Kubernetes 安装

This page describes how to deploy a Flink job and session cluster on Kubernetes.

Setup Kubernetes

Please follow Kubernetes’ setup guide in order to deploy a Kubernetes cluster. If you want to run Kubernetes locally, we recommend using MiniKube.

Note: If using MiniKube please make sure to execute minikube ssh 'sudo ip link set docker0 promisc on' before deploying a Flink cluster. Otherwise Flink components are not able to self reference themselves through a Kubernetes service.

A Flink session cluster is executed as a long-running Kubernetes Deployment. Note that you can run multiple Flink jobs on a session cluster. Each job needs to be submitted to the cluster after the cluster has been deployed.

A basic Flink session cluster deployment in Kubernetes has three components:

  • a Deployment/Job which runs the JobManager
  • a Deployment for a pool of TaskManagers
  • a Service exposing the JobManager’s REST and UI ports

Using the resource definitions for a session cluster, launch the cluster with the kubectl command:

kubectl create -f flink-configuration-configmap.yaml
kubectl create -f jobmanager-service.yaml
kubectl create -f jobmanager-deployment.yaml
kubectl create -f taskmanager-deployment.yaml

Note that you could define your own customized options of flink-conf.yaml within flink-configuration-configmap.yaml.

You can then access the Flink UI via different ways:

./bin/flink run -m localhost:8081 ./examples/streaming/WordCount.jar
  • Create a NodePort service on the rest service of jobmanager:
    1. Run kubectl create -f jobmanager-rest-service.yaml to create the NodePort service on jobmanager. The example of jobmanager-rest-service.yaml can be found in appendix.
    2. Run kubectl get svc flink-jobmanager-rest to know the node-port of this service and navigate to http://<public-node-ip>:<node-port> in your browser.
    3. Similarly to port-forward solution, you could also use the following command below to submit jobs to the cluster:
./bin/flink run -m <public-node-ip>:<node-port> ./examples/streaming/WordCount.jar

In order to terminate the Flink session cluster, use kubectl:

kubectl delete -f jobmanager-deployment.yaml
kubectl delete -f taskmanager-deployment.yaml
kubectl delete -f jobmanager-service.yaml
kubectl delete -f flink-configuration-configmap.yaml

A Flink job cluster is a dedicated cluster which runs a single job. The job is part of the image and, thus, there is no extra job submission needed.

Creating the job-specific image

The Flink job cluster image needs to contain the user code jars of the job for which the cluster is started. Therefore, one needs to build a dedicated container image for every job. Please follow these instructions to build the Docker image.

In order to deploy the a job cluster on Kubernetes please follow these instructions.

Advanced Cluster Deployment

An early version of a Flink Helm chart is available on GitHub.

Appendix

Session cluster resource definitions

The Deployment definitions use the pre-built image flink:latest which can be found on Docker Hub. The image is built from this Github repository.

flink-configuration-configmap.yaml

apiVersion: v1
kind: ConfigMap
metadata:
  name: flink-config
  labels:
    app: flink
data:
  flink-conf.yaml: |+
    jobmanager.rpc.address: flink-jobmanager
    taskmanager.numberOfTaskSlots: 1
    blob.server.port: 6124
    jobmanager.rpc.port: 6123
    taskmanager.rpc.port: 6122
    jobmanager.heap.size: 1024m
    taskmanager.heap.size: 1024m
  log4j.properties: |+
    log4j.rootLogger=INFO, file
    log4j.logger.akka=INFO
    log4j.logger.org.apache.kafka=INFO
    log4j.logger.org.apache.hadoop=INFO
    log4j.logger.org.apache.zookeeper=INFO
    log4j.appender.file=org.apache.log4j.FileAppender
    log4j.appender.file.file=${log.file}
    log4j.appender.file.layout=org.apache.log4j.PatternLayout
    log4j.appender.file.layout.ConversionPattern=%d{yyyy-MM-dd HH:mm:ss,SSS} %-5p %-60c %x - %m%n
    log4j.logger.org.apache.flink.shaded.akka.org.jboss.netty.channel.DefaultChannelPipeline=ERROR, file

jobmanager-deployment.yaml

apiVersion: extensions/v1beta1
kind: Deployment
metadata:
  name: flink-jobmanager
spec:
  replicas: 1
  template:
    metadata:
      labels:
        app: flink
        component: jobmanager
    spec:
      containers:
      - name: jobmanager
        image: flink:latest
        workingDir: /opt/flink
        command: ["/bin/bash", "-c", "$FLINK_HOME/bin/jobmanager.sh start;\
          while :;
          do
            if [[ -f $(find log -name '*jobmanager*.log' -print -quit) ]];
              then tail -f -n +1 log/*jobmanager*.log;
            fi;
          done"]
        ports:
        - containerPort: 6123
          name: rpc
        - containerPort: 6124
          name: blob
        - containerPort: 8081
          name: ui
        livenessProbe:
          tcpSocket:
            port: 6123
          initialDelaySeconds: 30
          periodSeconds: 60
        volumeMounts:
        - name: flink-config-volume
          mountPath: /opt/flink/conf
      volumes:
      - name: flink-config-volume
        configMap:
          name: flink-config
          items:
          - key: flink-conf.yaml
            path: flink-conf.yaml
          - key: log4j.properties
            path: log4j.properties

taskmanager-deployment.yaml

apiVersion: extensions/v1beta1
kind: Deployment
metadata:
  name: flink-taskmanager
spec:
  replicas: 2
  template:
    metadata:
      labels:
        app: flink
        component: taskmanager
    spec:
      containers:
      - name: taskmanager
        image: flink:latest
        workingDir: /opt/flink
        command: ["/bin/bash", "-c", "$FLINK_HOME/bin/taskmanager.sh start; \
          while :;
          do
            if [[ -f $(find log -name '*taskmanager*.log' -print -quit) ]];
              then tail -f -n +1 log/*taskmanager*.log;
            fi;
          done"]
        ports:
        - containerPort: 6122
          name: rpc
        livenessProbe:
          tcpSocket:
            port: 6122
          initialDelaySeconds: 30
          periodSeconds: 60
        volumeMounts:
        - name: flink-config-volume
          mountPath: /opt/flink/conf/
      volumes:
      - name: flink-config-volume
        configMap:
          name: flink-config
          items:
          - key: flink-conf.yaml
            path: flink-conf.yaml
          - key: log4j.properties
            path: log4j.properties

jobmanager-service.yaml

apiVersion: v1
kind: Service
metadata:
  name: flink-jobmanager
spec:
  type: ClusterIP
  ports:
  - name: rpc
    port: 6123
  - name: blob
    port: 6124
  - name: ui
    port: 8081
  selector:
    app: flink
    component: jobmanager

jobmanager-rest-service.yaml. Optional service, that exposes the jobmanager rest port as public Kubernetes node’s port.

apiVersion: v1
kind: Service
metadata:
  name: flink-jobmanager-rest
spec:
  type: NodePort
  ports:
  - name: rest
    port: 8081
    targetPort: 8081
  selector:
    app: flink
    component: jobmanager

Back to top