k8s-helm

Kubernetes & Helm Patterns

Helm Chart Structure

helm/chatkeep/
├── Chart.yaml
├── values.yaml
├── values-dev.yaml
├── values-prod.yaml
├── templates/
│   ├── _helpers.tpl
│   ├── deployment.yaml
│   ├── service.yaml
│   ├── ingress.yaml
│   ├── configmap.yaml
│   ├── secret.yaml
│   ├── hpa.yaml
│   └── serviceaccount.yaml
└── charts/           # Dependencies

Chart.yaml

apiVersion: v2
name: chatkeep
description: Chatkeep Telegram Bot Service
type: application
version: 1.0.0
appVersion: "1.0.0"

dependencies:
  - name: postgresql
    version: "12.x.x"
    repository: "https://charts.bitnami.com/bitnami"
    condition: postgresql.enabled

values.yaml

# Image configuration
image:
  repository: registry.example.com/chatkeep
  tag: latest
  pullPolicy: IfNotPresent

# Replica configuration
replicaCount: 2

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

# Service configuration
service:
  type: ClusterIP
  port: 80
  targetPort: 8080

# Ingress
ingress:
  enabled: true
  className: nginx
  annotations:
    cert-manager.io/cluster-issuer: letsencrypt-prod
  hosts:
    - host: chatkeep.example.com
      paths:
        - path: /
          pathType: Prefix
  tls:
    - secretName: chatkeep-tls
      hosts:
        - chatkeep.example.com

# Environment variables
env:
  SPRING_PROFILES_ACTIVE: k8s
  SERVER_PORT: "8080"

# Secrets (reference external secrets)
secrets:
  BOT_TOKEN:
    secretName: chatkeep-bot
    key: token
  DATABASE_URL:
    secretName: chatkeep-db-credentials
    key: url

# Health checks
health:
  livenessProbe:
    httpGet:
      path: /actuator/health/liveness
      port: 8080
    initialDelaySeconds: 30
    periodSeconds: 10
  readinessProbe:
    httpGet:
      path: /actuator/health/readiness
      port: 8080
    initialDelaySeconds: 10
    periodSeconds: 5

# Autoscaling
autoscaling:
  enabled: true
  minReplicas: 2
  maxReplicas: 10
  targetCPUUtilizationPercentage: 70

# PostgreSQL subchart
postgresql:
  enabled: false  # Use external database

Deployment Template

# templates/deployment.yaml
apiVersion: apps/v1
kind: Deployment
metadata:
  name: {{ include "chatkeep.fullname" . }}
  labels:
    {{- include "chatkeep.labels" . | nindent 4 }}
spec:
  {{- if not .Values.autoscaling.enabled }}
  replicas: {{ .Values.replicaCount }}
  {{- end }}
  selector:
    matchLabels:
      {{- include "chatkeep.selectorLabels" . | nindent 6 }}
  template:
    metadata:
      annotations:
        checksum/config: {{ include (print $.Template.BasePath "/configmap.yaml") . | sha256sum }}
      labels:
        {{- include "chatkeep.selectorLabels" . | nindent 8 }}
    spec:
      serviceAccountName: {{ include "chatkeep.serviceAccountName" . }}
      containers:
        - name: {{ .Chart.Name }}
          image: "{{ .Values.image.repository }}:{{ .Values.image.tag }}"
          imagePullPolicy: {{ .Values.image.pullPolicy }}
          ports:
            - name: http
              containerPort: {{ .Values.service.targetPort }}
              protocol: TCP
          env:
            {{- range $key, $value := .Values.env }}
            - name: {{ $key }}
              value: {{ $value | quote }}
            {{- end }}
            {{- range $key, $secret := .Values.secrets }}
            - name: {{ $key }}
              valueFrom:
                secretKeyRef:
                  name: {{ $secret.secretName }}
                  key: {{ $secret.key }}
            {{- end }}
          {{- with .Values.health.livenessProbe }}
          livenessProbe:
            {{- toYaml . | nindent 12 }}
          {{- end }}
          {{- with .Values.health.readinessProbe }}
          readinessProbe:
            {{- toYaml . | nindent 12 }}
          {{- end }}
          resources:
            {{- toYaml .Values.resources | nindent 12 }}

