VolcanoJob

Introduction

VolcanoJob, referred to as vcjob, is a CRD object for Volcano. Different from a Kubernetes job, it provides more advanced features such as specified scheduler, minimum number of members, task definition, lifecycle management, specific queue, and specific priority. VolcanoJob is ideal for high performance computing scenarios such as machine learning, big data applications, and scientific computing.

Example

apiVersion: batch.volcano.sh/v1alpha1
kind: Job
metadata:
  name: test-job
spec:
  minAvailable: 3
  schedulerName: volcano
  priorityClassName: high-priority
  policies:
    - event: PodEvicted
      action: RestartJob
  plugins:
    ssh: []
    env: []
    svc: []
  maxRetry: 5
  queue: default
  volumes:
    - mountPath: "/myinput"
    - mountPath: "/myoutput"
      volumeClaimName: "testvolumeclaimname"
      volumeClaim:
        accessModes: [ "ReadWriteOnce" ]
        storageClassName: "my-storage-class"
        resources:
          requests:
            storage: 1Gi
  tasks:
    - replicas: 6
      name: "default-nginx"
      template:
        metadata:
          name: web
        spec:
          containers:
            - image: nginx
              imagePullPolicy: IfNotPresent
              name: nginx
              resources:
                requests:
                  cpu: "1"
          restartPolicy: OnFailure

Key Fields

schedulerName

schedulerName indicates the scheduler that will schedule the job. Currently, the value can be volcano or default-scheduler, with volcano` selected by default.

minAvailable

minAvailable represents the minimum number of running pods required to run the job. Only when the number of running pods is not less than minAvailable can the job be considered as running.

volumes

volumes indicates the configuration of the volume to which the job is mounted. It complies with the volume configuration requirements in Kubernetes.

tasks.replicas

tasks.replicas indicates the number of pod replicas in a task.

tasks.template

tasks.template defines the pod configuration of a task. It is the same as a pod template in Kubernetes.

tasks.policies

tasks.policies defines the lifecycle policy of a task.

policies

policies defines the default lifecycle policy for all tasks when tasks.policies is not set.

plugins

plugins indicates the plugins used by Volcano when the job is scheduled.

queue

queue indicates the queue to which the job belongs.

priorityClassName

priorityClassName indicates the priority of the job. It is used in preemptive scheduling.

maxRetry

maxRetry indicates the maximum number of retries allowed by the job.

Status

pending

pending indicates that the job is waiting to be scheduled.

aborting

aborting indicates that the job is being aborted because of some external factors.

aborted

aborted indicates that the job has already been aborted because of some external factors.

running

running indicates that there are at least minAvailable pods running.

restarting

restarting indicates that the job is restarting.

completing

completing indicates that there are at least minAvailable pods in the completing state. The job is doing cleanup.

completed

completed indicates that there are at least minAvailable pods in the completed state. The job has completed cleanup.

terminating

terminating indicates that the job is being terminated because of some internal factors. The job is waiting pods to release resources.

terminated

terminated indicates that the job has already been terminated because of some internal factors.

failed

failed indicates that the job still cannot start after maxRetry tries.

Usage

TensorFlow Workload

Create a TensorFlow workload with a ps and three workers.

apiVersion: batch.volcano.sh/v1alpha1
kind: Job
metadata:
  name: tensorflow-dist-mnist
spec:
  minAvailable: 3   // There must be at least 3 available pods.
  schedulerName: volcano    // Scheduler specified
  plugins:
    env: []
    svc: []
  policies: 
    - event: PodEvicted // Restart the job when a pod is evicted.
      action: RestartJob
  tasks:
    - replicas: 1   // One ps pod specified
      name: ps
      template: // Definition of the ps pod
        spec:
          containers:
            - command:
                - sh
                - -c
                - |
                  PS_HOST=`cat /etc/volcano/ps.host | sed 's/$/&:2222/g' | sed 's/^/"/;s/$/"/' | tr "\n" ","`;
                  WORKER_HOST=`cat /etc/volcano/worker.host | sed 's/$/&:2222/g' | sed 's/^/"/;s/$/"/' | tr "\n" ","`;
                  export TF_CONFIG={\"cluster\":{\"ps\":[${PS_HOST}],\"worker\":[${WORKER_HOST}]},\"task\":{\"type\":\"ps\",\"index\":${VK_TASK_INDEX}},\"environment\":\"cloud\"};
                  python /var/tf_dist_mnist/dist_mnist.py
              image: volcanosh/dist-mnist-tf-example:0.0.1
              name: tensorflow
              ports:
                - containerPort: 2222
                  name: tfjob-port
              resources: {}
          restartPolicy: Never
    - replicas: 2   // Two worker pods specified
      name: worker
      policies:
        - event: TaskCompleted  // The job will be marked as completed when two worker pods finish tasks.
          action: CompleteJob
      template: // Definition of worker pods
        spec:
          containers:
            - command:
                - sh
                - -c
                - |
                  PS_HOST=`cat /etc/volcano/ps.host | sed 's/$/&:2222/g' | sed 's/^/"/;s/$/"/' | tr "\n" ","`;
                  WORKER_HOST=`cat /etc/volcano/worker.host | sed 's/$/&:2222/g' | sed 's/^/"/;s/$/"/' | tr "\n" ","`;
                  export TF_CONFIG={\"cluster\":{\"ps\":[${PS_HOST}],\"worker\":[${WORKER_HOST}]},\"task\":{\"type\":\"worker\",\"index\":${VK_TASK_INDEX}},\"environment\":\"cloud\"};
                  python /var/tf_dist_mnist/dist_mnist.py
              image: volcanosh/dist-mnist-tf-example:0.0.1
              name: tensorflow
              ports:
                - containerPort: 2222
                  name: tfjob-port
              resources: {}
          restartPolicy: Never

