helm function to transform yaml to property-like format - kubernetes

Question

new to k8s, trying to remove stupid boilerplate and write better config-map.yaml generation. Expected format is:
...
data:
first.property: 1
second.property: 2
...
I don't want to refer there key by key to values.yaml, like:
...
data:
first.property: {{.Values.configuration.first.property}}
second.property: {{.Values.configuration.second.property}}
...
I want to include whole subtree into here, like:
{{ (toYaml .Values.configuration | indent 2) }}
That works, but (as expected) the yaml is inserted as is. I need to adapt it to property-like format. So the question is: is there a function/way in helm/go templates how to transform this yaml:
a:
b:
c: 1
d: 2
into following representation?
a.b.c: 1
a.b.d: 2

Answer 1

this based on answer How do you apply a recursive formatting with Go Templates (Helm)? in which I fixed some problems and the final solution could be:
{{- define "flattenYaml" -}}
{{- $dict := . -}}
{{- $prefix := $dict.prefix -}}
{{- $data := $dict.data -}}
{{- $knd := kindOf $data -}}
{{- if eq $knd "map" }}
{{- range (keys $data) }}
{{- $key := . }}
{{- $prefixedKey := (printf "%s.%s" $prefix $key) }}
{{- $value := get $data $key }}
{{- $valueKind := kindOf $value }}
{{- if eq $valueKind "map" }}
{{- include "flattenYaml" (dict "prefix" ($prefixedKey) "data" $value) }}
{{- else }}
{{- printf "%s=%s\n" $prefixedKey (toJson $value) }}
{{- end }}
{{- end }}
{{- else }}
{{ toJson . }}#k({{ $knd }})
{{- end }}
{{- end -}}
for more details see my answer there.