[helm chart] Allow passing template values for clusterName, region and vpcId

[adriananeci]

Issue

Helm doesn't support currently passing user parameters of the parent chart to the subchart (without using global)
See helm/helm#6699 and helm/helm#6876 for more context

Description of changes

While using the aws-load-balancer-controller as a dependency for another chart , I found it difficult to pass a global or a dynamic value for the clusterName, vpcId, region and other fields.

This PR adds support for passing a template as value for the clusterName, vpcId and region field.

Initial PR was raised in aws/eks-charts#911

Checklist

• Added/modified documentation as required (such as the README.md for modified charts)
• Incremented the chart version in Chart.yaml for the modified chart(s)
• Manually tested. Describe what testing was done in the testing section below
• Make sure the title of the PR is a good description that can go into the release notes

Testing

I've tested it by passing both static value and dynamic ones as follow:

• for static values, nothing has changed, e.g.

  • values.yaml :

  clusterName: "aa"
  

  • helm template --debug .

  ..............
   containers:
        - name: aws-load-balancer-controller
          args:
          - --cluster-name=aa
          - --ingress-class=alb
          command:
          - /controller
  ..............
  

• for template value:

  • values.yaml:

  ........
  clusterName: "{{- .Values.global.clusterName }}"
  ........
  

  • helm template --debug --set global.clusterName=ethos000-sbx-va6 .

  ..............
  containers:
      - name: aws-load-balancer-controller
        args:
        - --cluster-name=ethos000-sbx-va6
        - --ingress-class=alb
        command:
        - /controller
  ..............
  

• for empty/unset clusterName value:

  • helm template --debug .

install.go:194: [debug] Original chart version: ""
install.go:211: [debug] CHART PATH: /test-chart

Error: execution error at (test-chart/charts/aws-load-balancer-controller/templates/deployment.yaml:61:28): Chart cannot be installed without a valid clusterName!
helm.go:84: [debug] execution error at (/test-chart/charts/aws-load-balancer-controller/templates/deployment.yaml:61:28): Chart cannot be installed without a valid clusterName!

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

[adriananeci]

Dependency Review / govulncheck (pull_request) PR check failure doesn't seem related to changes from this PR if I read the logs right

[adriananeci]

/assign @M00nF1sh

[shraddhabang]

/lgtm

[oliviassss]

Dependency Review / govulncheck (pull_request) PR check failure doesn't seem related to changes from this PR if I read the logs right

@adriananeci, correct, it's another issue we will address later. can you please address the comments so we can merge your PR?

[adriananeci]

Dependency Review / govulncheck (pull_request) PR check failure doesn't seem related to changes from this PR if I read the logs right

@adriananeci, correct, it's another issue we will address later. can you please address the comments so we can merge your PR?

Done

[oliviassss]

thanks for your contribution.

/lgtm
/approve

[k8s-ci-robot]

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