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helm-templates-cheatsheet.md

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50 Helm Template Cheatsheets
7

Basic Template Functions:

  1. Access a Value from values.yaml:

    replicas: {{ .Values.replicaCount }}

  2. Access Release Information:

    releaseName: {{ .Release.Name }}
releaseNamespace: {{ .Release.Namespace }}

  3. Access Chart Information:

    chartName: {{ .Chart.Name }}
chartVersion: {{ .Chart.Version }}

  4. Port Configuration:

    containerPort: {{ .Values.containerPort }}

Conditional Blocks:

  1. Conditional Rendering:

    {{- if .Values.enableFeature }}
featureEnabled: true
{{- end }}

  2. Conditional Rendering with Else Block:

    {{- if .Values.enableFeature }}
featureEnabled: true
{{- else }}
featureEnabled: false
{{- end }}

Loops:

  1. Loop Over a List:

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

  2. Loop Over a Map:

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

Accessing Values:

  1. Access Nested Values:

    username: {{ .Values.database.credentials.username }}

  2. Quoting a Value:

    message: {{ .Values.message | quote }}

Including Partial Templates:

  1. Include a Partial Template: 
    {{- include "partials.common" . | indent 2 }}

Template Functions:

  1. Convert to YAML:

    {{- toYaml .Values.config | nindent 4 }}

  2. Convert to JSON:

    jsonData: {{ toJson .Values.data }}

  3. Using Sprig Functions:

    password: {{ randAlphaNum 10 | quote }}

Helm Hook Templates:

  1. Pre-install Hook:

    {{- if .Values.preInstallJob }}
# pre-install job definition
{{- end }}

  2. Post-install Hook:

    {{- if .Values.postInstallJob }}
# post-install job definition
{{- end }}

Advanced Examples:

  1. Creating a Kubernetes Secret:

    apiVersion: v1
kind: Secret
metadata:
  name: {{ .Release.Name }}-secret
type: Opaque
data:
  password: {{ .Values.secret.password | b64enc }}

  2. Creating a Service:

    apiVersion: v1
kind: Service
metadata:
  name: {{ include "mychart.fullname" . }}

  3. Defining a ConfigMap:

    apiVersion: v1
kind: ConfigMap
metadata:
  name: {{ include "mychart.fullname" . }}
data:
  config.yaml: |
    {{ .Files.Get "config.yaml" | indent 4 }}

  4. Creating an Ingress:

    apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
  name: {{ include "mychart.fullname" . }}
spec:
  rules:
    - host: {{ .Values.ingress.host }}

  5. Defining a PersistentVolumeClaim:

    apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: {{ include "mychart.fullname" . }}-data

  6. Setting Resource Limits:

    resources:
  limits:
    cpu: {{ .Values.resources.cpu | quote }}
    memory: {{ .Values.resources.memory | quote }}

  7. Creating a Job:

    apiVersion: batch/v1
kind: Job
metadata:
  name: {{ .Release.Name }}-job
spec:
  template:
    spec:
      containers:
      - name: {{ .Chart.Name }}-job
        image: "{{ .Values.image.repository }}:{{ .Values.image.tag }}"
        command: ["{{ .Values.command }}"]

  8. Creating a CronJob:

    apiVersion: batch/v1beta1
kind: CronJob
metadata:
  name: {{ .Release.Name }}-cronjob
spec:
  schedule: "*/1 * * * *"
  jobTemplate:
    spec:
      template:
        spec:
          containers:
          - name: {{ .Chart.Name }}-cronjob
            image: "{{ .Values.image.repository }}:{{ .Values.image.tag }}"
            command: ["{{ .Values.command }}"]

  9. Creating a StatefulSet:

    apiVersion: apps/v1
kind: StatefulSet
metadata:
  name: {{ .Release.Name }}-statefulset

  10. Creating a Deployment with Liveness and Readiness Probes:

    apiVersion: apps/v1
kind: Deployment
metadata:
  name: {{ .Release.Name }}-deployment
spec:
  template:
    spec:
      containers:
      - name: {{ .Chart.Name }}-container
        image: "{{ .Values.image.repository }}:{{ .Values.image.tag }}"
        livenessProbe:
          httpGet:
            path: /healthz
            port: 80
          initialDelaySeconds: 30
        readinessProbe:
          httpGet:
            path: /readyz
            port: 80
          initialDelaySeconds: 5

