Mastering Kubernetes - Second Edition

Using pipelines and functions

Helm allows rich and sophisticated syntax in the template files through the built-in Go template functions, sprig functions, and pipelines. Here is an example template that takes advantage of these capabilities. It uses the repeat, quote, and upper functions for the food and drink keys, and it uses pipelines to chain multiple functions together:

apiVersion: v1 
kind: ConfigMap 
metadata: 
  name: {{ .Release.Name }}-configmap 
data: 
  greeting: "Hello World" 
  drink: {{ .Values.favorite.drink | repeat 3 | quote }} 
  food: {{ .Values.favorite.food | upper | quote }}   

See if the values file has the following section:

favorite: 
  drink: coffee 
  food: pizza 

If it does, then the resulting chart would be as follows:

apiVersion: ...