Skip to content

Default Parameters

This example shows script function default parameters.

Script functions parameters mirror Python’s behaviour:

  • use the caller argument value if provided
  • otherwise use the default if provided
  • otherwise error as no value provided (and a value is always required in Argo Workflows)
 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20
from hera.workflows import DAG, Workflow, script


@script()
def generator():
    print("Another message for the world!")


@script()
def consumer(message: str = "Hello, world!", foo: int = 42):
    print(message)
    print(foo)


with Workflow(generate_name="default-param-overwrite-", entrypoint="d") as w:
    with DAG(name="d"):
        g = generator()
        c_default = consumer(name="consume-default")
        c_arg = consumer(name="consume-argument", arguments={"message": g.result})
        g >> [c_default, c_arg]

 1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
apiVersion: argoproj.io/v1alpha1
kind: Workflow
metadata:
  generateName: default-param-overwrite-
spec:
  entrypoint: d
  templates:
  - name: d
    dag:
      tasks:
      - name: generator
        template: generator
      - name: consume-default
        depends: generator
        template: consumer
      - name: consume-argument
        depends: generator
        template: consumer
        arguments:
          parameters:
          - name: message
            value: '{{tasks.generator.outputs.result}}'
  - name: generator
    script:
      image: python:3.10
      source: |-
        import os
        import sys
        sys.path.append(os.getcwd())
        print('Another message for the world!')
      command:
      - python
  - name: consumer
    inputs:
      parameters:
      - name: message
        default: Hello, world!
      - name: foo
        default: '42'
    script:
      image: python:3.10
      source: |-
        import os
        import sys
        sys.path.append(os.getcwd())
        import json
        try: foo = json.loads(r'''{{inputs.parameters.foo}}''')
        except: foo = r'''{{inputs.parameters.foo}}'''
        try: message = json.loads(r'''{{inputs.parameters.message}}''')
        except: message = r'''{{inputs.parameters.message}}'''

        print(message)
        print(foo)
      command:
      - python

Comments