inner templates context

[eddycharly]

Is it possible to pass a context to an inner template ?

My use case is like this :

{{ if .Environment.Values.ingress.alb }}
{{ range $ingress := .Values.ingress.alb }}
  - name: alb-{{ $ingress.class }}
    namespace: ingress
    chart: incubator/aws-alb-ingress-controller
    values:
      - templates/ingress/alb.yaml.gotmpl
{{ end }}
{{ end }}

In alb.yaml.gotmpl i have :

scope:
  ingressClass: {{ $ingress.class }}

So i need to access $ingress, that is, the current element that is processed in the main helmfile.yaml file.

[eddycharly]

@mumoshu do you have any advice for such use case please ?

[mumoshu]

Nope! It isn't possible. We're discussing about a potential feature to allow you to pass arbitrary context to templates in #745. See templateFile mentioned in #745 (comment) to see how it would work.

[eddycharly]

@mumoshu thanks for clarifying it out.
Why not introduce a tpl function like in helm ?

[mumoshu]

@eddycharly Adding tpl is ok. I thought we already have the issue for that. But How tpl helps in your use-case?

[eddycharly]

@mumoshu i could write something like :

{{ if .Environment.Values.ingress.alb }}
{{ range $ingress := .Values.ingress.alb }}
  - name: alb-{{ $ingress.class }}
    namespace: ingress
    chart: incubator/aws-alb-ingress-controller
    values:
      - {{ tpl (readFile "templates/ingress/alb.yaml.gotmpl") $ingress | fromYaml }}
{{ end }}
{{ end }}

This way i can control the inner template processing and context.

[mumoshu]

Ah that makes sense! You need indent but yeah it should generally work.

    values:
      -
{{ tpl (readFile "templates/ingress/alb.yaml.gotmpl") $ingress | fromYaml | indent 8}}

[mumoshu]

Ah, see #504 - It seems like we already have tpl :)

[eddycharly]

Not sure if i need to indent as it is manipulating objects but even if we need to specify the correct indent that's not a big deal, we do this with helm all the time.
I think it gives a lot of power to let the end user control templating programmatically rather than declaratively.

[mumoshu]

Not sure if i need to indent as it is manipulating objects

It is manipulating objects to be rendered as text. Please note that Helmfile templates are rendered before loading helmfile.yaml as YAML.

[mumoshu]

I think it gives a lot of power to let the end user control templating programmatically rather than declaratively.

Makes sense :)

As we already have tpl implemented. Would you mind trying what you've described? I appreciate any feedback if it doesn't work as expected.

[eddycharly]

I'm testing it right now, it seems to be working, i just need to make an additionnal test to ensure it's working the same way as in helm and come back to you.

[eddycharly]

@mumoshu it's almost working ;)
The case that doesn't work (and i believe it works in helm) is this one :

autoDiscoverAwsRegion: true
autoDiscoverAwsVpcID: true
clusterName: {{ $.Values.clusterName }}
nodeSelector:
  kops.k8s.io/instancegroup: infra
scope:
  ingressClass: {{ .class }}

In the inner template, we should be able to refer to the root context by prefixing the accessor with $ as in clusterName: {{ $.Values.clusterName }}.

The ingressClass: {{ .class }} part is working as expected, it is using the context that is passed to the tpl function, but the root context seems to be unavailable.

[mumoshu]

@eddycharly Can you try {{ tpl (readFile "templates/ingress/alb.yaml.gotmpl") (merge .Values $ingress)}} so that {{ .Values.clusterName }} would work?

And based on my knowledge about how tpl is implemented in helm and helmfile, I can't figure out how it can work in helm but helmfile. If you have any insight on that I'd appreciate your help.

[eddycharly]

@mumoshu I looked through the helm source code and i don't see anyting related to the root context i was talking about, i guess i was wrong.
I'll go with the tpl + indent solution, thank you for your patience ! :)

[eddycharly]

I close this issue, all is clear and already implemented.