Container Orchestration with Kubernetes

Kubernetes has become the industry standard for container orchestration. Understanding its concepts is essential for modern backend engineering.

From Docker to Kubernetes

Docker containers package applications with their dependencies. Kubernetes orchestrates these containers across clusters, handling:

Scheduling - Where containers run
Scaling - How many replicas
Networking - How containers communicate
Storage - Persistent data management
Health - Automatic restarts and replacements

Core Concepts

Pods

The smallest deployable unit - one or more containers:

apiVersion: v1
kind: Pod
metadata:
  name: backend-api
spec:
  containers:
  - name: api
    image: myapp:v1.0
    ports:
    - containerPort: 8080

Deployments

Manage desired state for pods:

apiVersion: apps/v1
kind: Deployment
metadata:
  name: backend-api
spec:
  replicas: 3
  selector:
    matchLabels:
      app: backend
  template:
    metadata:
      labels:
        app: backend
    spec:
      containers:
      - name: api
        image: myapp:v1.0

Services

Expose pods to the network:

apiVersion: v1
kind: Service
metadata:
  name: backend-service
spec:
  selector:
    app: backend
  ports:
  - port: 80
    targetPort: 8080
  type: LoadBalancer

Production Patterns

ConfigMaps and Secrets

Externalize configuration:

apiVersion: v1
kind: ConfigMap
metadata:
  name: app-config
data:
  database.url: "jdbc:postgresql://db:5432/mydb"
  cache.ttl: "3600"

Health Checks

Liveness and readiness probes:

livenessProbe:
  httpGet:
    path: /health
    port: 8080
  initialDelaySeconds: 30
  periodSeconds: 10

Resource Limits

Prevent resource exhaustion:

resources:
  requests:
    memory: "256Mi"
    cpu: "500m"
  limits:
    memory: "512Mi"
    cpu: "1000m"

Observability

Prometheus - Metrics collection
Grafana - Visualization
Loki - Log aggregation
Jaeger - Distributed tracing

Conclusion

Kubernetes is complex but powerful. Start with basic concepts, then gradually adopt advanced patterns as your needs grow.