Helm Charts

Helm Charts Skill

Overview

Helm is the package manager for Kubernetes. It packages Kubernetes manifests into reusable charts that can be versioned, shared, and deployed with customizable values.

Core Concepts

What is a Helm Chart?

A chart is a collection of files that describe a related set of Kubernetes resources:

mychart/
├── Chart.yaml          # Chart metadata (name, version, dependencies)
├── values.yaml         # Default configuration values
├── charts/             # Dependency charts
├── templates/          # Kubernetes manifest templates
│   ├── deployment.yaml
│   ├── service.yaml
│   ├── ingress.yaml
│   ├── configmap.yaml
│   ├── secret.yaml
│   ├── _helpers.tpl    # Template helpers
│   └── NOTES.txt       # Post-install notes
└── .helmignore         # Files to ignore when packaging

Key Files

Chart.yaml Structure

apiVersion: v2                    # Helm 3 uses v2
name: taskflow                    # Chart name
description: TaskFlow Platform    # Short description
type: application                 # application or library
version: 1.0.0                    # Chart version (SemVer)
appVersion: "1.0.0"               # Application version

# Dependencies (optional)
dependencies:
  - name: postgresql
    version: "12.x.x"
    repository: "https://charts.bitnami.com/bitnami"
    condition: postgresql.enabled

values.yaml Pattern

# Global settings
global:
  imageRegistry: ""
  imagePullSecrets: []

# Per-service configuration
api:
  replicaCount: 1
  image:
    repository: taskflow/api
    tag: "latest"
    pullPolicy: IfNotPresent
  service:
    type: ClusterIP
    port: 8000
  resources:
    limits:
      cpu: 500m
      memory: 512Mi
    requests:
      cpu: 100m
      memory: 128Mi
  env:
    DATABASE_URL: ""
    SSO_URL: "http://sso:3001"

# Feature flags
postgresql:
  enabled: true
  auth:
    postgresPassword: "postgres"
    database: "taskflow"

Template Syntax

Accessing Values

# templates/deployment.yaml
apiVersion: apps/v1
kind: Deployment
metadata:
  name: {{ include "taskflow.fullname" . }}
  labels:
    {{- include "taskflow.labels" . | nindent 4 }}
spec:
  replicas: {{ .Values.api.replicaCount }}
  selector:
    matchLabels:
      {{- include "taskflow.selectorLabels" . | nindent 6 }}
  template:
    spec:
      containers:
        - name: {{ .Chart.Name }}
          image: "{{ .Values.api.image.repository }}:{{ .Values.api.image.tag }}"
          ports:
            - containerPort: {{ .Values.api.service.port }}
          env:
            - name: DATABASE_URL
              value: {{ .Values.api.env.DATABASE_URL | quote }}

Helper Templates (_helpers.tpl)

{{/*
Expand the name of the chart.
*/}}
{{- define "taskflow.name" -}}
{{- default .Chart.Name .Values.nameOverride | trunc 63 | trimSuffix "-" }}
{{- end }}

{{/*
Create a default fully qualified app name.
*/}}
{{- define "taskflow.fullname" -}}
{{- if .Values.fullnameOverride }}
{{- .Values.fullnameOverride | trunc 63 | trimSuffix "-" }}
{{- else }}
{{- $name := default .Chart.Name .Values.nameOverride }}
{{- printf "%s-%s" .Release.Name $name | trunc 63 | trimSuffix "-" }}
{{- end }}
{{- end }}

{{/*
Common labels
*/}}
{{- define "taskflow.labels" -}}
helm.sh/chart: {{ include "taskflow.chart" . }}
{{ include "taskflow.selectorLabels" . }}
app.kubernetes.io/managed-by: {{ .Release.Service }}
{{- end }}

{{/*
Selector labels
*/}}
{{- define "taskflow.selectorLabels" -}}
app.kubernetes.io/name: {{ include "taskflow.name" . }}
app.kubernetes.io/instance: {{ .Release.Name }}
{{- end }}

