Gateway

The Gateway is the API gateway for the backend. It acts as a reverse proxy, providing a single entry point for all client requests and routing them to the appropriate microservice. It also handles several cross-cutting concerns.

Responsibilities

• Request Routing: Routes incoming requests to the correct microservice based on the URL path.
• Single Entry Point: Simplifies the client-side configuration by providing a single URL for all backend services.
• Security: Applies security middleware to all incoming requests.
• CORS: Handles Cross-Origin Resource Sharing (CORS) for the entire backend.
• Rate Limiting: Implements rate limiting to protect the backend services from abuse.
• Request Logging: Logs incoming requests for monitoring and debugging.
• Health Checks: Provides a /health endpoint to check the status of the gateway.

Middleware

The gateway uses several middleware from the @ce-sdr/shared package to handle cross-cutting concerns:

• securityMiddleware(): Applies various security headers.
• gatewayCors(): Configures CORS for allowed origins.
• rateLimiter(): Limits the number of requests per IP address.
• requestLogger("api-gateway"): Logs incoming requests with a "api-gateway" tag.
• healthCheck("api-gateway"): Provides a health check endpoint.
• notFoundHandler(): Handles requests to non-existent routes.
• errorHandler(): A centralized error handler.

Routing Flow

The following diagram illustrates how the gateway routes requests to the different backend services.

Routing Table

The gateway uses a path-based routing strategy. Here is the routing configuration based on apps/gateway/src/server.ts:

Path Prefix	Target Service	Target URL (from env)
/auth-service	Auth Service	AUTH_SERVICE_URL
/brand-service	Brand Service	BRAND_SERVICE_URL
/campaigns-service	Campaign Service	CAMPAIGNS_SERVICE_URL
/health	Gateway (itself)	-

Configuration

The URLs for the downstream services are configured via environment variables. For more details, please refer to the Configuration documentation.

Structure

The gateway is located in the apps/gateway directory.

apps/gateway
├── src
│   ├── index.ts
│   └── server.ts
├── package.json
├── tsconfig.json
└── turbo.json