TopolearnOptional features and repeated label blocks need conditionals and reusable templates.
Control structures:
{{ if .Values.ingress.enabled }} ... {{ else }} ... {{ end }}: values that are false, 0, empty strings, empty lists/maps and nil are false. Combine withand,or,not,eq.{{ with .Values.nodeSelector }} ... {{ end }}: runs the block only if the value is non-empty, and sets.to it.{{ range .Values.hosts }} ... {{ end }}loops over lists;{{ range $key, $val := .Values.env }}loops over maps in sorted key order.- Variables:
{{ $name := .Release.Name }}. Insidewithandrangethe dot changes, so use$for the root context ($.Release.Name).
Named templates avoid copy-paste. Define them in templates/_helpers.tpl:
{{- define "shop.labels" -}} ... {{- end }}
and use them with {{ include "shop.labels" . | nindent 4 }}. Prefix names with the chart name, because template names are global across a chart and its subcharts. Prefer include over the built-in template action, because include returns a string you can pipe to nindent.
Pass the right context: include "x" . passes the current dot; inside a range you may need include "x" $ or a dict with several values.
Example
{{/* templates/_helpers.tpl */}}
{{- define "shop.labels" -}}
app.kubernetes.io/name: {{ .Chart.Name }}
app.kubernetes.io/instance: {{ .Release.Name }}
app.kubernetes.io/version: {{ .Chart.AppVersion | quote }}
{{- end }}
{{/* templates/configmap.yaml */}}
apiVersion: v1
kind: ConfigMap
metadata:
name: {{ .Release.Name }}-env
labels:
{{- include "shop.labels" . | nindent 4 }}
data:
{{- range $key, $val := .Values.env }}
{{ $key }}: {{ $val | quote }}
{{- end }}
{{- with .Values.extraConfig }}
extra.conf: {{ . | quote }}
{{- end }}Remember
- if/with/range with Go truthiness; $ is the root inside with/range
- define in _helpers.tpl, use with include ... | nindent
- Prefix template names with the chart name
Watch out for
- Using .Release.Name inside a range block, where the dot is the current item; use $.Release.Name.