Pass no argument to action command instead of passing empty values

[davidferlay]

Observed

• See action example defined here: https://github.com/launchrctl/launchr/blob/main/example/actions/arguments/action.yaml

➜  launchr git:(main) pl example:arguments
Image "envvars:latest" exists locally

Total number of arguments passed to the script: 2
- Argument 1: ""
- Argument 2: false

• When executing action with options, these options are passed to command as arguments

  command:
    - sh
    - /action/main.sh
    - "{{ .firstoption }}"
    - "{{ .secondoption }}"

• Meaning that their default/empty value is passed to command executed in container even if options are not passed

Expected

• Would be great that no option vlaue is passed to command executed in container when no option is used

➜  launchr git:(main) pl example:arguments
Image "envvars:latest" exists locally

Total number of arguments passed to the script: 0

[lexbritvin]

Considering the latest changes in Arguments and Options, it is now possible to not define "default" for both.

    - name: firstoption
      title: First option
      type: string
    - name: secondoption
      title: Second option
      description: Option to do something
      type: boolean
      default: false

There is no default value for firstoption and it's not required and variable in the template may be string|nil.
There is a default value for secondoption, will be false if not defined. If remove default, possible values may be true|false|nil in templates.

That allows us to make extra validation in actions.

  command:
    - sh
    - /action/main.sh
    - "{{ .firstoption | removeLineIfNil }}"
    - "{{ if not (isNil .secondoption) }}--secondoption={{ .secondoption }}{{ else }}{{ removeLine }}{{ end }}"

New template functions here .Arg | removeLineIfNil - template piping. It will process the template and remove the line if the given value is Nil.
if not (isNil .secondoption) - template condition to only check the value. May be helpful to pass flags as --secondoption={{ .secondoption }}
{{ removeLine }} - removes current line. Useful in condition result like we have in {{ else }}

Please, tell me if you like the naming, and it's clear for you.