Helm: The Kubernetes Package Manager

Deploying an application on K8s means writing 5–10 YAML files: Deployment, Service, Ingress, ConfigMap, Secret, HPA… and slightly different files for each environment (dev/staging/prod). Helm solves this problem.

What Is Helm and a Chart

Helm is a package manager for Kubernetes — like apt for Ubuntu or pip for Python.

Chart is a Helm package. It contains a set of YAML templates with variables and a values.yaml file with default values. A single helm install deploys the entire application.

Release is an installed instance of a Chart. You can install one Chart multiple times under different names and with different values.

Chart (template)  →  helm install  →  Release (running application)

Installing Helm

# macOS
brew install helm

# Verify
helm version
# version.BuildInfo{Version:"v3.14.0", ...}

helm install, upgrade, rollback, uninstall

Finding and Installing a Chart

# Add a repository
helm repo add bitnami https://charts.bitnami.com/bitnami
helm repo update

# Search for a chart
helm search repo postgresql
# NAME                    CHART VERSION  APP VERSION  DESCRIPTION
# bitnami/postgresql      13.2.0         16.1.0       PostgreSQL chart

# Inspect chart values
helm show values bitnami/postgresql | head -50

# Install
helm install my-postgres bitnami/postgresql \
  --namespace database \
  --create-namespace \
  --set auth.postgresPassword=mysecretpassword \
  --set primary.persistence.size=10Gi

# List installed releases
helm list -A
# NAME          NAMESPACE  REVISION  STATUS    CHART
# my-postgres   database   1         deployed  postgresql-13.2.0

Upgrading

# Update values without changing the chart version
helm upgrade my-postgres bitnami/postgresql \
  --namespace database \
  --set auth.postgresPassword=newsecretpassword

# Upgrade to a new chart version
helm upgrade my-postgres bitnami/postgresql \
  --namespace database \
  --version 13.3.0

# Upgrade with automatic rollback on failure
helm upgrade --install my-postgres bitnami/postgresql \
  --atomic \
  --timeout 5m

Rollback and Uninstall

# Release history
helm history my-postgres -n database
# REVISION  STATUS     CHART               DESCRIPTION
# 1         superseded  postgresql-13.2.0   Install complete
# 2         deployed    postgresql-13.2.0   Upgrade complete

# Roll back to the previous revision
helm rollback my-postgres -n database

# Roll back to a specific revision
helm rollback my-postgres 1 -n database

# Uninstall (PVC data is preserved)
helm uninstall my-postgres -n database

values.yaml for Parameterisation

The main power of Helm is parameterisation via values.yaml. One Chart, different configs for different environments.

# values.yaml (default values)
replicaCount: 1
image:
  repository: my-app
  tag: "1.0.0"
  pullPolicy: IfNotPresent

service:
  type: ClusterIP
  port: 80

ingress:
  enabled: false
  host: ""

resources:
  requests:
    cpu: 100m
    memory: 128Mi
  limits:
    cpu: 500m
    memory: 256Mi

env:
  LOG_LEVEL: info
  DATABASE_HOST: postgres-service

# values-prod.yaml (overrides for production)
replicaCount: 3
image:
  tag: "1.5.2"

ingress:
  enabled: true
  host: api.example.com

resources:
  requests:
    cpu: 500m
    memory: 512Mi
  limits:
    cpu: 2000m
    memory: 1Gi

env:
  LOG_LEVEL: warning

# Install with a prod values file
helm install my-app ./my-chart \
  -f values.yaml \
  -f values-prod.yaml

# Or use --set for individual overrides
helm install my-app ./my-chart \
  -f values.yaml \
  --set image.tag=1.5.3

Popular Charts

# nginx Ingress Controller
helm repo add ingress-nginx https://kubernetes.github.io/ingress-nginx
helm install ingress-nginx ingress-nginx/ingress-nginx \
  --namespace ingress-nginx --create-namespace

# cert-manager (TLS certificates)
helm repo add jetstack https://charts.jetstack.io
helm install cert-manager jetstack/cert-manager \
  --namespace cert-manager --create-namespace \
  --set installCRDs=true

# Prometheus + Grafana (monitoring)
helm repo add prometheus-community https://prometheus-community.github.io/helm-charts
helm install kube-prometheus prometheus-community/kube-prometheus-stack \
  --namespace monitoring --create-namespace

Creating Your Own Chart

# Generate the chart skeleton
helm create my-app

my-app/
├── Chart.yaml          # chart metadata
├── values.yaml         # default values
├── charts/             # dependencies (sub-charts)
└── templates/          # YAML templates
    ├── deployment.yaml
    ├── service.yaml
    ├── ingress.yaml
    ├── _helpers.tpl    # helper templates
    └── NOTES.txt       # message shown after install

# Chart.yaml
apiVersion: v2
name: my-app
description: A Helm chart for my application
type: application
version: 0.1.0       # chart version
appVersion: "1.0.0"  # application version

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

# Preview the rendered templates before installing
helm template my-app ./my-app -f values-prod.yaml

# Lint and dry-run
helm lint ./my-app
helm install my-app ./my-app --dry-run

# Real install
helm install my-app ./my-app -f values-prod.yaml