1. Security & Data Sensitivity
1.1 Authentication
- JWT-based and/or session-based authentication:
- JWT:
- Short-lived access tokens.
- Long-lived refresh tokens (rotated; revocation list or versioning).
- Signed with asymmetric keys (RS256 / ES256).
- Session-based:
- HTTP-only, Secure, SameSite cookies.
- Server-side session store (Redis / DB-backed).
- JWT:
- Token storage guidelines:
- Never store access tokens in LocalStorage.
- Prefer HttpOnly cookies for refresh tokens.
- Token introspection and expiration validation mandatory.
1.2 Authorization (RBAC / ABAC)
- Role-Based Access Control (RBAC):
- Roles:
admin,user,support,system - Role-permission mapping at service boundaries.
- Roles:
- Attribute-Based Access Control (ABAC) for contextual decisions:
- Examples: region, ownership, account tier, resource classification.
- Middleware enforcement:
- Authentication (is identity valid).
- Authorization (is action permitted).
- Permission checks at controller + service layer.
1.3 Data Sensitivity & Logging
- Sensitive data never logged:
- Passwords, tokens, secrets, PAN, Aadhaar, credit cards.
- Logs must:
- Mask PII fields.
- Redact secrets automatically.
- Centralized logging system:
- CloudWatch / ELK / Datadog / Azure Monitor.
- Log format:
- JSON structured logs.
- Include
timestamp,level,service,correlationId.
1.4 Audit Logs
- Capture for:
- Authentication events.
- User management changes.
- Data updates (financial / medical / business-critical).
- Audit log schema:
id,timestamp,actorId,actorType,action,
resourceType,resourceId,metadata,correlationId
- Append-only storage.
- Tamper evidence:
- Hash chains.
- Immutable storage (WORM, S3 Glacier Vault Lock).
1.5 Input Validation & Sanitization
- Enforce schema validation:
- Zod / Joi / Yup / JSON Schema
- Validation coverage:
- REST layer.
- Event / message consumers.
- Sanitization:
- SQL injection.
- XSS.
- Command injection.
- Validation errors:
- Clear.
- Structured.
- No stack traces.
1.6 Additional Security Controls
- Rate limiting per:
- IP / user / API key.
- Web Application Firewall (WAF).
- Secrets management:
- AWS Secrets Manager / Vault.
- TLS / HTTPS everywhere.
- HTTP security headers:
- HSTS
- CSP
- X-Frame-Options
- X-Content-Type-Options
- Supply-chain security:
- Dependency scanning.
- Container scanning.
2. Error Handling
2.1 Structured Error Model
- Error codes grouped by domain:
AUTH_INVALID_CREDENTIALS,AUTH_FORBIDDEN,USER_NOT_FOUNDVALIDATION_ERROR,RESOURCE_NOT_FOUND,CONFLICT,RATE_LIMIT_EXCEEDED, etc.
2.2 Backend Error Handling
- Centralized error middleware:
- Maps thrown errors (domain errors, validation errors, infrastructure errors) to HTTP status and error codes.
- Log:
- Full technical details (stack trace) only in server logs with correlation ID.
- Clients see:
- High-level reason + correlation ID to share with support.
3. Data Persistence
3.1 Schema
Common conventions:
- All tables:
id(UUID good for microservices and sharding or bigint sequence)created_at,updated_at(timestamps with time zone)- Soft-delete:
deleted_at(where appropriate)
- Foreign keys with
ON DELETE/ON UPDATEstrategies explicitly defined. - Indexes:
- Primary key + frequently queried columns.
- Composite indexes for common filters (e.g.
(patient_id, scheduled_at)).
3.2 Migrations & Seeds
- All schema changes defined via migrations (e.g.
prisma migrate,knex,sequelize,dbmate,golang-migrate,drizzle-kit). - Migrations:
- Forward-only in production (no manual DB changes).
- Reviewed & peer-approved.
- Seeds:
- Minimal seed data for local/staging (roles, test users, sample domain data).
- Avoid sensitive/real data in non-prod.
3.3 Data Integrity & Constraints
- Use database constraints:
NOT NULL,CHECK,UNIQUE,FOREIGN KEYinstead of relying only on application code.
- Consider:
- Multi-tenant schemas (schema-per-tenant, row-level security, or tenant_id columns).
- Row-level security (RLS) for strict domain isolation where applicable.
3.4 Backup & Disaster Recovery
- Automated backups with clear RPO/RTO targets.
- Regular restore drills on staging environment.
