ingress.yaml template returns error in renderring --> nil pointer evaluating interface {}.service

Question

I am installing a helm chart which has a ingress.yaml template.

I get this error:

Error: render error in "chartmuseum/templates/ingress.yaml": template: chartmuseum/templates/ingress.yaml:35:22: executing "chartmuseum/templates/ingress.yaml" at <.Values.service.servicename>: nil pointer evaluating interface {}.service

I am not able to find where the problem is. The same set of if else structure works abolutely fine in the service.yaml of the same helm chart.

- path: {{ default "/" .path | quote }}
        backend:
        {{- if .Values.service.servicename }}
          serviceName: {{ .Values.service.servicename }}
        {{- else }}
          serviceName: {{ include "chartmuseum.fullname" . }}
        {{- end }}

Getting error on this line --> serviceName: {{ .Values.service.servicename }}

The code that works in service.yaml fine is

metadata:
{{- if .Values.service.servicename }}
  name: {{ .Values.service.servicename }}
{{- else }}
  name: {{ include "chartmuseum.fullname" . }}
{{- end }}

Expected result: if there is a servcice.servicename in values in values.yaml file , the ingress should pick the value from there for the key serviceName. Else it should include "chartmuseum.fullname".

The same structure works fine for service.yaml.

Below is the url of the original helm chart that i am using.

https://github.com/helm/charts/tree/master/stable/chartmuseum

I just modified the ingress.yaml to add if else block around line 31. Ingress.yaml https://github.com/helm/charts/blob/master/stable/chartmuseum/templates/ingress.yaml

Values.yaml file is insignificant. I have the below values in it

service:
  servicename: helm-charts-test

but even without this value, the if else block is expected to work.

Answer 1

What you're seeing is a weird caveat in Go templating. Your conditional logic is being evaluated inside a range loop. This means . you're using to access Values is not the one you expect it to be, as it's overridden for each range iteration evaluation. You can use $, which references the global scope in order to access the Values as expected.

For your scenario, it would be something like:

- path: {{ default "/" .path | quote }}
        backend:
        {{- if $.Values.service.servicename }}
          serviceName: {{ $.Values.service.servicename }}
        {{- else }}
          serviceName: {{ include "chartmuseum.fullname" $ }}
        {{- end }}

See here for more details.