Argo Workload

Create an argo workload with two pod replicas. The workload is considered normal when at least one pod replica works normally.

apiVersion: argoproj.io/v1alpha1
kind: Workflow
metadata:
  generateName: volcano-step-job-
spec:
  entrypoint: volcano-step-job
  serviceAccountName: argo
  templates:
  - name: volcano-step-job
    steps:
    - - name: hello-1
        template: hello-tmpl
        arguments:
          parameters: [{name: message, value: hello1}, {name: task, value: hello1}]
    - - name: hello-2a
        template: hello-tmpl
        arguments:
          parameters: [{name: message, value: hello2a}, {name: task, value: hello2a}]
      - name: hello-2b
        template: hello-tmpl
        arguments:
          parameters: [{name: message, value: hello2b}, {name: task, value: hello2b}]
  - name: hello-tmpl
    inputs:
      parameters:
      - name: message
      - name: task
    resource:
      action: create
      successCondition: status.state.phase = Completed
      failureCondition: status.state.phase = Failed
      manifest: |           // Definition of the VolcanoJob
        apiVersion: batch.volcano.sh/v1alpha1
        kind: Job
        metadata:
          generateName: step-job-{{inputs.parameters.task}}-
          ownerReferences:
          - apiVersion: argoproj.io/v1alpha1
            blockOwnerDeletion: true
            kind: Workflow
            name: "{{workflow.name}}"
            uid: "{{workflow.uid}}"
        spec:
          minAvailable: 1
          schedulerName: volcano
          policies:
          - event: PodEvicted
            action: RestartJob
          plugins:
            ssh: []
            env: []
            svc: []
          maxRetry: 1
          queue: default
          tasks:
          - replicas: 2
            name: "default-hello"
            template:
              metadata:
                name: helloworld
              spec:
                containers:
                - image: docker/whalesay
                  imagePullPolicy: IfNotPresent
                  command: [cowsay]
                  args: ["{{inputs.parameters.message}}"]
                  name: hello
                  resources:
                    requests:
                      cpu: "100m"
                restartPolicy: OnFailure

MindSpore Workload

Create a MindSpore workload with eight pod replicas. The workload is considered normal when at least one pod replica works normally.

apiVersion: batch.volcano.sh/v1alpha1
kind: Job
metadata:
  name: mindspore-cpu
spec:
  minAvailable: 1
  schedulerName: volcano
  policies:
    - event: PodEvicted
      action: RestartJob
  plugins:
    ssh: []
    env: []
    svc: []
  maxRetry: 5
  queue: default
  tasks:
    - replicas: 8
      name: "pod"
      template:
        spec:
          containers:
            - command: ["/bin/bash", "-c", "python /tmp/lenet.py"]
              image: lyd911/mindspore-cpu-example:0.2.0
              imagePullPolicy: IfNotPresent
              name: mindspore-cpu-job
              resources:
                limits:
                  cpu: "1"
                requests:
                  cpu: "1"
          restartPolicy: OnFailure

Note

Supported Frameworks

Volcano supports almost all mainstream computing frameworks including:

1. Spark
2. TensorFlow
3. PyTorch
4. Flink
5. Argo
6. MindSpore
7. PaddlePaddle
8. Open MPI
9. Horovod
10. MXNet
11. Kubeflow
12. KubeGene
13. Cromwell

volcano or default-scheduler

Volcano has been enhanced in batch computing when compared with default-scheduler. It is ideal for high performance computing scenarios such as machine learning, big data applications, and scientific computing.