[Helm][minor] Make "disabled" flag for worker groups optional

[kevin85421]

Why are these changes needed?

As mentioned by @tbabej in #537, an error will be reported if the disabled key on the default worker group is undefined. In old Helm versions, when disabled key is undefined, it will be set to nil. Hence, when we run the following command, it will report the error "incompatible types for comparison". Obviously, nil and boolean cannot be compared for equality. See helm/helm#6376 for more details.

$ helm lint    
==> Linting .
[ERROR] templates/: template: ray-cluster/templates/raycluster-cluster.yaml:105:9: executing "ray-cluster/templates/raycluster-cluster.yaml" at <ne .Values.worker.disabled true>: error calling ne: incompatible types for comparison

Error: 1 chart(s) linted, 1 chart(s) failed

In this PR, I give the disabled key a default value to make it become an optional field.

• Helm version v3.4.1 => can reproduce [Bug] Helm chart install fails due to undefined worker key in values.yml #537
• Helm version v3.9.4 => cannot reproduce [Bug] Helm chart install fails due to undefined worker key in values.yml #537

Related issue number

Closes #544
#499

Checks

$ git diff | cat         
diff --git a/helm-chart/ray-cluster/templates/raycluster-cluster.yaml b/helm-chart/ray-cluster/templates/raycluster-cluster.yaml
index 67922d4..5432068 100644
--- a/helm-chart/ray-cluster/templates/raycluster-cluster.yaml
+++ b/helm-chart/ray-cluster/templates/raycluster-cluster.yaml
@@ -102,7 +102,7 @@ spec:
 {{ include "ray-cluster.labels" $ | indent 10 }}
   {{- end }}
   {{- end }}
-  {{- if ne .Values.worker.disabled true }}
+  {{- if ne (.Values.worker.disabled | default false) true }}
   - rayStartParams:
     {{- range $key, $val := .Values.worker.initArgs }}
       {{ $key }}: {{ $val | quote }}
diff --git a/helm-chart/ray-cluster/values.yaml b/helm-chart/ray-cluster/values.yaml
index be80d86..a099a50 100644
--- a/helm-chart/ray-cluster/values.yaml
+++ b/helm-chart/ray-cluster/values.yaml
@@ -54,7 +54,7 @@ head:
 worker:
   # If you want to disable the default workergroup
   # change the line below
-  disabled: false
+  # disabled: false
   groupName: workergroup
   replicas: 1
   type: worker

$ helm lint     
==> Linting .

1 chart(s) linted, 0 chart(s) failed

• I've made sure the tests are passing.
• Testing Strategy
  • Unit tests
  • Manual tests
  • This PR is not tested :(

[kevin85421]

cc @DmitriGekhtman @tbabej

[DmitriGekhtman]

Thanks for the fix!
To finish this up, could you return values.yaml to its state prior to #543?
(That will make it clearer that the disabled field is optional.)

[kevin85421]

@DmitriGekhtman Thank you for your review! I have updated it.

[DmitriGekhtman]

Looks great, thank you!

[DmitriGekhtman]

Merging before CI finishes, as Helm charts aren't yet tested in CI.