Getting Started with Helm and Kubernetes

Helm is a package manager for Kubernetes applications that simplifies the process of defining, installing, and upgrading even the most complex Kubernetes applications. It provides a way to package, share, and manage applications and their dependencies in a consistent way. This tutorial will guide you through the basics of Helm and how to use it with Kubernetes.

Let’s create a simple Helm chart with examples of Chart.yaml, values.yaml, and template files.

1. Create a Helm Chart

# Create a new Helm chart named "mywebapp"
helm create mywebapp
cd mywebapp

2. Update Chart.yaml

Edit the Chart.yaml file to define metadata for your chart:

# mywebapp/Chart.yaml

apiVersion: v2
name: mywebapp
description: A Helm chart for deploying a simple web application
version: 0.1.0

3. Update values.yaml

Define default values for your chart in the values.yaml file:

# mywebapp/values.yaml

replicaCount: 1

image:
  repository: nginx
  tag: stable
  pullPolicy: IfNotPresent

service:
  type: ClusterIP
  port: 80

ingress:
  enabled: false
  hosts:
    - host: chart-example.local
      paths:
        - /

4. Create Template Files

Edit the template files in the templates directory:

Deployment Template (templates/deployment.yaml)

# mywebapp/templates/deployment.yaml

apiVersion: apps/v1
kind: Deployment
metadata:
  name: {{ include "mywebapp.fullname" . }}
  labels:
    app: {{ include "mywebapp.name" . }}
spec:
  replicas: {{ .Values.replicaCount }}
  selector:
    matchLabels:
      app: {{ include "mywebapp.name" . }}
  template:
    metadata:
      labels:
        app: {{ include "mywebapp.name" . }}
    spec:
      containers:
        - name: {{ .Chart.Name }}
          image: "{{ .Values.image.repository }}:{{ .Values.image.tag }}"
          imagePullPolicy: {{ .Values.image.pullPolicy }}
          ports:
            - containerPort: 80

Service Template (templates/service.yaml)

# mywebapp/templates/service.yaml

apiVersion: v1
kind: Service
metadata:
  name: {{ include "mywebapp.fullname" . }}
  labels:
    app: {{ include "mywebapp.name" . }}
spec:
  ports:
    - port: {{ .Values.service.port }}
      targetPort: 80
  selector:
    app: {{ include "mywebapp.name" . }}

Ingress Template (templates/ingress.yaml)

# mywebapp/templates/ingress.yaml

{{- if .Values.ingress.enabled -}}
apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
  name: {{ include "mywebapp.fullname" . }}
  annotations:
    nginx.ingress.kubernetes.io/rewrite-target: /
spec:
  rules:
    - host: {{ .Values.ingress.hosts.host }}
      http:
        paths:
          - path: {{ .Values.ingress.hosts.paths | quote }}
            pathType: Prefix
            backend:
              service:
                name: {{ include "mywebapp.fullname" . }}
                port:
                  number: {{ .Values.service.port }}
{{- end }}

5. Install the Helm Chart

# Install the chart with release name "mywebapp-release"
helm install mywebapp-release ./mywebapp

6. Upgrade the Helm Chart

# Upgrade the chart with a new image tag
helm upgrade mywebapp-release ./mywebapp --set image.tag=latest

7. Uninstall the Helm Chart

# Uninstall the chart
helm uninstall mywebapp-release

Feel free to customize the template files and values according to your application’s requirements. This example demonstrates a basic structure for a Helm chart with deployment, service, and optional ingress components.