What Is Microservices?

How Microservices Works

An e-commerce monolith has one codebase for users, orders, payments, and inventory. In microservices: each is a separate service with its own database. Deploy the payment service without touching inventory. Scale the order service independently during sales. If the recommendation service crashes, checkout still works.

Microservices add complexity: distributed transactions, network latency, service discovery, observability across services. Start with a monolith, extract services only when you have a clear reason — team boundaries, scaling needs, or deployment independence.

Why Developers Use Microservices

Microservices solve organizational problems (multiple teams working independently) and scaling problems (scale individual services). They don't solve code quality problems. A bad monolith becomes bad microservices plus a distributed systems headache.

Key Concepts

• Service Boundaries — Each microservice owns a specific business capability and its data — users, orders, payments
• Independent Deployment — Deploy, scale, and update services independently — no coordinated releases
• API Communication — Services communicate via HTTP/REST, gRPC, or message queues — no shared databases
• Data Isolation — Each service owns its database — no direct database queries between services
• Service Discovery — How services find each other — DNS, service registries (Consul), or platform-native (Kubernetes)
• Distributed Tracing — Track requests across multiple services — Jaeger, Zipkin, OpenTelemetry

Kubernetes Microservice Deployment

apiVersion: apps/v1
kind: Deployment
metadata:
  name: order-service
spec:
  replicas: 3
  selector:
    matchLabels:
      app: order-service
  template:
    spec:
      containers:
      - name: order-service
        image: myapp/order-service:v2.1
        ports:
        - containerPort: 8080
        env:
        - name: DATABASE_URL
          valueFrom:
            secretKeyRef:
              name: order-db-secret
              key: url

Frequently Asked Questions