Helm Templating in Configmap for values.yaml - templates

Question

I"m looking for help to create a generic configmap.yaml that can support several services.
values.yaml (THIS WORKS)
value1: val1
genericConfigMapProperties:
application.properties: |-
prop1=prop1value
prop2=prop2value
configmap.yaml
apiVersion: 1
kind: ConfigMap
...
...
data:
{{ (toYaml .Values.genericConfigMapProperties) . | ident 4 }}
The template {{ (toYaml .Values.genericConfigMapProperties) . | ident 4 }} is almost perfect. It renders application.properties correctly:
data:
application.properties: |-
prop1=prop1value
prop2=prop2value
values.yaml (THIS DOES NOT WORK)
value1: val1
genericConfigMapProperties:
cmValue1: {{ .Values.value1 | default "default val1" | quote }}
application.properties: |-
prop1=prop1value
prop2=prop2value
It is getting errors rendering cmValue1. I am expecting this answer:
data:
cmValue1: val1
application.properties: |-
prop1=prop1value
prop2=prop2value
Errors:
Error: failed to parse values.yaml: error converting YAML to JSON: yaml: invalid map key: map[interface {}]interface {}{".Values.value1 | default \"default val1\" | quote":interface {}(nill)}
helm.go:88: [debug] error converting YAML to JSON: yaml: invalid map key: map[interface {}]interface {}{".Values.value1 | default \"default val1\" | quote":interface {}(nill)}
failed to parse values.yaml
What additional helm template code do I need to support cmValue1 rendering?
Thank you.

Answer 1

Thank you for responding.
I've found this awesome solution from bitnami common templates. It works just about anywhere.
https://github.com/bitnami/charts/blob/master/bitnami/common/templates/_tplvalues.tpl
Copy this template file:
{{/* vim: set filetype=mustache: */}}
{{/*
Renders a value that contains template.
Usage:
{{ include "common.tplvalues.render" ( dict "value" .Values.path.to.the.Value "context" $) }}
*/}}
{{- define "common.tplvalues.render" -}}
{{- if typeIs "string" .value }}
{{- tpl .value .context }}
{{- else }}
{{- tpl (.value | toYaml) .context }}
{{- end }}
{{- end -}}
Use it to template any values in configmap.yaml or deployment.yaml or anywhere else...
values.yaml:
configMapProperties:
cmValue1: "val1"
application.properties: |-
prop1=prop1value
prop2=prop2value
configmap.yaml
data:
{{- if .Values.configMapProperties }}
{{- include "common.tplvalues.render" ( dict "value" .Values.configMapProperties "context" $ ) | nindent 2 }}
{{- end }}

Answer 2

Helm does not support secondary rendering, but you can use yaml anchor to achieve this function, or indirectly by using named templates.
Plan A : anchor
values.yaml
value1: &value1 val1
genericConfigMapProperties:
cmValue1: *value1
application.properties: |-
prop1=prop1value
prop2=prop2value
templates/configmap.yaml
apiVersion: v1
kind: ConfigMap
metadata:
name: test
data:
config.yaml: |
{{- toYaml $.Values.genericConfigMapProperties | nindent 4 }}
output
apiVersion: v1
kind: ConfigMap
metadata:
name: test
data:
config.yaml: |
application.properties: |-
prop1=prop1value
prop2=prop2value
cmValue1: val1
Plan B: Named Template
values.yaml
value1: val1
templates/_helpers.tpl
{{/*
cmValue template
*/}}
{{- define "genericConfigMapProperties" -}}
cmValue1: {{ .Values.value1 | default "default val1" | quote }}
application.properties: |-
prop1=prop1value
prop2=prop2value
{{- end -}}
templates/configmap.yaml
apiVersion: v1
kind: ConfigMap
metadata:
name: test
data:
config.yaml: |
{{- include "genericConfigMapProperties" . | nindent 4 }}
output
apiVersion: v1
kind: ConfigMap
metadata:
name: test
data:
config.yaml: |
cmValue1: "val1"
application.properties: |-
prop1=prop1value
prop2=prop2value