Conditionals¶
We also support conditional execution. The syntax is implemented by govaluate
which offers the support for complex syntax. See in the example:
apiVersion: argoproj.io/v1alpha1
kind: Workflow
metadata:
generateName: coinflip-
spec:
entrypoint: coinflip
templates:
- name: coinflip
steps:
# flip a coin
- - name: flip-coin
template: flip-coin
# evaluate the result in parallel
- - name: heads
template: heads # call heads template if "heads"
when: "{{steps.flip-coin.outputs.result}} == heads"
- name: tails
template: tails # call tails template if "tails"
when: "{{steps.flip-coin.outputs.result}} == tails"
- - name: flip-again
template: flip-coin
- - name: complex-condition
template: heads-tails-or-twice-tails
# call heads template if first flip was "heads" and second was "tails" OR both were "tails"
when: >-
( {{steps.flip-coin.outputs.result}} == heads &&
{{steps.flip-again.outputs.result}} == tails
) ||
( {{steps.flip-coin.outputs.result}} == tails &&
{{steps.flip-again.outputs.result}} == tails )
- name: heads-regex
template: heads # call heads template if ~ "hea"
when: "{{steps.flip-again.outputs.result}} =~ hea"
- name: tails-regex
template: tails # call heads template if ~ "tai"
when: "{{steps.flip-again.outputs.result}} =~ tai"
# Return heads or tails based on a random number
- name: flip-coin
script:
image: python:alpine3.6
command: [python]
source: |
import random
result = "heads" if random.randint(0,1) == 0 else "tails"
print(result)
- name: heads
container:
image: alpine:3.6
command: [sh, -c]
args: ["echo \"it was heads\""]
- name: tails
container:
image: alpine:3.6
command: [sh, -c]
args: ["echo \"it was tails\""]
- name: heads-tails-or-twice-tails
container:
image: alpine:3.6
command: [sh, -c]
args: ["echo \"it was heads the first flip and tails the second. Or it was two times tails.\""]
Nested Quotes
If the parameter value contains quotes, it may invalidate the govaluate
expression.
To handle parameters with quotes, embed an expr
expression in the conditional.
For example:
when: "{{=inputs.parameters['may-contain-quotes'] == 'example'}}"