Essential Commands

Create New Chart

helm create mychart

Install Chart

# From local directory
helm install my-release ./mychart

# With custom values file
helm install my-release ./mychart --values custom-values.yaml

# With inline value overrides
helm install my-release ./mychart \
  --set api.replicaCount=3 \
  --set api.image.tag=v2.0.0

# To specific namespace (create if needed)
helm install my-release ./mychart \
  --namespace production \
  --create-namespace

# Dry run (preview without installing)
helm install my-release ./mychart --dry-run --debug

Upgrade Release

helm upgrade my-release ./mychart --values new-values.yaml

Rollback

helm rollback my-release 1  # Rollback to revision 1

Uninstall

helm uninstall my-release

List Releases

helm list
helm list --all-namespaces

Debug Templates

# Render templates without installing
helm template my-release ./mychart

# Debug with computed values
helm template my-release ./mychart --debug

Multi-Service Chart Pattern

For TaskFlow (api, sso, web, mcp-server), use a single chart with multiple templates:

helm/taskflow/
├── Chart.yaml
├── values.yaml
├── templates/
│   ├── _helpers.tpl
│   ├── NOTES.txt
│   ├── api/
│   │   ├── deployment.yaml
│   │   ├── service.yaml
│   │   └── configmap.yaml
│   ├── sso/
│   │   ├── deployment.yaml
│   │   └── service.yaml
│   ├── web/
│   │   ├── deployment.yaml
│   │   └── service.yaml
│   ├── mcp-server/
│   │   ├── deployment.yaml
│   │   └── service.yaml
│   └── ingress.yaml

ConfigMap and Secrets

ConfigMap Template

apiVersion: v1
kind: ConfigMap
metadata:
  name: {{ include "taskflow.fullname" . }}-config
data:
  SSO_URL: {{ .Values.sso.url | quote }}
  API_URL: {{ .Values.api.url | quote }}

Secret Template (from values)

apiVersion: v1
kind: Secret
metadata:
  name: {{ include "taskflow.fullname" . }}-secrets
type: Opaque
data:
  database-url: {{ .Values.secrets.databaseUrl | b64enc | quote }}
  openai-api-key: {{ .Values.secrets.openaiApiKey | b64enc | quote }}

Health Checks Pattern

spec:
  containers:
    - name: api
      livenessProbe:
        httpGet:
          path: /health
          port: 8000
        initialDelaySeconds: 30
        periodSeconds: 10
      readinessProbe:
        httpGet:
          path: /health
          port: 8000
        initialDelaySeconds: 5
        periodSeconds: 5

Ingress Pattern

{{- if .Values.ingress.enabled -}}
apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
  name: {{ include "taskflow.fullname" . }}
  annotations:
    {{- toYaml .Values.ingress.annotations | nindent 4 }}
spec:
  ingressClassName: {{ .Values.ingress.className }}
  rules:
    - host: {{ .Values.ingress.host }}
      http:
        paths:
          - path: /api
            pathType: Prefix
            backend:
              service:
                name: {{ include "taskflow.fullname" . }}-api
                port:
                  number: 8000
          - path: /
            pathType: Prefix
            backend:
              service:
                name: {{ include "taskflow.fullname" . }}-web
                port:
                  number: 3000
{{- end }}

Common Gotchas

1. Quote strings in templates: Use {{ .Values.foo | quote }} for strings
2. Indentation matters: Use nindent for proper YAML formatting
3. Resource names: Keep under 63 characters (K8s limit)
4. Image pull policy: Use IfNotPresent in production, Always in dev
5. Secrets: Never commit real secrets to values.yaml

Resources

Refer to references/ for:

• chart-patterns.md - Advanced templating patterns
• values-structure.md - Values.yaml organization guide

Refer to assets/ for:

• base-chart/ - Complete starter chart template