Design Document:Data API Gateway

Data API Gateway

Technology: Kong, AWS API Gateway, or Azure API Management
Purpose: Unified interface for data access and ingestion
Features:
- Rate limiting and throttling
- Authentication and authorization
- API versioning and documentation
- Request/response transformation

Data API Gateway Design and Implementation

Here's a detailed, hands-on design for a Data API Gateway, a crucial component for providing a unified, secure, and controlled interface to your semiconductor manufacturing data.

1. Technology Selection

For an on-premises or private cloud deployment, Kong Gateway is the most suitable choice. While AWS and Azure API Gateways are powerful, they're tied to their respective cloud ecosystems and may not be a viable solution for a private deployment with stringent data residency requirements. Kong is an open-source, cloud-native gateway that offers excellent flexibility and a rich plugin ecosystem to implement all your required features.

2. Core Gateway Functionality

The Data API Gateway will act as the single entry point for all internal services and applications needing to access the unified data platform.

Reverse Proxy: The gateway will route incoming API requests to the appropriate backend service. For example, a request for /api/v1/lots/{lot_id}/history will be routed to a microservice that queries the ETL-processed data in your ClickHouse data warehouse.
Request/Response Transformation: The gateway can modify requests or responses on the fly. This is useful for:
- Data Masking: Hiding or obfuscating sensitive data fields in the response.
- Protocol Translation: Converting between different protocols if necessary.
- API Composition: Aggregating data from multiple backend services into a single response, which is a common pattern for creating "backend-for-frontend" APIs.

3. Key Features Implementation

A. Authentication and Authorization

Plugin: Use Kong's built-in JWT (JSON Web Token) plugin or an OpenID Connect (OIDC) plugin for robust authentication.
Workflow:
1. A user or internal service authenticates with your company's identity provider (e.g., Active Directory, Okta).
2. The identity provider issues a signed JWT containing user information and their permissions (e.g., role: data_analyst, access_level: restricted).
3. All subsequent API requests must include this JWT in the authorization header.
4. The Kong Gateway validates the JWT's signature and expiration. If valid, it inspects the token's claims (permissions) and determines if the user is authorized to access the requested endpoint. This ensures that a process engineer can't access equipment engineer-specific APIs without proper permission.

B. Rate Limiting and Throttling

Plugin: Use Kong's Rate Limiting plugin to control API traffic and prevent abuse or accidental overload.
Configuration:
- Burst Limiting: Configure a maximum number of requests allowed in a short period (e.g., 100 requests per minute per IP address). This prevents sudden spikes from impacting performance.
- Throttling: Apply different limits based on user roles or application. For example, a critical real-time monitoring service might have a higher limit than a less critical reporting tool. You can set limits based on consumer (user), IP, or service (backend).
Implementation: This is configured via Kong's Admin API. The following is an example of a rate-limiting policy applied to a service:

// Rate-limiting plugin configuration in Kong
{
  "name": "rate-limiting",
  "config": {
    "minute": 100,
    "limit_by": "ip"
  }
}

C. API Versioning and Documentation

Strategy: Use URI-based versioning (/api/v1/..., /api/v2/...). This is the most common and easily understood method.
Implementation:
- Create separate routes in Kong for each API version. Kong will then proxy requests to the correct version of the backend microservice.
- Swagger/OpenAPI: Use Swagger/OpenAPI to document all APIs. This provides a machine-readable specification of your API endpoints, data models, and authentication methods.
- Developer Portal: Kong provides a Developer Portal feature where you can automatically publish the OpenAPI documentation. This gives internal teams a single, up-to-date place to discover and understand all available APIs, fostering collaboration and self-service.
- Deprecation: When a new version is released, an older version (e.g., v1) can be marked as deprecated in the documentation. Kong allows you to monitor traffic to older versions and safely retire them once adoption of the new version is high.