Lab 06: Helm Charts

Objectives

• ✅ Understand Helm chart structure
• ✅ Create a Helm chart from scratch
• ✅ Template values and iterate through loops
• ✅ Deploy with Helm
• ✅ Upgrade and rollback releases
• ✅ Manage dependencies

Prerequisites

• Lab 05 complete
• Helm CLI installed
• ~2 hours

Step 1: Create Chart from Scratch

# Create new chart
helm create myapp-chart

# Explore structure
cd myapp-chart
tree
# Should show:
# ├── Chart.yaml
# ├── values.yaml
# ├── templates/
# │   ├── deployment.yaml
# │   ├── service.yaml
# │   └── ...

Step 2: Edit Chart Metadata

Edit Chart.yaml:

apiVersion: v2
name: myapp
description: Sample app for learning Helm
type: application
version: 1.0.0
appVersion: "1.0.0"
keywords:
  - microservices
  - kubernetes
  - helm
maintainers:
  - name: DevOps Team
    email: devops@example.com

Step 3: Customize values.yaml

Edit values.yaml:

replicaCount: 3

image:
  repository: YOUR_USERNAME/myapp
  tag: "1.0.0"
  pullPolicy: IfNotPresent

service:
  type: ClusterIP
  port: 80
  targetPort: 5000

ingress:
  enabled: false

resources:
  requests:
    memory: "256Mi"
    cpu: "100m"
  limits:
    memory: "512Mi"
    cpu: "500m"

autoscaling:
  enabled: false
  minReplicas: 3
  maxReplicas: 10
  targetCPUUtilizationPercentage: 70

config:
  logLevel: INFO
  environment: development

Step 4: Template deployment.yaml

Edit templates/deployment.yaml:

apiVersion: apps/v1
kind: Deployment
metadata:
  name: {{ .Release.Name }}-api
  labels:
    app: {{ .Chart.Name }}
    version: {{ .Chart.Version }}
spec:
  replicas: {{ .Values.replicaCount }}
  selector:
    matchLabels:
      app: {{ .Chart.Name }}
  template:
    metadata:
      labels:
        app: {{ .Chart.Name }}
    spec:
      containers:
      - name: api
        image: "{{ .Values.image.repository }}:{{ .Values.image.tag }}"
        imagePullPolicy: {{ .Values.image.pullPolicy }}
        ports:
        - containerPort: {{ .Values.service.targetPort }}
        env:
        - name: LOG_LEVEL
          value: {{ .Values.config.logLevel }}
        - name: ENVIRONMENT
          value: {{ .Values.config.environment }}
        resources:
          requests:
            memory: "{{ .Values.resources.requests.memory }}"
            cpu: "{{ .Values.resources.requests.cpu }}"
          limits:
            memory: "{{ .Values.resources.limits.memory }}"
            cpu: "{{ .Values.resources.limits.cpu }}"
        livenessProbe:
          httpGet:
            path: /health
            port: {{ .Values.service.targetPort }}
          initialDelaySeconds: 10
          periodSeconds: 5
        readinessProbe:
          httpGet:
            path: /ready
            port: {{ .Values.service.targetPort }}
          initialDelaySeconds: 5
          periodSeconds: 10

Step 5: Template service.yaml

Edit templates/service.yaml:

apiVersion: v1
kind: Service
metadata:
  name: {{ .Release.Name }}-api
spec:
  type: {{ .Values.service.type }}
  selector:
    app: {{ .Chart.Name }}
  ports:
  - protocol: TCP
    port: {{ .Values.service.port }}
    targetPort: {{ .Values.service.targetPort }}

Step 6: Template YAML Preview

# See generated manifests before deploying
helm template myapp-release ./myapp-chart

# Validate syntax
helm lint ./myapp-chart
# Should show: 1 chart(s) linted, 0 error(s)

Step 7: Install Release

# Install with default values
helm install my-app ./myapp-chart

# Or with overrides
helm install my-app ./myapp-chart \
  --set replicaCount=5 \
  --set image.tag=2.0.0

# List releases
helm list

# Get release values
helm get values my-app

# Get generated manifests
helm get manifest my-app

Step 8: Upgrade Release

# Update image version
helm upgrade my-app ./myapp-chart --set image.tag=2.0.0

# Check status
helm status my-app

# View release history
helm history my-app

Step 9: Rollback Release

# Rollback to previous version
helm rollback my-app

# Or to specific revision
helm rollback my-app 1

# Verify
helm status my-app

Step 10: Environment-Specific Values

Create values-prod.yaml:

replicaCount: 10

image:
  tag: "1.0.0"

resources:
  requests:
    memory: "512Mi"
    cpu: "200m"
  limits:
    memory: "1Gi"
    cpu: "1000m"

autoscaling:
  enabled: true
  maxReplicas: 30

config:
  logLevel: ERROR
  environment: production

Deploy with prod values:

helm install my-app ./myapp-chart -f values-prod.yaml

# Verify
kubectl get deployment my-app-api
# Should have 10 replicas

Validation

# Release exists and is deployed
helm list
# my-app should be DEPLOYED

# Pods running with correct image
kubectl get pods -o jsonpath='{.items[*].spec.containers[0].image}'
# Should show YOUR_USERNAME/myapp:1.0.0

# Service created
kubectl get svc my-app-api

# Upgrade worked
helm history my-app
# Should show multiple revisions

Challenge (Optional)

Add chart dependencies:

Create requirements.yaml (Helm 2) or Chart.yaml (Helm 3):

dependencies:
- name: postgresql
  version: "11.x.x"
  repository: https://charts.bitnami.com/bitnami
  condition: postgresql.enabled

# Update dependencies
helm dependency update ./myapp-chart

# Now your chart includes PostgreSQL
helm install my-app ./myapp-chart \
  --set postgresql.enabled=true \
  --set postgresql.auth.password=mysecret

Cleanup

helm uninstall my-app
rm -rf myapp-chart/

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Next: Lab 07: Multi-Region Setup