Helm template basics

Helm templates are used to dynamically generate Kubernetes YAML Ain’t Markup Language (YAML) (or JavaScript Object Notation (JSON)) resources. They consume a set of default and user-provided values to generate resources that comprise a Kubernetes application. You’ve had some exposure to templates already in Chapter 4, Scaffolding a New Helm Chart, when you ran the helm create command, which generated a set of starter templates. In the Git repository cloned previously, these templates are located at chapter6/guestbook/templates/. Here’s a short snippet of the deployment.yaml Helm template, located within the chapter6/guestbook/templates/deployment.yaml file:

apiVersion: apps/v1
kind: Deployment
metadata:
  name: {{ include "guestbook.fullname" . }}
  labels:
    {{- include "guestbook.labels" . | nindent 4 }}
spec:
  {{- if not .Values.autoscaling.enabled }}
  ...