Kubernetes Setup

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 jobmanager-service.yaml
kubectl create -f jobmanager-deployment.yaml
kubectl create -f taskmanager-deployment.yaml

You can then access the Flink UI via kubectl proxy:

  1. Run kubectl proxy in a terminal
  2. Navigate to http://localhost:8001/api/v1/namespaces/default/services/flink-jobmanager:ui/proxy in your browser

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

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.

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
        args:
        - jobmanager
        ports:
        - containerPort: 6123
          name: rpc
        - containerPort: 6124
          name: blob
        - containerPort: 6125
          name: query
        - containerPort: 8081
          name: ui
        env:
        - name: JOB_MANAGER_RPC_ADDRESS
          value: flink-jobmanager

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
        args:
        - taskmanager
        ports:
        - containerPort: 6121
          name: data
        - containerPort: 6122
          name: rpc
        - containerPort: 6125
          name: query
        env:
        - name: JOB_MANAGER_RPC_ADDRESS
          value: flink-jobmanager

jobmanager-service.yaml

apiVersion: v1
kind: Service
metadata:
  name: flink-jobmanager
spec:
  ports:
  - name: rpc
    port: 6123
  - name: blob
    port: 6124
  - name: query
    port: 6125
  - name: ui
    port: 8081
  selector:
    app: flink
    component: jobmanager

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