Microservices Best Practices (Simple & Interview-Ready)

What is a Microservice?

A microservice is a small, independent service that:

Does one business function
Has its own code, data, and deployment
Communicates with other services over network calls

1️⃣ Single Responsibility (One service = One business capability)

Best Practice

Each microservice should handle only one business responsibility.

Example

❌ UserService handling login + payments + reports
✅ AuthService, PaymentService, ReportService

Interview line

Each microservice should follow the Single Responsibility Principle.

2️⃣ Independent Deployment

Best Practice

A microservice must be deployable without impacting others.

Why?

Faster releases
Less risk
Better scalability

Interview line

Microservices should be independently deployable.

3️⃣ Database per Microservice

Best Practice

Each microservice should own its own database.

❌ Shared database
✅ Separate databases

Why?

Loose coupling
Independent scaling
Schema changes won’t break others

Interview line

Microservices should not share databases to avoid tight coupling.

4️⃣ Communication: Prefer Async Over Sync

Best Practice

Prefer asynchronous communication (Kafka, RabbitMQ)
Use sync (REST/gRPC) only when needed

Example

Order placed → Event published → Inventory updated

Interview line

Event-driven communication improves scalability and resilience.

5️⃣ API Design & Contracts

Best Practice

Use clear API contracts
Version APIs (/v1/orders)
Never break existing clients

Interview line

Microservices should expose well-defined, versioned APIs.

6️⃣ Fault Tolerance & Resilience

Best Practice

Assume network failures will happen.

Use:

Timeouts
Retries
Circuit Breakers

Example

If PaymentService is down, don’t crash OrderService.

Interview line

Microservices must be resilient to partial failures.

7️⃣ Observability (Logs, Metrics, Traces)

Best Practice

Every microservice should have:

Structured logs
Metrics (latency, error rate)
Distributed tracing

Why?

Debugging microservices without observability is impossible.

Interview line

Observability is critical for monitoring and debugging microservices.

8️⃣ Configuration Management

Best Practice

Externalize configuration
Do not hardcode values

Use:

ConfigMaps
Environment variables
Secret managers

Interview line

Configuration should be externalized and environment-specific.

9️⃣ Stateless Services

Best Practice

Microservices should be stateless.

Why?

Easy horizontal scaling
Better reliability

Interview line

Stateless services scale better and are easier to manage.

🔟 Service Discovery

Best Practice

Services should discover each other dynamically.

Tools

Kubernetes DNS
Service Mesh
Registry (Eureka, Consul)

Interview line

Service discovery avoids hardcoded service endpoints.

1️⃣1️⃣ Security Best Practices

Best Practice

Use authentication & authorization
Secure service-to-service calls
Rotate secrets

Interview line

Microservices should follow zero-trust security principles.

1️⃣2️⃣ Avoid Chatty Communication

Best Practice

Avoid many small synchronous calls
Prefer batching or async events

Interview line

Chatty communication increases latency and failure risk.

1️⃣3️⃣ Versioning & Backward Compatibility

Best Practice

Never break existing consumers
Add new fields instead of changing existing ones

Interview line

Backward compatibility is essential in microservice APIs.

1️⃣4️⃣ Use the Right Size (Not Too Small)

Best Practice

Avoid over-micro-servicing.

❌ One service per method
✅ One service per business domain

Interview line

Microservices should be sized around business domains, not technical functions.

1️⃣5️⃣ Start Simple, Then Split

Best Practice

Start with modular monolith
Split when scale or team size grows

Interview line

Microservices should be introduced when complexity justifies them.