# Helm Chart Development > Use when creating new Helm charts from scratch, designing values.yaml schema and structure, implementing Helm template patterns, setting up chart directory structure, writing template helpers (_helpers.tpl), or creating values.schema.json validation - Skill: `tomevault-io/helm-chart-development` (Agent Skill, multi-file: 2 files) - Install (CLI): `npx skillmds@latest add tomevault-io/helm-chart-development` - Raw SKILL.md: https://api.skillmd.com/api/skills/tomevault-io/helm-chart-development/raw - Safety review: pending - Works with: Claude Code, Claude.ai, OpenAI Codex - Category: DevOps & Infra - Author: tomevault-io (https://skillmd.com/u/tomevault-io) - Updated: 2026-09-17 - Page: https://skillmd.com/skills/tomevault-io/helm-chart-development --- # Helm Chart Development Create and structure Helm charts following best practices, including templating, values design, and chart architecture. ## Keywords helm, chart, development, templating, template, values, schema, kubernetes, packaging, creating, create, scaffold, scaffolding, helpers, deployment, deploying, writing, designing, structure ## When to Use This Skill - Creating new Helm charts from scratch - Designing values.yaml schema and structure - Implementing Helm template patterns - Setting up chart directory structure - Writing template helpers (_helpers.tpl) - Creating values.schema.json validation ## Related Skills - [helm-chart-maintenance](../helm-chart-maintenance) - Versioning and updates - [helm-chart-review](../helm-chart-review) - Quality and security review - [k8s-security-hardening](../k8s-security-hardening) - Security best practices - [Shared: Pod Security Context](../_shared/references/pod-security-context.md) ## Quick Reference | Task | Command | |------|---------| | Create chart | `helm create mychart` | | Lint chart | `helm lint mychart/` | | Template dry-run | `helm template myrelease mychart/ -f values.yaml` | | Package chart | `helm package mychart/` | | Install debug | `helm install myrelease mychart/ --debug --dry-run` | ## Chart Structure ### Standard Layout ``` mychart/ ├── Chart.yaml ├── Chart.lock ├── values.yaml ├── values.schema.json ├── README.md ├── LICENSE ├── .helmignore ├── templates/ │ ├── NOTES.txt │ ├── _helpers.tpl │ ├── deployment.yaml │ ├── service.yaml │ ├── ingress.yaml │ ├── configmap.yaml │ ├── secret.yaml │ ├── serviceaccount.yaml │ ├── hpa.yaml │ └── tests/ │ └── test-connection.yaml ├── charts/ └── crds/ ``` ## Chart.yaml ### Complete Example ```yaml apiVersion: v2 name: myapp description: A Helm chart for MyApp type: application version: 1.0.0 appVersion: "2.3.1" home: https://github.com/org/myapp icon: https://example.com/icon.png sources: - https://github.com/org/myapp maintainers: - name: Platform Team email: platform@company.com url: https://platform.company.com keywords: - app - web annotations: artifacthub.io/changes: | - kind: added description: Initial release artifacthub.io/license: Apache-2.0 dependencies: - name: postgresql version: "12.x.x" repository: https://charts.bitnami.com/bitnami condition: postgresql.enabled tags: - database - name: redis version: "17.x.x" repository: https://charts.bitnami.com/bitnami condition: redis.enabled import-values: - child: primary parent: redis ``` ## Values Design ### Well-Structured values.yaml ```yaml # -- Number of replicas replicaCount: 1 image: # -- Image repository repository: myapp # -- Image pull policy pullPolicy: IfNotPresent # -- Image tag (defaults to appVersion) tag: "" # -- Image pull secrets imagePullSecrets: [] # -- Override chart name nameOverride: "" # -- Override full name fullnameOverride: "" serviceAccount: # -- Create service account create: true # -- Service account annotations annotations: {} # -- Service account name (generated if not set) name: "" # -- Automount service account token automount: true # -- Pod annotations podAnnotations: {} # -- Pod labels podLabels: {} podSecurityContext: fsGroup: 1000 runAsNonRoot: true securityContext: allowPrivilegeEscalation: false readOnlyRootFilesystem: true runAsNonRoot: true runAsUser: 1000 capabilities: drop: - ALL service: # -- Service type type: ClusterIP # -- Service port port: 80 # -- Target port targetPort: 8080 # -- Node port (when type is NodePort) nodePort: "" ingress: # -- Enable ingress enabled: false # -- Ingress class name className: "" # -- Ingress annotations annotations: {} # -- Ingress hosts hosts: - host: chart-example.local paths: - path: / pathType: Prefix # -- Ingress TLS configuration tls: [] resources: limits: cpu: 500m memory: 512Mi requests: cpu: 100m memory: 128Mi autoscaling: enabled: false minReplicas: 1 maxReplicas: 10 targetCPUUtilizationPercentage: 80 targetMemoryUtilizationPercentage: 80 # -- Node selector nodeSelector: {} # -- Tolerations tolerations: [] # -- Affinity rules affinity: {} # -- Extra environment variables extraEnv: [] # -- Extra volume mounts extraVolumeMounts: [] # -- Extra volumes extraVolumes: [] # -- Liveness probe configuration livenessProbe: httpGet: path: /healthz port: http initialDelaySeconds: 10 periodSeconds: 10 # -- Readiness probe configuration readinessProbe: httpGet: path: /ready port: http initialDelaySeconds: 5 periodSeconds: 5 # Subchart configuration postgresql: enabled: false auth: database: myapp username: myapp ``` ## Template Helpers (_helpers.tpl) ```yaml {{/* Expand the name of the chart. */}} {{- define "myapp.name" -}} {{- default .Chart.Name .Values.nameOverride | trunc 63 | trimSuffix "-" }} {{- end }} {{/* Create a default fully qualified app name. */}} {{- define "myapp.fullname" -}} {{- if .Values.fullnameOverride }} {{- .Values.fullnameOverride | trunc 63 | trimSuffix "-" }} {{- else }} {{- $name := default .Chart.Name .Values.nameOverride }} {{- if contains $name .Release.Name }} {{- .Release.Name | trunc 63 | trimSuffix "-" }} {{- else }} {{- printf "%s-%s" .Release.Name $name | trunc 63 | trimSuffix "-" }} {{- end }} {{- end }} {{- end }} {{/* Create chart name and version for chart label. */}} {{- define "myapp.chart" -}} {{- printf "%s-%s" .Chart.Name .Chart.Version | replace "+" "_" | trunc 63 | trimSuffix "-" }} {{- end }} {{/* Common labels */}} {{- define "myapp.labels" -}} helm.sh/chart: {{ include "myapp.chart" . }} {{ include "myapp.selectorLabels" . }} {{- if .Chart.AppVersion }} app.kubernetes.io/version: {{ .Chart.AppVersion | quote }} {{- end }} app.kubernetes.io/managed-by: {{ .Release.Service }} {{- end }} {{/* Selector labels */}} {{- define "myapp.selectorLabels" -}} app.kubernetes.io/name: {{ include "myapp.name" . }} app.kubernetes.io/instance: {{ .Release.Name }} {{- end }} {{/* Create the name of the service account to use */}} {{- define "myapp.serviceAccountName" -}} {{- if .Values.serviceAccount.create }} {{- default (include "myapp.fullname" .) .Values.serviceAccount.name }} {{- else }} {{- default "default" .Values.serviceAccount.name }} {{- end }} {{- end }} {{/* Return the proper image name */}} {{- define "myapp.image" -}} {{- $tag := .Values.image.tag | default .Chart.AppVersion -}} {{- printf "%s:%s" .Values.image.repository $tag }} {{- end }} ``` ## Template Patterns ### Deployment Template ```yaml apiVersion: apps/v1 kind: Deployment metadata: name: {{ include "myapp.fullname" . }} labels: {{- include "myapp.labels" . | nindent 4 }} spec: {{- if not .Values.autoscaling.enabled }} replicas: {{ .Values.replicaCount }} {{- end }} selector: matchLabels: {{- include "myapp.selectorLabels" . | nindent 6 }} template: metadata: annotations: checksum/config: {{ include (print $.Template.BasePath "/configmap.yaml") . | sha256sum }} {{- with .Values.podAnnotations }} {{- toYaml . | nindent 8 }} {{- end }} labels: {{- include "myapp.labels" . | nindent 8 }} {{- with .Values.podLabels }} {{- toYaml . | nindent 8 }} {{- end }} spec: {{- with .Values.imagePullSecrets }} imagePullSecrets: {{- toYaml . | nindent 8 }} {{- end }} serviceAccountName: {{ include "myapp.serviceAccountName" . }} securityContext: {{- toYaml .Values.podSecurityContext | nindent 8 }} containers: - name: {{ .Chart.Name }} securityContext: {{- toYaml .Values.securityContext | nindent 12 }} image: {{ include "myapp.image" . }} imagePullPolicy: {{ .Values.image.pullPolicy }} ports: - name: http containerPort: {{ .Values.service.targetPort }} protocol: TCP {{- with .Values.livenessProbe }} livenessProbe: {{- toYaml . | nindent 12 }} {{- end }} {{- with .Values.readinessProbe }} readinessProbe: {{- toYaml . | nindent 12 }} {{- end }} resources: {{- toYaml .Values.resources | nindent 12 }} {{- with .Values.extraEnv }} env: {{- toYaml . | nindent 12 }} {{- end }} {{- with .Values.extraVolumeMounts }} volumeMounts: {{- toYaml . | nindent 12 }} {{- end }} {{- with .Values.extraVolumes }} volumes: {{- toYaml . | nindent 8 }} {{- end }} {{- with .Values.nodeSelector }} nodeSelector: {{- toYaml . | nindent 8 }} {{- end }} {{- with .Values.affinity }} affinity: {{- toYaml . | nindent 8 }} {{- end }} {{- with .Values.tolerations }} tolerations: {{- toYaml . | nindent 8 }} {{- end }} ``` ### Conditional Resource ```yaml {{- if .Values.ingress.enabled -}} apiVersion: networking.k8s.io/v1 kind: Ingress metadata: name: {{ include "myapp.fullname" . }} labels: {{- include "myapp.labels" . | nindent 4 }} {{- with .Values.ingress.annotations }} annotations: {{- toYaml . | nindent 4 }} {{- end }} spec: {{- if .Values.ingress.className }} ingressClassName: {{ .Values.ingress.className }} {{- end }} {{- if .Values.ingress.tls }} tls: {{- range .Values.ingress.tls }} - hosts: {{- range .hosts }} - {{ . | quote }} {{- end }} secretName: {{ .secretName }} {{- end }} {{- end }} rules: {{- range .Values.ingress.hosts }} - host: {{ .host | quote }} http: paths: {{- range .paths }} - path: {{ .path }} pathType: {{ .pathType }} backend: service: name: {{ include "myapp.fullname" $ }} port: number: {{ $.Values.service.port }} {{- end }} {{- end }} {{- end }} ``` ## Values Schema (values.schema.json) ```json { "$schema": "https://json-schema.org/draft/2020-12/schema", "type": "object", "required": ["image"], "properties": { "replicaCount": { "type": "integer", "minimum": 1, "description": "Number of replicas" }, "image": { "type": "object", "required": ["repository"], "properties": { "repository": { "type": "string", "description": "Image repository" }, "tag": { "type": "string", "description": "Image tag" }, "pullPolicy": { "type": "string", "enum": ["Always", "IfNotPresent", "Never"], "default": "IfNotPresent" } } }, "resources": { "type": "object", "properties": { "limits": { "type": "object", "properties": { "cpu": { "type": "string" }, "memory": { "type": "string" } } }, "requests": { "type": "object", "properties": { "cpu": { "type": "string" }, "memory": { "type": "string" } } } } } } } ``` ## NOTES.txt Template ```yaml {{- $fullName := include "myapp.fullname" . -}} 1. Get the application URL by running these commands: {{- if .Values.ingress.enabled }} {{- range $host := .Values.ingress.hosts }} {{- range .paths }} http{{ if $.Values.ingress.tls }}s{{ end }}://{{ $host.host }}{{ .path }} {{- end }} {{- end }} {{- else if contains "NodePort" .Values.service.type }} export NODE_PORT=$(kubectl get --namespace {{ .Release.Namespace }} -o jsonpath="{.spec.ports[0].nodePort}" services {{ $fullName }}) export NODE_IP=$(kubectl get nodes --namespace {{ .Release.Namespace }} -o jsonpath="{.items[0].status.addresses[0].address}") echo http://$NODE_IP:$NODE_PORT {{- else if contains "LoadBalancer" .Values.service.type }} NOTE: It may take a few minutes for the LoadBalancer IP to be available. Watch status: kubectl get --namespace {{ .Release.Namespace }} svc -w {{ $fullName }} export SERVICE_IP=$(kubectl get svc --namespace {{ .Release.Namespace }} {{ $fullName }} --template "{{"{{ range (index .status.loadBalancer.ingress 0) }}{{.}}{{ end }}"}}") echo http://$SERVICE_IP:{{ .Values.service.port }} {{- else if contains "ClusterIP" .Values.service.type }} kubectl --namespace {{ .Release.Namespace }} port-forward svc/{{ $fullName }} 8080:{{ .Values.service.port }} echo "Visit http://127.0.0.1:8080" {{- end }} ``` ## Templating Tips ### Whitespace Control ```yaml # Use {{- and -}} to trim whitespace {{- if .Values.enabled }} key: value {{- end }} # Use nindent for proper indentation labels: {{- include "myapp.labels" . | nindent 2 }} ``` ### Required Values ```yaml # Fail if value not set image: {{ required "image.repository is required" .Values.image.repository }} ``` ### Default Values ```yaml # Provide default port: {{ .Values.port | default 8080 }} # Coalesce (first non-empty) name: {{ coalesce .Values.name .Values.nameOverride .Chart.Name }} ``` ### Loops and Ranges ```yaml # Range over list {{- range .Values.hosts }} - {{ . | quote }} {{- end }} # Range with index {{- range $index, $host := .Values.hosts }} - name: host-{{ $index }} value: {{ $host }} {{- end }} # Range over map {{- range $key, $value := .Values.env }} - name: {{ $key }} value: {{ $value | quote }} {{- end }} ``` ## CLI Commands ```bash # Create new chart helm create mychart # Lint chart helm lint mychart/ # Template locally (dry-run) helm template myrelease mychart/ -f values.yaml # Package chart helm package mychart/ # Install with debug helm install myrelease mychart/ --debug --dry-run ``` --- > Converted and distributed by [TomeVault](https://tomevault.io/claim/foxj77) — claim your Tome and manage your conversions.