DocsConcepts and ExpressionsTask RunnersTask Runner TypesKubernetes Task Runner

Kubernetes Task Runner​Kubernetes ​Task ​Runner

Available on: Enterprise Edition>= 0.18.0

Run tasks as Kubernetes pods.

How to use the Kubernetes task runner

Thr Kubernetes task runner executes tasks in a specified Kubernetes cluster. It is useful to declare resource limits and resource requests.

Here is an example of a workflow with a task running Shell commands in a Kubernetes pod:

yaml
id: kubernetes_task_runner
namespace: company.team

description: |
  To get the kubeconfig file, run: `kubectl config view --minify --flatten`.
  Then, copy the values to the configuration below.
  Here is how Kubernetes task runner properties (on the left) map to the kubeconfig file's properties (on the right):
  - clientKeyData: client-key-data
  - clientCertData: client-certificate-data
  - caCertData: certificate-authority-data
  - masterUrl: server e.g. https://docker-for-desktop:6443
  - username: user e.g. docker-desktop

inputs:
  - id: file
    type: FILE

tasks:
  - id: shell
    type: io.kestra.plugin.scripts.shell.Commands
    inputFiles:
      data.txt: "{{ inputs.file }}"
    outputFiles:
      - "*.txt"
    containerImage: centos
    taskRunner:
      type: io.kestra.plugin.ee.kubernetes.runner.Kubernetes
    commands:
      - echo "Hello from a Kubernetes task runner!"
      - cp data.txt out.txt

File handling

If your script task has inputFiles or namespaceFiles configured, an init container will be added to upload files into the main container.

Similarly, if your script task has outputFiles configured, a sidecar container will be added to download files from the main container.

All containers will use an in-memory emptyDir volume for file exchange.

Failure scenarios

If a task is resubmitted (e.g. due to a retry or a Worker crash), the new Worker will reattach to the already running (or an already finished) pod instead of starting a new one.

Specifying resource requests for Python scripts

Some Python scripts may require more resources than others. You can specify the resources required by the Python script in the resources property of the task runner.

yaml
id: kubernetes_resources
namespace: company.team

tasks:
  - id: python_script
    type: io.kestra.plugin.scripts.python.Script
    containerImage: ghcr.io/kestra-io/pydata:latest
    taskRunner:
      type: io.kestra.plugin.ee.kubernetes.runner.Kubernetes
      namespace: default
      pullPolicy: Always
      config:
        username: docker-desktop
        masterUrl: https://docker-for-desktop:6443
        caCertData: xxx
        clientCertData: xxx
        clientKeyData: xxx
      resources:
        request: # The resources the container is guaranteed to get
          cpu: "500m" # Request 1/2 of a CPU (500 milliCPU)
          memory: "128Mi" # Request 128 MB of memory
    outputFiles:
      - "*.json"
    script: |
      import platform
      import socket
      import sys
      import json
      from kestra import Kestra

      print("Hello from a Kubernetes runner!")

      host = platform.node()
      py_version = platform.python_version()
      platform = platform.platform()
      os_arch = f"{sys.platform}/{platform.machine()}"


      def print_environment_info():
          print(f"Host's network name: {host}")
          print(f"Python version: {py_version}")
          print(f"Platform info: {platform}")
          print(f"OS/Arch: {os_arch}")

          env_info = {
              "host": host,
              "platform": platform,
              "os_arch": os_arch,
              "python_version": py_version,
          }
          Kestra.outputs(env_info)

          filename = "environment_info.json"
          with open(filename, "w") as json_file:
              json.dump(env_info, json_file, indent=4)


      if __name__ == '__main__':
          print_environment_info()

Using plugin defaults to avoid repetition

You can use pluginDefaults to avoid repeating the same configuration across multiple tasks. For example, you can set the pullPolicy to Always for all tasks in a namespace:

yaml
id: k8s_taskrunner
namespace: company.team

tasks:
  - id: parallel
    type: io.kestra.plugin.core.flow.Parallel
    tasks:
      - id: run_command
        type: io.kestra.plugin.scripts.python.Commands
        containerImage: ghcr.io/kestra-io/kestrapy:latest
        commands:
          - pip show kestra

      - id: run_python
        type: io.kestra.plugin.scripts.python.Script
        containerImage: ghcr.io/kestra-io/pydata:latest
        script: |
          import socket

          ip_address = socket.gethostbyname(hostname)
          print("Hello from AWS EKS and kestra!")
          print(f"Host IP Address: {ip_address}")

pluginDefaults:
  - type: io.kestra.plugin.scripts.python
    forced: true
    values:
      taskRunner:
        type: io.kestra.plugin.ee.kubernetes.runner.Kubernetes
        namespace: default
        pullPolicy: Always
        config:
          username: docker-desktop
          masterUrl: https://docker-for-desktop:6443
          caCertData: |-
            placeholder
          clientCertData: |-
            placeholder
          clientKeyData: |-
            placeholder

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