zookeeper-3-nodes.yaml

# Setup Service to provide access to Zookeeper for clients
apiVersion: v1
kind: Service
metadata:
  # DNS would be like zookeeper.zoons
  name: zookeeper
  labels:
    app: zookeeper
spec:
  ports:
    - port: 2181
      name: client
    - port: 7000
      name: prometheus
  selector:
    app: zookeeper
    what: node
---
# Setup Headless Service for StatefulSet
apiVersion: v1
kind: Service
metadata:
  # DNS would be like zookeeper-0.zookeepers.etc
  name: zookeepers
  labels:
    app: zookeeper
spec:
  ports:
    - port: 2888
      name: server
    - port: 3888
      name: leader-election
  clusterIP: None
  selector:
    app: zookeeper
    what: node
---
# Setup max number of unavailable pods in StatefulSet
apiVersion: policy/v1beta1
kind: PodDisruptionBudget
metadata:
  name: zookeeper-pod-disruption-budget
spec:
  selector:
    matchLabels:
      app: zookeeper
  maxUnavailable: 1
---
# Setup Zookeeper StatefulSet
# Possible params:
# 1. replicas
# 2. memory
# 3. cpu
# 4. storage
# 5. storageClassName
# 6. user to run app
apiVersion: apps/v1
kind: StatefulSet
metadata:
  # nodes would be named as zookeeper-0, zookeeper-1, zookeeper-2
  name: zookeeper
spec:
  selector:
    matchLabels:
      app: zookeeper
  serviceName: zookeepers
  replicas: 3
  updateStrategy:
    type: RollingUpdate
  podManagementPolicy: Parallel
  template:
    metadata:
      labels:
        app: zookeeper
        what: node
      annotations:
        prometheus.io/port: '7000'
        prometheus.io/scrape: 'true'
    spec:
      affinity:
        podAntiAffinity:
          requiredDuringSchedulingIgnoredDuringExecution:
            - labelSelector:
                matchExpressions:
                  - key: "app"
                    operator: In
                    values:
                      - zookeeper
              topologyKey: "kubernetes.io/hostname"
      containers:
        - name: kubernetes-zookeeper
          imagePullPolicy: IfNotPresent
          image: "docker.io/zookeeper:3.6.1"
          resources:
            requests:
              memory: "1Gi"
              cpu: "0.5"
          ports:
            - containerPort: 2181
              name: client
            - containerPort: 2888
              name: server
            - containerPort: 3888
              name: leader-election
            - containerPort: 7000
              name: prometheus
# See those links for proper startup settings:
# https://github.com/kow3ns/kubernetes-zookeeper/blob/master/docker/scripts/start-zookeeper
# https://clickhouse.yandex/docs/en/operations/tips/#zookeeper
# https://github.com/ClickHouse/ClickHouse/issues/11781
          command:
            - bash
            - -x
            - -c
            - |
              SERVERS=3 &&
              HOST=`hostname -s` &&
              DOMAIN=`hostname -d` &&
              CLIENT_PORT=2181 &&
              SERVER_PORT=2888 &&
              ELECTION_PORT=3888 &&
              PROMETHEUS_PORT=7000 &&
              ZOO_DATA_DIR=/var/lib/zookeeper/data &&
              ZOO_DATA_LOG_DIR=/var/lib/zookeeper/datalog &&
              {
                echo "clientPort=${CLIENT_PORT}"
                echo 'tickTime=2000'
                echo 'initLimit=300'
                echo 'syncLimit=10'
                echo 'maxClientCnxns=2000'
                echo 'maxSessionTimeout=60000000'
                echo "dataDir=${ZOO_DATA_DIR}"
                echo "dataLogDir=${ZOO_DATA_LOG_DIR}"
                echo 'autopurge.snapRetainCount=10'
                echo 'autopurge.purgeInterval=1'
                echo 'preAllocSize=131072'
                echo 'snapCount=3000000'
                echo 'leaderServes=yes'
                echo 'standaloneEnabled=true'
                echo '4lw.commands.whitelist=stat, ruok, conf, isro'
                echo 'metricsProvider.className=org.apache.zookeeper.metrics.prometheus.PrometheusMetricsProvider'
                echo "metricsProvider.httpPort=${PROMETHEUS_PORT}"
              } > /conf/zoo.cfg &&
              {
                echo "zookeeper.root.logger=CONSOLE"
                echo "zookeeper.console.threshold=INFO"
                echo "log4j.rootLogger=\${zookeeper.root.logger}"
                echo "log4j.appender.CONSOLE=org.apache.log4j.ConsoleAppender"
                echo "log4j.appender.CONSOLE.Threshold=\${zookeeper.console.threshold}"
                echo "log4j.appender.CONSOLE.layout=org.apache.log4j.PatternLayout"
                echo "log4j.appender.CONSOLE.layout.ConversionPattern=%d{ISO8601} [myid:%X{myid}] - %-5p [%t:%C{1}@%L] - %m%n"
              } > /conf/log4j.properties &&
              echo 'JVMFLAGS="-Xms128M -Xmx1G -XX:+UseG1GC -XX:+CMSParallelRemarkEnabled"' > /conf/java.env &&
              if [[ $HOST =~ (.*)-([0-9]+)$ ]]; then
                  NAME=${BASH_REMATCH[1]}
                  ORD=${BASH_REMATCH[2]}
              else
                  echo "Failed to parse name and ordinal of Pod"
                  exit 1
              fi &&
              mkdir -p ${ZOO_DATA_DIR} &&
              mkdir -p ${ZOO_DATA_LOG_DIR} &&
              export MY_ID=$((ORD+1)) &&
              echo $MY_ID > $ZOO_DATA_DIR/myid &&
              if [[ $SERVERS -gt 1 ]]; then
                for (( i=1; i<=$SERVERS; i++ )); do
                    echo "server.$i=$NAME-$((i-1)).$DOMAIN:$SERVER_PORT:$ELECTION_PORT" >> /conf/zoo.cfg;
                done
              fi &&
              chown -Rv zookeeper "$ZOO_DATA_DIR" "$ZOO_DATA_LOG_DIR" "$ZOO_LOG_DIR" "$ZOO_CONF_DIR" &&
              zkServer.sh start-foreground
          readinessProbe:
            exec:
              command:
                - bash
                - -c
                - "OK=$(echo ruok | nc 127.0.0.1 2181); if [[ \"$OK\" == \"imok\" ]]; then exit 0; else exit 1; fi"
            initialDelaySeconds: 10
            timeoutSeconds: 5
          livenessProbe:
            exec:
              command:
                - bash
                - -c
                - "OK=$(echo ruok | nc 127.0.0.1 2181); if [[ \"$OK\" == \"imok\" ]]; then exit 0; else exit 1; fi"
            initialDelaySeconds: 10
            timeoutSeconds: 5
          volumeMounts:
            - name: datadir-volume
              mountPath: /var/lib/zookeeper
      # Run as a non-privileged user
      securityContext:
        runAsUser: 1000
        fsGroup: 1000
      volumes:
        - name: datadir-volume
          emptyDir:
            medium: "" #accepted values:  empty str (means node's default medium) or Memory
            sizeLimit: 1Gi