How to return a default false if a property dont exists in values.yaml file?

yaml file . i have a value as below defined under global

global:
  logging:
    log4j:
     enabled: true

I am also have a helper function

{{- define "helm-basic-template.logging-enabled" -}}
{{ .Values.global.logging.log4j.enabled | default "false" }}
{{- end -}}

it is possible the property global.logging.log4j.enabled may not exist , in that case i expect the helper function to return false, otherwise return the value of the property . however it is not working as i expected . any idea what is wrong with my function ? or any other better way to re write it ? thank you

Solution

To avoid variables being undefined, additional checks are needed here.

According to the helm document, when the object is empty, the if statement judges to return false.

A pipeline is evaluated as false if the value is:

a boolean false
a numeric zero
an empty string
a nil (empty or null)
an empty collection (map, slice, tuple, dict, array)

Use the following checks directly.

{{- if .Values.global }}
{{- if .Values.global.logging }}
{{- if .Values.global.logging.log4j }}
{{- if .Values.global.logging.log4j.enabled }}
apiVersion: v1
kind: ConfigMap
metadata:
  name: logging-cm
data:
  conf.json: |
    xxxxx
...
{{- end }}
{{- end }}
{{- end }}
{{- end }}

Or employ a named template approach.

{{- define "helm-basic-template.logging-enabled" -}}
{{- $val := false }}
{{- if .Values.global -}}
{{- if .Values.global.logging -}}
{{- if .Values.global.logging.log4j -}}
{{- if .Values.global.logging.log4j.enabled -}}
{{- $val = true }}
{{- end -}}
{{- end -}}
{{- end -}}
{{- end -}}
{{ $val }}
{{- end -}}

Or use default to set a simple default value.

{{- define "helm-basic-template.logging-enabled" -}}
{{- .Values.global.logging.log4j.enabled | default false .Values.global.logging.log4j.enabled -}}
{{- end -}}

Or use dig to select keys from a list of values.

{{- define "helm-basic-template.logging-enabled" -}}
{{- dig "logging" "log4j" "enabled" false .Values.global -}}
{{- end -}}