Invoking an argo workflow container with optional flags? - argo-workflows

Question

Say I have a dockerized command that can take an optional flag, similar to how ls can take a flag -l.
How can I make argo invoke it properly, allowing the caller to choose whether to include the flag or not?
This does not work, but hopefully it is somewhat close and demonstrates my intent:
apiVersion: argoproj.io/v1alpha1
kind: Workflow
metadata:
generateName: do-work-
spec:
arguments:
parameters:
- name: long-format
value: false
entrypoint: do-work
templates:
- name: do-work
container:
image: alpine:3.7
command: [ls]
args:
- "{{workflow.parameters.long-format == 'true' ? '-l' : '' }}"
- /etc
If I invoke it like argo submit do-work.yaml or argo submit do-work.yaml -p long-format=false then I want it to run ls /etc.
If I invoke it like argo submit do-work.yaml -p long-format=true then I want it to run ls -l /etc.

Answer 1

I figured out that something like this can work, using python to jam them all together into one string... kind of ugly.
apiVersion: argoproj.io/v1alpha1
kind: Workflow
metadata:
generateName: do-work-
spec:
arguments:
parameters:
- name: dir
value: /etc
- name: long-format
value: false
entrypoint: main
templates:
- name: main
dag:
tasks:
- name: build-cli-args
template: build-cli-args
- name: do-work
depends: build-cli-args
template: do-work
arguments:
parameters:
- name: cli-args
value: '{{tasks.build-cli-args.outputs.result}}'
- name: build-cli-args
script:
image: python:alpine3.6
command: [python]
source: |
cli_args = [
"-l" if "{{workflow.parameters.long-format}}" == "true" else None,
"{{workflow.parameters.dir}}",
]
print(" ".join([a for a in cli_args if a is not None]))
- name: do-work
inputs:
parameters:
- name: cli-args
script:
image: alpine:3.7
command: [sh, -ex]
source: |
ls {{inputs.parameters.cli-args}}
I will leave the question open in case someone can tell me how to do it more minimally, with an expression like I was attempting.