Babbly API Gateway

The central entry point for all client requests to the Babbly social media platform, routing requests to appropriate microservices using YARP (Yet Another Reverse Proxy).

Tech Stack

• Backend: ASP.NET Core 9.0
• Reverse Proxy: YARP (Yet Another Reverse Proxy)
• Authentication: Auth0 JWT validation
• Monitoring: Prometheus metrics, Health checks

Features

• Service routing to backend microservices
• JWT token validation via Auth0
• User claims forwarding to downstream services
• CORS configuration for frontend access
• Health checks for all backend services
• Rate limiting per endpoint
• Request/response aggregation for complex queries

Local Development Setup

Prerequisites

• .NET SDK 9.0 or later
• All backend microservices running (or Docker Compose)
• Auth0 account configured

Installation

1. Clone the repository:

   git clone https://github.com/yourusername/babbly-api-gateway.git
   cd babbly-api-gateway

2. Restore dependencies:

   dotnet restore

3. Configure Auth0 settings in appsettings.json or via environment variables:

   # Using environment variables
   export AUTH0_DOMAIN=your-tenant.auth0.com
   export AUTH0_AUDIENCE=https://api.babbly.com

4. Run the gateway:

   dotnet run

The API Gateway will be available at http://localhost:5010.

Environment Variables

Variable	Description	Default
AUTH0_DOMAIN	Your Auth0 tenant domain	-
AUTH0_AUDIENCE	Auth0 API audience identifier	https://api.babbly.com
ASPNETCORE_URLS	URLs the gateway listens on	http://0.0.0.0:8080

Service Routing

The API Gateway routes requests to the following services:

Route Pattern	Target Service	Port
/api/auth/*	Auth Service	5001
/api/users/*	User Service	8081
/api/posts/*	Post Service	8080
/api/comments/*	Comment Service	8082
/api/likes/*	Like Service	8083

Special Endpoints

• /api/feed - Aggregated feed (posts with comments and likes)
• /api/profiles/id/{userId} - User profile by ID
• /api/profiles/username/{username} - User profile by username
• /health - Gateway health check
• /metrics - Prometheus metrics (development only)

Docker Support

Run with Docker Compose (recommended for local development):

# From the root of the Babbly organization
docker-compose up -d

This starts the API Gateway along with all backend services and infrastructure.

The gateway will be accessible at http://localhost:5010.

Architecture Notes

Request Flow

1. Client sends request to API Gateway
2. Gateway validates JWT token (if required)
3. Gateway extracts user claims from token
4. Gateway forwards request to appropriate microservice with user claims as headers
5. Microservice processes request using forwarded user context
6. Gateway returns response to client

User Claims Forwarding

The gateway extracts these claims from JWT tokens and forwards them as HTTP headers:

• X-User-Id: User's Auth0 ID
• X-User-Roles: User's roles (comma-separated)
• X-User-Email: User's email address
• X-User-Name: User's display name

This allows microservices to access user information without validating tokens themselves.

Health Checks

The gateway monitors backend service health and automatically routes around unhealthy instances.

Health check configuration:

• Interval: 10 seconds
• Timeout: 5 seconds
• Policy: Consecutive failures

YARP Configuration

Routes and clusters are defined in appsettings.json under the ReverseProxy section. The configuration is loaded at startup and can be hot-reloaded during development.

Rate Limiting

Rate limits are enforced per endpoint:

• /api/feed*: 60 requests/minute
• /api/comments*: 100 requests/minute
• /api/likes*: 30 requests/minute
• /api/users*: 50 requests/minute
• /api/auth*: 100 requests/minute

License

This project is licensed under the MIT License - see the LICENSE file for details.