- If using cloud-managed:
- Enable automated backups, point-in-time restore, and multi-AZ.
4. Testing Requirements
4.1 Test Types
- Unit Tests
- Small, isolated, mocking dependencies (repositories, external APIs).
- Integration Tests
- Real DB (test schema).
- HTTP API tests, message consumer tests.
- End-to-End (E2E) (Recommended)
- Complete flow (frontend(optional) → backend → DB) in ephemeral environment.
- Critical user perspective scenarios.
- Contract Tests (Recommended for microservices)
- API compatibility between services (e.g. Pact).
4.2 Coverage Requirements
- Target 90%+ coverage:
- At least for:
- Domain services.
- Controllers.
- Critical flows (e.g. signup, login, payment/booking/appointment creation).
- At least for:
- Enforce coverage in CI:
- Build fails if coverage threshold not met.
4.3 Test Environment
- Use dockerized services:
- Database test instance.
- Optional: Redis, message broker.
- Use isolated databases per test run where possible (migrate on startup).
5. Microservice Architecture & Domain Separation
Can also be implemented as a “modular monolith” using the same patterns.
5.1 Domain Separation
- Split code by bounded contexts (domains), not technical layers:
/src /modules /auth /users /appointments /billing /shared /config /logging /observability /http /validation
- Each module contains:
controllers(HTTP handlers)services(application layer)repositories(data access)dtos(input/output contracts)entities/models(domain models)
5.2 Repository Pattern & DTOs
- Repository Pattern
- Interfaces:
UserRepository,AppointmentRepository, etc. - Implementations:
PostgresUserRepository, etc. - Allows swapping DB or mocking in tests.
- Interfaces:
- DTOs
- Explicit request/response models.
- Used at boundaries (controller ↔ service ↔ external systems).
- Validation schemas tightly coupled to DTOs.
5.3 Circuit Breaker for External APIs
- External integrations (e.g. Insurance, Payment, Third-party APIs):
- Use circuit breaker (e.g. in-house,
opossum, Envoy/Hystrix-style behavior). - Track:
- Failure rate threshold.
- Open/closed/half-open states.
- Fallback behavior (cached data, queued retry, graceful degradation).
- Use circuit breaker (e.g. in-house,
5.4 Config Management & Correlation IDs
- Configuration:
- Typed config module loading from env variables.
- Validation of configuration at startup (Zod/Joi).
- Correlation IDs:
- Generated at edge (API Gateway or first service).
- Propagated across:
- HTTP headers (
X-Correlation-Id). - Logs, traces, error responses.
- HTTP headers (
5.5 Graceful Shutdown
- On termination signals (
SIGINT,SIGTERM):- Stop accepting new requests.
- Wait for in-flight requests to finish (with timeout).
- Close DB connections and message consumers.
- Flush logs and traces.
6. Observability & KPIs
6.1 OpenTelemetry Instrumentation
- Use OpenTelemetry for:
- Traces (spans per request, DB call, external call).
- Metrics (latency, error counts, queue depth, etc.).
- Logs (structured, correlation ID + trace ID).
6.2 Core KPIs
- API KPIs
- API latency (p95, p99) per route.
- Request throughput (RPS).
- Error rates (4xx/5xx).
- Database KPIs
- Query latency per statement/group.
- Slow query count.
- Connection pool utilization.
- Resilience KPIs
- Circuit breaker state changes.
- Retry counts.
- Queue backlog.
6.3 Distributed Tracing
- End-to-end tracing for critical flows:
- Example: Appointment/Order/Booking creation:
- Frontend → API Gateway → Backend service(s) → DB → external APIs.
- Example: Appointment/Order/Booking creation:
- Ensure:
- Trace context propagation via HTTP headers (
traceparent). - Each service automatically instruments incoming/outgoing requests and DB calls.
- Trace context propagation via HTTP headers (
6.4 Alerting & SLOs
- Define SLOs (e.g. 99.9% availability, p95 latency < X ms).
- Alerts for breaches:
- High error rate.
- Increased latency.
- Circuit breakers stuck open.
- DB CPU/connection saturation.
7. API Design & Documentation
7.1 OpenAPI 3.0
- Maintain a full OpenAPI 3.0 spec:
- Request/response schemas.
- Error models.
- Security schemes (JWT/cookie).
- Pagination/filters.
- Spec generated via:
- Code-first (decorators) OR
- Schema-first (OpenAPI as single source of truth).
7.2 Examples & Error Models
- Include example requests/responses for:
- Success paths.
- Typical error paths (validation, auth, not found).
