How to pass dynamic arguments to a helm chart that runs a job

Question

I'd like to allow our developers to pass dynamic arguments to a helm template (Kubernetes job). Currently my arguments in the helm template are somewhat static (apart from certain values) and look like this

      Args:
        --arg1
        value1
        --arg2
        value2
        --sql-cmd
        select * from db

If I were run a task using the docker container without Kubernetes, I would pass parameters like so:

docker run my-image --arg1 value1 --arg2 value2 --sql-cmd "select * from db"

Is there any way to templatize arguments in a helm chart in such way that any number of arguments could be passed to a template.

For example.

cat values.yaml
...
arguments: --arg1 value1 --arg2 value2 --sql-cmd "select * from db"
...

or

cat values.yaml
...
arguments: --arg3 value3
...

I've tried a few approaches but was not successful. Here is one example:

     Args:          
      {{  range .Values.arguments }}
        {{ . }}
      {{ end }}

Answer 1

Yes. In values.yaml you need to give it an array instead of a space delimited string.

cat values.yaml
...
arguments: ['--arg3', 'value3', '--arg2', 'value2']
...

or

cat values.yaml
...
arguments:
- --arg3
- value3
- --arg2
- value2
...

and then you like you mentioned in the template should do it:

     args:          
      {{  range .Values.arguments }}
        - {{ . }}
      {{ end }}

If you want to override the arguments on the command line you can pass an array with --set like this:

--set arguments={--arg1, value1, --arg2, value2, --arg3, value3, ....}

Answer 2

In your values file define arguments as:

extraArgs:
  argument1: value1
  argument2: value2
  booleanArg1:

In your template do:

    args:
{{- range $key, $value := .Values.extraArgs }}
    {{- if $value }}
    - --{{ $key }}={{ $value }}
    {{- else }}
    - --{{ $key }}
    {{- end }}
{{- end }}

Answer 3

Rico's answer needed to be improved. Using the previous example I've received errors like:

templates/deployment.yaml: error converting YAML to JSON: yaml or

failed to get versionedObject: unable to convert unstructured object to apps/v1beta2, Kind=Deployment: cannot restore slice from string

This is my working setup with coma in elements: ( the vertical format for the list is more readable )

cat values.yaml
...
arguments: [
    "--arg3,", 
    "value3,",
    "--arg2,",
    "value2,",
]
...

in the template should do it:

          args: [
{{  range .Values.arguments }}
{{ . }}
{{ end }}
          ]