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intermediate Phase · Observability

Health Checks

Implement health check endpoints for load balancers and orchestrators.

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Health Checks

Spring Boot Actuator

management.endpoints.web.exposure.include=health,info,metrics
management.endpoint.health.show-details=when-authorized

Custom Health Indicator

@Component
public class DatabaseHealthIndicator implements HealthIndicator {
    @Autowired
    private DataSource dataSource;

    @Override
    public Health health() {
        try (Connection conn = dataSource.getConnection()) {
            return Health.up().withDetail("database", "accessible").build();
        } catch (SQLException e) {
            return Health.down().withDetail("database", e.getMessage()).build();
        }
    }
}

Best Practices

Key Principles

  1. Follow SOLID principles
  2. Write clean, readable code
  3. Test thoroughly
  4. Document decisions
  5. Monitor in production

Implementation

  • Start simple, refactor as needed
  • Use established patterns
  • Consider trade-offs
  • Review with peers

Continuous Improvement

  • Learn from incidents
  • Update documentation
  • Share knowledge
  • Mentor others

Key Points

  • Understanding Health Checks is essential for production systems
  • Always consider scalability and maintainability
  • Test thoroughly before deploying to production
  • Monitor performance and set up alerting

Common Patterns

  1. Validation: Always validate input at the boundary
  2. Error Handling: Use structured error responses
  3. Logging: Log key events for debugging
  4. Testing: Unit, integration, and load tests
  5. Documentation: Keep docs updated with code changes

Practice Problems

0 / 3 solved
Implement Health Checks

Design and implement a solution for Health Checks in a backend system. Consider scalability, error handling, and production readiness.

Solution 
// Health Checks implementation
// Key aspects: validation, error handling, logging, testing

public class HealthChecks {
    // Production-ready implementation
}
Health Checks Edge Cases

Identify and handle edge cases for Health Checks. What happens under high load, with invalid input, or during failures?

Solution 
// Edge case handling:
// 1. Null/empty input -> validation
// 2. High load -> rate limiting, queuing
// 3. Failures -> retries, circuit breaker
// 4. Concurrent access -> locks, idempotency
Health Checks Testing Strategy

Write a testing strategy for Health Checks. Include unit tests, integration tests, and performance tests.

Solution 
// Test plan:
// - Unit: 80% coverage target
// - Integration: API contracts
// - Performance: latency, throughput
// - Chaos: failure injection

Quiz

1. Health check endpoint in Spring Boot?

Question 1 options

2. HealthIndicator returns?

Question 2 options

3. What is a common mistake when implementing Health Checks?

Question 3 options

Flashcards

Question

Health check endpoint?

Click to reveal answer

Answer

/actuator/health

Question

HealthIndicator returns?

Click to reveal answer

Answer

Health object (UP/DOWN)

Question

Health Checks best practices

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Answer

Follow SOLID principles, write clean code, test thoroughly, document decisions, and monitor in production.

Revision Notes

Key Takeaways

  • 1. Actuator provides /actuator/health
  • 2. Custom HealthIndicator for dependencies
  • 3. Returns UP or DOWN with details
  • 4. Used by load balancers and orchestrators

Interview Tips

  • • Implement health checks
  • • Use Actuator

Cheat Sheet

Health Checks

  • Endpoint: /actuator/health
  • Custom: implement HealthIndicator
  • Returns: Health.up() or Health.down()
  • Used by: load balancers, Kubernetes