• Helm templates: Using fullname inside a range block

    2 min read

    helm template fullname range

    If we try to use the template fullname function inside a range block as follows:

    {{ range .Values.secrets }}
    ---
    apiVersion: 'kubernetes-client.io/v1'
    kind: ExternalSecret
    metadata:
      name: "{{ template "pet2cattle.fullname" . }}-{{ . | replace "_" "-" }}"
    (...)
    {{ end }}
    

    We will get a can't evaluate field Values in type string like follows:

    Error: template: pet2cattle/templates/_helpers.tpl:14:14: executing "pet2cattle.fullname" at <.Values.fullnameOverride>: can't evaluate field Values in type string
    

    29/12/2021

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  • Template complexity: can't evaluate field Values in type interface {}

    2 min read

    helm template error context range

    Working with templates can be challenging since, at the end of the day, we are mixing two languages: The template language and the language on which the template itself is written. Doing so we are getting the complexity of one language in addition of the complexity of the other language. That's maybe the main reason why, sometimes, it can be challenging to spot a issues when templates are involved. For example, helm uses templates for generating the appropriate Kubernetes objects, this is one of the errors you might encounter:

    $ helm template  . --debug 
    install.go:172: [debug] Original chart version: ""
    install.go:189: [debug] CHART PATH: /home/pet2cattle/git/spinnaker/helm-spinnaker
    
    
    Error: template: spinnaker/templates/hooks/install-using-hal.yaml:15:28: executing "spinnaker/templates/hooks/install-using-hal.yaml" at <include (print $.Template.BasePath "/configmap/halyard-config.yaml") .>: error calling include: template: spinnaker/templates/configmap/halyard-config.yaml:120:54: executing "spinnaker/templates/configmap/halyard-config.yaml" at <.Values.serviceAccount.spinnaker.enable>: can't evaluate field Values in type interface {}
    helm.go:81: [debug] template: spinnaker/templates/hooks/install-using-hal.yaml:15:28: executing "spinnaker/templates/hooks/install-using-hal.yaml" at <include (print $.Template.BasePath "/configmap/halyard-config.yaml") .>: error calling include: template: spinnaker/templates/configmap/halyard-config.yaml:120:54: executing "spinnaker/templates/configmap/halyard-config.yaml" at <.Values.serviceAccount.spinnaker.enable>: can't evaluate field Values in type interface {}
    

    The error itself looks challenging at first glance, the lines that causes this message are the following:

    {{- range $index, $context := .Values.kubeConfig.contexts }}
    (...)
        $HAL_COMMAND config provider kubernetes account $PROVIDER_COMMAND {{ $context }} --docker-registries dockerhub \
                    --context {{ $context }} {{ if .Values.serviceAccount.spinnaker.enable }}--service-account true{{ end }} \
    (...)
    {{- end }}
    

    Can you spot the mistake?

    02/04/2021

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From pet to cattle
Treat your kubernetes clusters like cattle, not pets