Kubernetes

INFO

LakeSail offers flexible enterprise support options, including managing Sail on Kubernetes.

Get in touch to learn more.

Sail supports distributed data processing on Kubernetes clusters. This guide demonstrates how to deploy Sail on a Kubernetes cluster and connect to it via Spark Connect.

Building the Docker Image

We first need to build the Docker image for Sail. Please refer to the Docker Images Guide for more information.

Loading the Docker Image

You will need to make the Docker image available to your Kubernetes cluster. The exact steps depend on your Kubernetes environment. For example, you may want to push the Docker image to your private Docker registry accessible from the Kubernetes cluster.

If you are using a local Kubernetes cluster, you may need to load the Docker image into the cluster. The command varies depending on the Kubernetes distribution you are using. Here are the examples for some well-known Kubernetes distributions. You can refer to their documentation for more details.

kind

kind load docker-image sail:latest

minikube

minikube image load sail:latest

k3d

k3d image import sail:latest

k3s

docker save sail:latest | k3s ctr images import -

MicroK8s

docker save sail:latest | microk8s images import

The following sections use kind as an example, but you can run Sail in other Kubernetes distributions of your choice. Run the following command to create a local Kubernetes cluster.

kind create cluster

Then load the Docker image into the cluster.

kind load docker-image sail:latest

Running the Sail Server

INFO

The way to configure Sail applications is not stable yet. Please refer to the Changelog if the configuration ever changes in future releases.

Create a file named sail.yaml with the following content.

sail.yaml

apiVersion: v1
kind: Namespace
metadata:
  name: sail
---
apiVersion: apps/v1
kind: Deployment
metadata:
  name: sail-spark-server
  namespace: sail
  labels:
    app.kubernetes.io/name: sail
    app.kubernetes.io/component: spark-server
spec:
  # We cannot have more than one replica because each Spark session is tied to a single pod.
  replicas: 1
  selector:
    matchLabels:
      app.kubernetes.io/name: sail
      app.kubernetes.io/component: spark-server
  template:
    metadata:
      labels:
        app.kubernetes.io/name: sail
        app.kubernetes.io/component: spark-server
    spec:
      serviceAccountName: sail-user
      containers:
        - name: server
          image: sail:latest
          command: [ "sail" ]
          args: [ "spark", "server", "--port", "50051" ]
          ports:
            - containerPort: 50051
          imagePullPolicy: IfNotPresent
          env:
            - name: RUST_LOG
              value: info
            - name: SAIL_MODE
              value: "kubernetes-cluster"
            - name: SAIL_CLUSTER__DRIVER_LISTEN_HOST
              value: "0.0.0.0"
            - name: SAIL_CLUSTER__DRIVER_EXTERNAL_HOST
              valueFrom:
                fieldRef:
                  fieldPath: status.podIP
            - name: SAIL_KUBERNETES__IMAGE
              value: sail:latest
            - name: SAIL_KUBERNETES__NAMESPACE
              value: sail
            - name: SAIL_KUBERNETES__DRIVER_POD_NAME
              valueFrom:
                fieldRef:
                  fieldPath: metadata.name
---
apiVersion: v1
kind: Service
metadata:
  name: sail-spark-server
  namespace: sail
  labels:
    app.kubernetes.io/name: sail
    app.kubernetes.io/component: spark-server
spec:
  selector:
    app.kubernetes.io/name: sail
    app.kubernetes.io/component: spark-server
  ports:
    - protocol: TCP
      port: 50051
      targetPort: 50051
---
apiVersion: rbac.authorization.k8s.io/v1
kind: Role
metadata:
  name: sail-spark-server
  namespace: sail
rules:
  - apiGroups: [ "" ]
    resources: [ "pods" ]
    verbs: [ "*" ]
---
apiVersion: v1
kind: ServiceAccount
metadata:
  name: sail-user
  namespace: sail
---
apiVersion: rbac.authorization.k8s.io/v1
kind: RoleBinding
metadata:
  name: sail-spark-server
  namespace: sail
subjects:
  - kind: ServiceAccount
    name: sail-user
    namespace: sail
roleRef:
  kind: Role
  name: sail-spark-server
  apiGroup: rbac.authorization.k8s.io

Create the Kubernetes resources using the following command. The Sail Spark Connect server runs as a Kubernetes deployment, and the gRPC port is exposed as a Kubernetes service.

kubectl apply -f sail.yaml

Running Spark Jobs

To connect to the Sail Spark Connect server, you can forward the service port to your local machine.

kubectl -n sail port-forward service/sail-spark-server 50051:50051

Now you can run Spark jobs using the standalone Spark client. Here is an example of running PySpark shell powered by Sail on Kubernetes. Sail worker pods are launched on-demand to execute Spark jobs. The worker pods are terminated after a certain period of inactivity.

env SPARK_CONNECT_MODE_ENABLED=1 SPARK_REMOTE="sc:https://localhost:50051" pyspark

Cleaning Up

Run the following command to clean up the Kubernetes resources for the Sail server. All Sail worker pods will be terminated automatically as well.

kubectl delete -f sail.yaml

You can delete the kind cluster using the following command.

kind delete cluster