fix: 🐛 annotations leaking between aliased subcharts

[romeuhcf]

What does this PR do?

When using multiple traefik setups as subcharts, this prevents annotations to be leaking from one alias to another.

Motivation

Relates to helm/helm#11891 .

Merge mutates its first parameter and this is not isolated between multiple aliased subcharts.

I have this Chart.yaml

apiVersion: v2
name: inf-traefik
description: A Helm chart for Kubernetes
type: application
version: 0.1.0
dependencies:
  - name: traefik
    version: ">0"
    repository: https://helm.traefik.io/traefik
    alias: traefik-external
  - name: traefik
    version: ">0"
    repository: https://helm.traefik.io/traefik
    alias: traefik-internal

And this values.yaml

traefik-external:
  ingressRoute:
    dashboard:
      annotations:
        kubernetes.io/ingress.class: traefik-ext

  service:
    annotations:
      external-dns.alpha.kubernetes.io/hostname: "*.lb-ext.alpha.example.com"


traefik-internal:
  ingressRoute:
    dashboard:
      annotations:
        kubernetes.io/ingress.class: traefik-int

  service:
    name: traefik-int
    annotations:
      external-dns.alpha.kubernetes.io/hostname: "*.lb-int.alpha.example.com"

When running template I would expect that each aliased subchart receives only its specific values.

❯ helm3 template . | grep hostname:
    external-dns.alpha.kubernetes.io/hostname: '*.lb-ext.alpha.example.com' # not an actual result
    external-dns.alpha.kubernetes.io/hostname: '*.lb-int.alpha.example.com'

But rendering the template, I get both services with same value.

❯ helm template . | grep hostname:
    external-dns.alpha.kubernetes.io/hostname: '*.lb-int.alpha.example.com'
    external-dns.alpha.kubernetes.io/hostname: '*.lb-int.alpha.example.com'

More

• Yes, I updated the tests accordingly
• Yes, I ran make test and all the tests passed

[mloiseleur]

Hello @romeuhcf,

Thanks for this PR. It looks good.

[project0]

can you add some tests for this? We have already something similar, but this case is not really covered.

[project0]

I understand testing is difficult in this case.
Just to make it clear: This is actually a workaround for a bug of the helm/spring merge function as it results into some cached values.