Helm Templating Cheat Sheet

Helm is a powerful package manager for Kubernetes, and templating is at its core. This cheat sheet provides a quick reference for Helm templating, helping you master Go templates, conditional logic, loops, and helper functions.

📌 Basic Helm Template Syntax

Helm templates use Go templating with sprig functions to dynamically generate Kubernetes manifests.

Basic Syntax

{{ .Values.key }} # Access values from values.yaml
{{ .Release.Name }} # Get the release name
{{ .Chart.Name }} # Get the chart name
{{ .Release.Namespace }} # Get the namespace

Conditions & Loops

{{ if .Values.enabled }}
# YAML if enabled
{{ end }}


{{ range .Values.list }}
- {{ . }}
{{ end }}


{{ with .Values.config }}
# Use . inside this scope
{{ end }}

📌 Default & Ternary Operators

{{ .Values.image | default "nginx:latest" }} # Default value
{{ .Values.env | default "production" }} # Default env

Ternary alternative:

{{ if .Values.debug }} debug: true {{ else }} debug: false {{ end }}

📌 String Manipulation

{{ .Values.name | upper }} # Uppercase
{{ .Values.name | lower }} # Lowercase
{{ .Values.name | quote }} # Wrap in quotes
{{ printf "%s-%s" .Values.variable1 .Values.variable2 }} # concat or custom test formatting

📌 List & Map Functions

{{ .Values.list | join "," }} # Join list items
{{ .Values.dict | keys }} # Get dict keys

📌 File & Secret Encoding

{{ .Files.Get "config.yaml" }} # Load file content
{{ .Files.Get "config.yaml" | b64enc }} # Encode in base64

📌 Template Functions

Define & Include

{{ define "myTemplate" }}
Hello {{ .Values.name }}
{{ end }}

{{ include "myTemplate" . }}

Template Helpers (_helpers.tpl)

{{- define "app.fullname" -}}
{{ .Release.Name }}-{{ .Chart.Name }}
{{- end -}}

name: {{ include "app.fullname" . }}

📌 Conditionally Creating Resources

{{ if .Values.ingress.enabled }}
apiVersion: networking.k8s.io/v1
kind: Ingress
{{ end }}

📌 Loops Example

Looping over a list:

{{ range .Values.hosts }}
- host: {{ . }}
{{ end }}

Looping over a dictionary:

{{ range $key, $value := .Values.configs }}
{{ $key }}: {{ $value }}
{{ end }}

📌 Custom Variables in Templates

Define & Use Custom Variables in Templates

{{- $appName := "my-app" }}  # Define a variable
metadata:
  name: {{ $appName }}  # Use the variable

📌 Example values.yaml

name: my-app
enabled: true
list:
  - item1
  - item2
image: "my-image:latest"
configs:
key1: value1
key2: value2

Conclusion

Mastering Helm templating is essential for deploying scalable and configurable Kubernetes applications. This cheat sheet provides a quick reference for common Helm templating patterns and functions. Happy Helm charting! 🚀

Do you have any favorite Helm tricks? Share them in the comments below! 🔥