helm

Helm

Helm is the package manager for Kubernetes, enabling declarative application packaging, versioned chart releases, OCI registry distribution, and automated rollbacks.

When to Use

• Kubernetes Package Management: Packaging, templating, versioning, and deploying complex Kubernetes applications.
• Multi-Environment Value Overrides: Reusing a single chart across dev, staging, and production with distinct values.yaml files.
• Third-Party Open-Source Deployment: Installing community software (Cert-Manager, Ingress-Nginx, Prometheus) via Helm Repos.
• Release Lifecycle & Rollbacks: Upgrading, tracking release revisions, and executing automated rollbacks via helm rollback.

Quick Start

# Install a chart
helm install my-release oci://registry-1.docker.io/bitnamicharts/nginx

# Create a chart
helm create my-chart

# values.yaml
replicaCount: 2
image:
  repository: nginx
  tag: "1.25"

Core Concepts

Parameterized Deployment Template

Templating Kubernetes resources with Helm helpers:

# templates/deployment.yaml
apiVersion: apps/v1
kind: Deployment
metadata:
  name: {{ include "mychart.fullname" . }}
  labels:
    {{- include "mychart.labels" . | nindent 4 }}
spec:
  replicas: {{ .Values.replicaCount }}
  selector:
    matchLabels:
      {{- include "mychart.selectorLabels" . | nindent 6 }}
  template:
    metadata:
      labels:
        {{- include "mychart.selectorLabels" . | nindent 8 }}
    spec:
      containers:
        - name: {{ .Chart.Name }}
          image: "{{ .Values.image.repository }}:{{ .Values.image.tag | default .Chart.AppVersion }}"
          imagePullPolicy: {{ .Values.image.pullPolicy }}
          ports:
            - containerPort: {{ .Values.service.port }}
          resources:
            {{- toYaml .Values.resources | nindent 12 }}

Values Schema Validation (values.schema.json)

Enforcing strict type checking on user-provided values:

{
  "$schema": "https://json-schema.org/draft-07/schema#",
  "properties": {
    "replicaCount": {
      "type": "integer",
      "minimum": 1
    },
    "image": {
      "type": "object",
      "required": ["repository"],
      "properties": {
        "repository": { "type": "string" },
        "tag": { "type": "string" }
      }
    }
  },
  "required": ["replicaCount", "image"]
}