parallelism-nested-workflow.yaml

# Example on specifying parallelism on the outer workflow and limiting the number of its
# children workflows to be run at the same time.
# 
# As the parallelism of A is 1, the four steps of seq-step will run sequentially.

apiVersion: argoproj.io/v1alpha1
kind: Workflow
metadata:
  generateName: parallelism-nested-workflow-
spec:
  arguments:
    parameters:
    - name: seq-list
      value: |
        ["a","b","c","d"]
  entrypoint: A
  templates:
  - name: A
    parallelism: 1
    inputs:
      parameters:
      - name: seq-list
    steps:
    - - name: seq-step
        template: B
        arguments:
          parameters:
          - name: seq-id
            value: "{{item}}"
        withParam: "{{inputs.parameters.seq-list}}"

  - name: B
    inputs:
      parameters:
      - name: seq-id
    steps:
    - - name: jobs
        template: one-job
        arguments:
          parameters:
          - name: seq-id
            value: "{{inputs.parameters.seq-id}}"
        withParam: "[1, 2]"

  - name: one-job
    inputs:
      parameters:
      - name: seq-id
    container:
      image: alpine
      command: ['/bin/sh', '-c']
      args: ["echo {{inputs.parameters.seq-id}}; sleep 30"]