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API Gateway (Gateway Service)

The Gateway Service is an API Gateway that runs within Watt (the Node.js Application Server). It automatically integrates multiple microservices into a unified API ecosystem, providing a single public endpoint for clients while managing routing, composition, and conflict resolution behind the scenes.

The Gateway Service aggregates APIs from multiple sources - whether they're other applications in your Watt application, external APIs, or legacy systems - presenting them as a cohesive, well-documented API to your clients.

For a high level overview of how Watt and its applications work, please reference the Overview guide.

Features​

  • Service Discovery: Automatically discover and compose APIs from multiple applications in your Watt application
  • OpenAPI Composition: Combine multiple OpenAPI specifications into a single, unified API documentation
  • GraphQL Federation: Aggregate GraphQL schemas from multiple applications with Apollo Federation support
  • Conflict Resolution: Intelligent handling of endpoint conflicts and path overlaps between applications
  • Route Prefixing: Organize APIs with automatic or custom path prefixing for each application
  • Dynamic Updates: Real-time schema updates when underlying applications change (in development mode)
  • Custom Logic: Extend with Fastify plugins for authentication, rate limiting, or request transformation

When to Use Gateway Service​

Gateway Service is ideal for:

  • Microservices Architecture: Present a unified API from multiple independent services
  • API Aggregation: Combine internal and external APIs into a single public interface
  • Legacy Integration: Gradually modernize by composing new and legacy APIs
  • Team Boundaries: Allow different teams to own applications while providing unified client experience
  • API Versioning: Manage different API versions while maintaining client compatibility
  • Client Simplification: Reduce client complexity by handling application discovery and routing

Quick Start​

Create a Gateway Service within a Watt application:

# Create a new Watt application
wattpm create my-gateway

# Add multiple applications to compose
# (This will prompt you through the application setup)
cd my-gateway

# Start in development mode
wattpm dev

Your Gateway Service will automatically discover other applications in your Watt application and create a unified API. Visit http://localhost:3042/documentation to see the composed API documentation.

For application-specific configuration and advanced usage, see the Configuration guide.

Command Line usage (CLI)​

When using Watt, @platformatic/gateway applications will make some additional commands available on the terminal.

All the commands will be prefixed by the application id. For instance, if your application id is main, then you will have the following commands available:

  • main:fetch-openapi-schemas: Fetch OpenAPI schemas from remote services.

Issues

If you run into a bug or have a suggestion for improvement, please raise an issue on GitHub or join our Discord feedback channel.