Service Template

# templates/service.yaml
apiVersion: v1
kind: Service
metadata:
  name: {{ include "chatkeep.fullname" . }}
  labels:
    {{- include "chatkeep.labels" . | nindent 4 }}
spec:
  type: {{ .Values.service.type }}
  ports:
    - port: {{ .Values.service.port }}
      targetPort: http
      protocol: TCP
      name: http
  selector:
    {{- include "chatkeep.selectorLabels" . | nindent 4 }}

ConfigMap Template

# templates/configmap.yaml
apiVersion: v1
kind: ConfigMap
metadata:
  name: {{ include "chatkeep.fullname" . }}-config
  labels:
    {{- include "chatkeep.labels" . | nindent 4 }}
data:
  application.yaml: |
    spring:
      profiles:
        active: k8s
    server:
      port: {{ .Values.service.targetPort }}
    management:
      endpoints:
        web:
          exposure:
            include: health,info,prometheus

Helper Templates

# templates/_helpers.tpl
{{- define "chatkeep.name" -}}
{{- default .Chart.Name .Values.nameOverride | trunc 63 | trimSuffix "-" }}
{{- end }}

{{- define "chatkeep.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 }}

{{- define "chatkeep.labels" -}}
helm.sh/chart: {{ .Chart.Name }}-{{ .Chart.Version }}
app.kubernetes.io/name: {{ include "chatkeep.name" . }}
app.kubernetes.io/instance: {{ .Release.Name }}
app.kubernetes.io/version: {{ .Chart.AppVersion | quote }}
app.kubernetes.io/managed-by: {{ .Release.Service }}
{{- end }}

{{- define "chatkeep.selectorLabels" -}}
app.kubernetes.io/name: {{ include "chatkeep.name" . }}
app.kubernetes.io/instance: {{ .Release.Name }}
{{- end }}

HorizontalPodAutoscaler

# templates/hpa.yaml
{{- if .Values.autoscaling.enabled }}
apiVersion: autoscaling/v2
kind: HorizontalPodAutoscaler
metadata:
  name: {{ include "chatkeep.fullname" . }}
  labels:
    {{- include "chatkeep.labels" . | nindent 4 }}
spec:
  scaleTargetRef:
    apiVersion: apps/v1
    kind: Deployment
    name: {{ include "chatkeep.fullname" . }}
  minReplicas: {{ .Values.autoscaling.minReplicas }}
  maxReplicas: {{ .Values.autoscaling.maxReplicas }}
  metrics:
    - type: Resource
      resource:
        name: cpu
        target:
          type: Utilization
          averageUtilization: {{ .Values.autoscaling.targetCPUUtilizationPercentage }}
{{- end }}

Helm Commands

# Install/Upgrade
helm upgrade --install chatkeep ./helm/chatkeep \
  -f ./helm/chatkeep/values-prod.yaml \
  --namespace chatkeep \
  --create-namespace

# Dry run
helm upgrade --install chatkeep ./helm/chatkeep \
  --dry-run --debug

# Template only (see generated YAML)
helm template chatkeep ./helm/chatkeep -f values-prod.yaml

# Lint chart
helm lint ./helm/chatkeep

# Rollback
helm rollback chatkeep 1 --namespace chatkeep

# History
helm history chatkeep --namespace chatkeep

# Uninstall
helm uninstall chatkeep --namespace chatkeep

kubectl Commands

# Get pods
kubectl get pods -n chatkeep -l app.kubernetes.io/name=chatkeep

# Logs
kubectl logs -n chatkeep -l app.kubernetes.io/name=chatkeep --tail=100 -f

# Describe deployment
kubectl describe deployment chatkeep -n chatkeep

# Port forward for local testing
kubectl port-forward -n chatkeep svc/chatkeep 8080:80

# Exec into pod
kubectl exec -it -n chatkeep deployment/chatkeep -- /bin/sh

# Apply manually
kubectl apply -f k8s/configmap.yaml -n chatkeep