feat: add zookeeper cluster mode (#36)

* feat: add zookeeper cluster mode

This will deploy zookeeper in cluster mode:
- 3x Apache Zookeeper (accessible within the cluster only)
- 2 Services (1 cluster communication, 1 client connection)
- **Must have minimum of 4 nodes in K8s cluster**

* feat: add PodDisruptionBudget to Zookeper cluster

* feat: add resources spec to Zookeeper cluster

* fix: zookeeper cluster conf dir

deployment/zookeeper-cluster/kustomization.yml

@@ -0,0 +1,12 @@
+---
+apiVersion: kustomize.config.k8s.io/v1beta1
+kind: Kustomization
+
+commonAnnotations:
+  app.kubernetes.io/managed-by: kustomization
+
+resources:
+- service-client.yml
+- service-server.yml
+- zookeeper.yml
+- pdb.yml

deployment/zookeeper-cluster/pdb.yml

@@ -0,0 +1,9 @@
+apiVersion: policy/v1
+kind: PodDisruptionBudget
+metadata:
+  name: zk-pdb
+spec:
+  selector:
+    matchLabels:
+      app.kubernetes.io/name: zookeeper
+  maxUnavailable: 1

deployment/zookeeper-cluster/service-client.yml

@@ -0,0 +1,13 @@
+apiVersion: v1
+kind: Service
+metadata:
+  name: zookeeper-client
+  labels:
+    app.kubernetes.io/name: zookeeper
+    app.kubernetes.io/part-of: nifi
+spec:
+  ports:
+  - port: 2181
+    name: client
+  selector:
+    app.kubernetes.io/name: zookeeper

deployment/zookeeper-cluster/service-server.yml

@@ -0,0 +1,16 @@
+apiVersion: v1
+kind: Service
+metadata:
+  name: zookeeper-server
+  labels:
+    app.kubernetes.io/name: zookeeper
+    app.kubernetes.io/part-of: nifi
+spec:
+  ports:
+  - port: 2888
+    name: server
+  - port: 3888
+    name: leader-election
+  clusterIP: None
+  selector:
+    app.kubernetes.io/name: zookeeper

deployment/zookeeper-cluster/zookeeper.yml

@@ -0,0 +1,104 @@
+apiVersion: apps/v1
+kind: StatefulSet
+metadata:
+  name: zookeeper
+spec:
+  selector:
+    matchLabels:
+      app.kubernetes.io/name: zookeeper
+  serviceName: zookeeper-server
+  replicas: 3
+  updateStrategy:
+    type: RollingUpdate
+  podManagementPolicy: OrderedReady
+  template:
+    metadata:
+      labels:
+        app.kubernetes.io/name: zookeeper
+    spec:
+      affinity:
+        podAntiAffinity:
+          requiredDuringSchedulingIgnoredDuringExecution:
+            - labelSelector:
+                matchExpressions:
+                  - key: "app.kubernetes.io/name"
+                    operator: In
+                    values:
+                    - zookeeper
+              topologyKey: "kubernetes.io/hostname"
+      containers:
+      - name: zookeeper
+        imagePullPolicy: Always
+        image: "registry.k8s.io/kubernetes-zookeeper:1.0-3.4.10"
+        ports:
+        - containerPort: 2181
+          name: client
+        - containerPort: 2888
+          name: server
+        - containerPort: 3888
+          name: leader-election
+        command:
+        - sh
+        - -c
+        - "start-zookeeper \
+          --servers=3 \
+          --data_dir=/var/lib/zookeeper/data \
+          --data_log_dir=/var/lib/zookeeper/data/log \
+          --conf_dir=/opt/zookeeper/conf \
+          --client_port=2181 \
+          --election_port=3888 \
+          --server_port=2888 \
+          --tick_time=2000 \
+          --init_limit=10 \
+          --sync_limit=5 \
+          --heap=512M \
+          --max_client_cnxns=60 \
+          --snap_retain_count=3 \
+          --purge_interval=12 \
+          --max_session_timeout=40000 \
+          --min_session_timeout=4000 \
+          --log_level=INFO"
+        readinessProbe:
+          exec:
+            command:
+            - sh
+            - -c
+            - "zookeeper-ready 2181"
+          initialDelaySeconds: 10
+          timeoutSeconds: 5
+        livenessProbe:
+          exec:
+            command:
+            - sh
+            - -c
+            - "zookeeper-ready 2181"
+          initialDelaySeconds: 10
+          timeoutSeconds: 5
+        resources:
+          requests:
+            cpu: 200m
+            memory: 500Mi
+          limits:
+            cpu: 200m
+            memory: 500Mi
+        securityContext:
+          allowPrivilegeEscalation: false
+          privileged: false
+          readOnlyRootFilesystem: true
+          capabilities:
+            drop:
+              - ALL
+        volumeMounts:
+        - name: data
+          mountPath: /var/lib/zookeeper
+          subPath: zookeeper
+        - name: data
+          mountPath: /opt/zookeeper/conf
+          subPath: conf
+      securityContext:
+        runAsUser: 1000
+        fsGroup: 1000
+      volumes:
+        - name: data
+          emptyDir:
+            sizeLimit: 2Gi