  11. Creating a Horizontal Pod Autoscaler (HPA):

    apiVersion: autoscaling/v2beta2
kind: HorizontalPodAutoscaler
metadata:
  name: {{ .Release.Name }}-hpa
spec:
  scaleTargetRef:
    apiVersion: apps/v1
    kind: Deployment
    name: {{ .Release.Name }}-deployment
  minReplicas: 1
  maxReplicas: 10
  metrics:
  - type: Resource
    resource:
      name: cpu
      targetAverageUtilization: 50

Accessing Values:

  1. Accessing Values from Dependencies:

    dependencyValue: {{ .Values.dependencies.subchart.value }}

  2. Accessing Values with Default:

    port: {{ .Values.port | default 8080 }}

Advanced Conditional Blocks:

  1. Conditional Block with Nested Conditions:

    {{- if and .Values.condition1 .Values.condition2 }}
# Block content
{{- end }}

  2. Conditional Block with OR Operator:

    {{- if or .Values.condition1 .Values.condition2 }}
# Block content
{{- end }}

Advanced Loops:

  1. Loop with Index:

    {{- range $index, $element := .Values.list }}
- index: {{ $index }}, value: {{ $element }}
{{- end }}

  2. Loop with Sorting:

    {{- range sort .Values.list }}
- value: {{ . }}
{{- end }}

Advanced Template Functions:

  1. Using tpl Function for Advanced Template Rendering:

    renderedTemplate: {{ tpl (.Files.Get "template.yaml") . | indent 4 }}

  2. Using include with Dynamic Name:

    {{- include (printf "%s-config" .Values.serviceName) . | indent 2 }}

External Template Files:

  1. Including External Template File: 
    {{- include "external-template.tpl" . | indent 2 }}

Debugging:

  1. Printing Values for Debugging: 
    {{- printf "%#v" .Values | nindent 2 }}

Naming Conventions:

  1. Using Release Name and Chart Name for Naming Resources: 
    metadata:
  name: {{ .Release.Name }}-{{ .Chart.Name }}

Comments:

  1. Adding Comments in Templates: 
    # This is a comment

External Resources:

  1. Mounting External Files as ConfigMaps: 
    apiVersion: v1
kind: ConfigMap
metadata:
  name: my-configmap
data:
  {{ .Files.Get "config-file.yaml" | indent 2 }}

Combining Functions:

  1. Combining Functions for Complex Operations: 
    combinedValue: {{ trimPrefix "prefix-" (upper .Values.value) }}

Advanced StatefulSet Configuration:

  1. StatefulSet with Persistent Volume Claim: 
    volumeClaimTemplates:
  - metadata:
      name: data
    spec:
      accessModes: [ "ReadWriteOnce" ]
      resources:
        requests:
          storage: 1Gi

External Secrets:

  1. Referencing External Secrets: 
    apiVersion: v1
kind: Secret
metadata:
  name: my-secret
  annotations:
    "helm.sh/resource-policy": keep
type: Opaque
data:
  password: {{ .Values.externalSecret.password | b64enc }}

Helm Release Specifics:

  1. Accessing Release Timestamp: 
    releaseDate: {{ .Release.Timestamp }}

Debugging with printf:

  1. Debugging with printf: 
    {{ printf "%#v" .Values | nindent 2 }}

Using quote and unquote Functions:

  1. Quoting and Unquoting Values: 
    quotedValue: {{ .Values.someValue | quote }}
unquotedValue: {{ .Values.quotedValue | unquote }}

Advanced Resource Definitions:

  1. Advanced Pod Annotations: 
    annotations:
  myAnnotation: {{ .Values.annotations.myAnnotation | quote }}

Configurable Labels:

  1. Configurable Labels: 
    labels:
  myLabel: {{ .Values.labels.myLabel | quote }}

Conditional Pod Disruption Budget:

  1. Conditional Pod Disruption Budget: 
    {{- if .Values.enablePodDisruptionBudget }}
apiVersion: policy/v1beta1
kind: PodDisruptionBudget
metadata:
  name: {{ include "mychart.fullname" . }}
spec:
  # PDB specification
{{- end }}

Helm Template Debugging:

  1. Template Debugging with required Function: 
    requiredValue: {{ required "Value is required" .Values.requiredValue }}

Multiple pipelines:

  1. Manipulate value with multiple pipelines: 
    domain: {{ .Values.domain | lower | trunc 9 | quote}}