doc: Update documentation about layering release values

[a-hat]

setTemplate and valuesTemplate do not work, I think it is correct without the Template suffix.

I also added a note to the documentation regarding this issue #836

[mumoshu]

@a-hat Hey! Thanks for your support.

This part of the documentation specifically explain how Release Templating works. Are you sure you've tested it with the Release Template feature, or just regular values without nested template expressions in it?

[mumoshu]

The point is that this shouldn't work as expected until #823:

    set:
    - name: '{{`{{ .Release.Name }}`}}'
      values: '{{`{{ .Release.Namespace }}`}}'

As until #823 nested template expressions that are starting with:

{{`

and ending with:

`}}

are rendered as-is without template expressions being evaluated.

[a-hat]

Hi @mumoshu!

After reading the documentation I tried something like this (note the valuesTemplate in the templates map) to set values in a release template:

templates:
  default: &default
    valuesTemplate:
    - image: default    

releases:
- name: demo
  <<: *default
  chart: stable/traefik
  version: ^1.70.2
  values:
  - image: demo

which gives me these errors:

in ./helmfile.yaml: failed to read helmfile.yaml: reading document at index 1: yaml: unmarshal errors:
  line 3: field valuesTemplate not found in type state.TemplateSpec
  line 3: field valuesTemplate not found in type state.ReleaseSpec

Is the documentation referring to something else which I am missing?

[mumoshu]

@a-hat valuesTemplate should be available since helmfile v0.82.0! Which version of helmfile are you using?

Btw, in your example you don't need valuesTemplate. Just use values.

templates:
  default: &default
    values:
    - image: default    

releases:
- name: demo
  <<: *default
  chart: stable/traefik
  version: ^1.70.2
  values:
  - image: demo

[a-hat]

I see, thanks for the clarification. I was using version 0.81.3, so this is why valuesTemplate did not work.

I updated the PR and left the section about layering values. Does this make sense for you?

[mumoshu]

@a-hat Thanks!

Would you mind prepending ## Layering Release Values to the paragraph you've just added?

The statements are correct. I believe it should reside within a dedicated section though.

[a-hat]

Thanks for your feedback! Makes sense, I have updated the doc.

[mumoshu]

LGTM. Thanks a lot for your contribution @a-hat ☺️