moai-domain-backend

Monolithic architectures are simpler to deploy initially but become harder to scale; microservices enable independent scaling and team ownership but introduce operational complexity. Choose microservices when you need independent deployment, different tech stacks per service, or scaling of specific components. Start monolithic if your domain is new or team is small.

Observability combines monitoring, distributed tracing, and structured logging. Use Prometheus for metrics, OpenTelemetry for trace instrumentation across services, and centralized logging to correlate requests. This enables fast root-cause analysis when latency spikes or errors occur in production.

Design REST APIs with API gateway patterns to handle authentication and rate limiting, cache frequently accessed data, use database query optimization and indexes, and separate read/write concerns. Kubernetes deployment with auto-scaling ensures your infrastructure grows with demand.

Event-driven architecture decouples services and handles asynchronous workflows like background jobs and notifications. Use it when operations are independent, order matters but timing doesn't, or you need to process high-volume streams. Synchronous APIs work better for tightly coupled, request-response operations.

Implement authentication and authorization at the API gateway, use encrypted connections, validate all inputs, apply principle of least privilege, and monitor for anomalies. Separate security concerns by layer—client, API, service, and database—to prevent single points of failure.

Kubernetes manages containerized services with auto-scaling, rolling updates, and self-healing. Configure resource requests/limits, use health checks for reliability, and employ service meshes like Istio for traffic management and observability across your backend services.