- Error schema aligns with structured error model (Section 2).
7.3 Developer Portal / API Explorer
- Integrate:
- Swagger UI or ReDoc for internal/external usage.
- Protected in non-public scenarios (auth required to view).
7.4 API Versioning
- Versioned APIs:
- Path-based (
/v1,/v2) or header-based. - Deprecation policy and sunset timelines.
- Path-based (
8. CI/CD Requirements
8.1 CI: GitHub Actions
Workflows (example):
-
lint-and-test.yml- Steps:
- Install dependencies (with lockfile).
- Run linters (ESLint, Prettier).
- Run unit + integration tests.
- Enforce coverage threshold (90%+).
- Steps:
-
build-and-docker.yml- Steps:
- Build backend and frontend.
- Run type-checking (
tsc). - Build Docker images (backend, frontend, migrations).
- Push images to container registry.
- Steps:
-
Security & Quality (Recommended)
- Dependency scanning (npm audit, Snyk).
- Docker image scanning.
- Static analysis (SonarQube, CodeQL).
8.2 CD: Deployment
- Target: EC2/ECS/EKS/Kubernetes or similar.
- Deployment strategy:
- Blue-Green or Rolling deployments.
- Health checks and readiness probes.
- Zero-downtime DB migrations strategy (online migrations).
- Pipeline stages:
dev: auto-deploy on merge todevelop.staging: deploy on tagged commits, run smoke/E2E tests.prod: manual approval + canary rollout.
9. Documentation Requirements (README & Docs)
9.1 README Structure
Recommended sections:
-
Project Overview
- Short description of the system.
- Main features and business context.
-
Architecture Overview
- System diagram.
- Services and their responsibilities.
- Tech stack (languages, frameworks, infra).
-
Setup & Local Development
- Prerequisites (Node, Docker, etc.).
- Environment variables & sample
.env.example. - Commands:
npm run dev,npm run test,npm run lint.docker-compose up, etc.
-
Configuration & Environments
- How config is loaded & validated.
- Environment-specific behavior.
-
Security & Domain-Specific Considerations
- Sensitive data handling.
- Compliance/regulatory notes (e.g. HIPAA/GDPR/PCI if applicable).
- Authentication & authorization overview.
-
Testing Strategy
- Types of tests.
- How to run them locally.
- Coverage expectations.
-
CI/CD Pipeline
- Description of CI workflows.
- CD steps & deployment targets.
- How to promote builds between environments.
-
Observability & Monitoring
- Logging & tracing setup (OpenTelemetry).
- Metrics dashboards (Grafana/Datadog/etc.).
- Alerting & SLOs.
-
Operations & Runbooks (Link/Section)
- Common operational tasks (restart service, run migrations).
- How to handle incidents.
- On-call responsibilities.
-
Contribution Guidelines
- Branching strategy.
- Code style guidelines.
- PR template & review process.
11. Additional Recommended Production Concerns
11.1 Performance & Scalability
- Horizontal scalability for stateless services via ECS/EKS/K8s.
- DB connection pooling & query optimization.
- Caching strategy:
- Application-level caching (Redis/memory).
- HTTP caching headers for frontend APIs.
11.2 Messaging & Async Processing
- Use message queues (Kafka/SQS/RabbitMQ) for:
- Email notifications.
- Long-running tasks.
- Third-party API integrations that must be resilient.
11.3 Feature Flags
- Feature toggle system (LaunchDarkly, ConfigCat, custom).
- Allows:
- Gradual rollouts.
- A/B testing.
- Safe emergency disable.
11.4 Compliance & Data Governance (If Applicable)
- GDPR/CCPA support:
- Data access/export/delete flows.
- PII minimization & encryption at rest + in transit.
- Data retention policies & anonymization.
12. Summary
This blueprint defines a generic, production-grade architecture with:
- Strong security and data protection.
- Clear error handling and domain separation.
- Robust data persistence with migrations and audit logs.
- Comprehensive testing and strict coverage enforcement.
- Modern microservice/modular design with circuit breakers and graceful shutdown.
- Full observability via OpenTelemetry and KPIs.
- First-class API documentation via OpenAPI + Swagger/ReDoc.
- A secure, performant Next.js frontend.
- CI/CD pipelines ready for automation and safe deployments.
- Detailed documentation expectations for corporate environments.
- Additional best practices for performance, scalability, compliance, and operations.
Adapt entity names and domain-specific rules (e.g. healthcare, finance, e-commerce) as needed, while keeping these architectural principles as the foundation.