Kubernetes for Developers: Getting Started

As a developer, understanding Kubernetes can significantly improve your deployment workflows. This guide covers the essentials you need to know.

Core Concepts

Pods

The smallest deployable unit in Kubernetes:

apiVersion: v1
kind: Pod
metadata:
  name: my-app
spec:
  containers:
    - name: app
      image: my-app: 1.0.0
      ports:
        - containerPort: 3000

Deployments

Manage replicas and rolling updates:

apiVersion: apps/v1
kind: Deployment
metadata:
  name: my-app
spec:
  replicas: 3
  selector:
    matchLabels:
      app: my-app
  template:
    metadata:
      labels:
        app: my-app
    spec:
      containers:
        - name: app
          image: my-app: 1.0.0
          ports:
            - containerPort: 3000
          resources:
            requests:
              memory: "128Mi"
              cpu: "100m"
            limits:
              memory: "256Mi"
              cpu: "200m"

Services

Expose your application:

apiVersion: v1
kind: Service
metadata:
  name: my-app-service
spec:
  selector:
    app: my-app
  ports:
    - port: 80
      targetPort: 3000
  type: ClusterIP

Health Checks

Always implement liveness and readiness probes:

livenessProbe:
  httpGet:
    path: /health
    port: 3000
  initialDelaySeconds: 10
  periodSeconds: 10

readinessProbe:
  httpGet:
    path: /ready
    port: 3000
  initialDelaySeconds: 5
  periodSeconds: 5

ConfigMaps and Secrets

apiVersion: v1
kind: ConfigMap
metadata:
  name: app-config
data:
  DATABASE_HOST: "postgres.default.svc.cluster.local"
  LOG_LEVEL: "info"
---
apiVersion: v1
kind: Secret
metadata:
  name: app-secrets
type: Opaque
data:
  DATABASE_PASSWORD: cGFzc3dvcmQxMjM=  # base64 encoded

Kubernetes has a steep learning curve, but mastering it will make you a more effective developer in modern cloud environments.