err == nil {
-			break
-		} else {
-			log.Error().Err(err).Msg("Resource initialization failed")
-			log.Info().Msgf("Retrying in %s...", initRetryWaitTime)
-			time.Sleep(initRetryWaitTime)
-		}
-	}
 	operatorName := fmt.Sprintf("arangodb-%s-operator", operatorType)
 	operator := operatorV2.NewOperator(o.Dependencies.LogService.MustGetLogger(logging.LoggerNameReconciliation), operatorName, o.Namespace, o.OperatorImage)
 
@@ -264,16 +261,45 @@ func (o *Operator) onStartOperatorV2(operatorType operatorV2type, stop <-chan st
 
 	switch operatorType {
 	case appsOperator:
+		checkFn := func() error {
+			_, err := o.CRCli.AppsV1().ArangoJobs(o.Namespace).List(context.Background(), meta.ListOptions{})
+			return err
+		}
+		o.waitForCRD(apps.ArangoJobCRDName, checkFn)
+
 		if err = job.RegisterInformer(operator, eventRecorder, arangoClientSet, kubeClientSet, arangoInformer); err != nil {
 			panic(err)
 		}
 	case backupOperator:
+		checkFn := func() error {
+			_, err := o.CRCli.BackupV1().ArangoBackups(o.Namespace).List(context.Background(), meta.ListOptions{})
+			return err
+		}
+		o.waitForCRD(backupdef.ArangoBackupCRDName, checkFn)
+
 		if err = backup.RegisterInformer(operator, eventRecorder, arangoClientSet, kubeClientSet, arangoInformer); err != nil {
 			panic(err)
 		}
+
+		checkFn = func() error {
+			_, err := o.CRCli.BackupV1().ArangoBackupPolicies(o.Namespace).List(context.Background(), meta.ListOptions{})
+			return err
+		}
+		o.waitForCRD(backupdef.ArangoBackupPolicyCRDName, checkFn)
+
 		if err = policy.RegisterInformer(operator, eventRecorder, arangoClientSet, kubeClientSet, arangoInformer); err != nil {
 			panic(err)
 		}
+	case k2KClusterSyncOperator:
+		checkFn := func() error {
+			_, err := o.CRCli.DatabaseV1().ArangoClusterSynchronizations(o.Namespace).List(context.Background(), meta.ListOptions{})
+			return err
+		}
+		o.waitForCRD(depldef.ArangoClusterSynchronizationCRDName, checkFn)
+
+		if err = clustersync.RegisterInformer(operator, eventRecorder, arangoClientSet, kubeClientSet, arangoInformer); err != nil {
+			panic(err)
+		}
 	}
 
 	if err = operator.RegisterStarter(arangoInformer); err != nil {

pkg/server/server.go

@@ -73,6 +73,7 @@ type Dependencies struct {
 	Storage               OperatorDependency
 	Backup                OperatorDependency
 	Apps                  OperatorDependency
+	ClusterSync           OperatorDependency
 	Operators             Operators
 	Secrets               corev1.SecretInterface
 }

pkg/util/constants/constants.go

@@ -61,6 +61,7 @@ const (
 
 	BackupLabelRole      = "backup/role"
 	AppsLabelRole        = "apps/role"
+	ClusterSyncLabelRole = "clustersync/role"
 	LabelRole            = "role"
 	LabelRoleLeader      = "leader"
 )