API Gateway — Deep Dive

graph TD
    M[Mobile] --> GW[API Gateway]
    W[Web] --> GW
    P[Partner] --> GW
    GW --> O[Order Service]
    GW --> U[User Service]
    GW --> PAY[Payment Service]

routes:
  - path: /api/orders/**
    service: order-service
  - path: /api/users/**
    service: user-service
  - path: /api/products/**
    service: product-service

routes:
  - headers:
      X-API-Version: v2
    service: order-service-v2
  - headers:
      X-API-Version: v1
    service: order-service-v1

routes:
  - path: /api/orders/**
    targets:
      - service: order-service-v1
        weight: 90
      - service: order-service-v2
        weight: 10

sequenceDiagram
    participant C as Client
    participant GW as API Gateway
    participant AS as Auth Server
    participant S as Service

    C->>GW: Request + JWT
    GW->>GW: Validate JWT signature
    GW->>GW: Check expiry, issuer, audience
    alt Invalid
        GW->>C: 401 Unauthorized
    else Valid
        GW->>S: Request + X-User-Id header
        S->>GW: Response
        GW->>C: Response
    end

plugins:
  - name: jwt
    config:
      claims_to_verify:
        - exp
      key_claim_name: kid
      secret_is_base64: false
  - name: request-transformer
    config:
      add:
        headers:
          - X-User-Id:$(jwt.claims.sub)

HTTP/1.1 429 Too Many Requests
Retry-After: 30
X-RateLimit-Limit: 100
X-RateLimit-Remaining: 0
X-RateLimit-Reset: 1699900000

plugins:
  - name: rate-limiting
    config:
      minute: 100
      hour: 1000
      policy: redis
      redis_host: redis

plugins:
  - name: request-transformer
    config:
      add:
        headers:
          - X-Request-ID:$(uuid)
          - X-Forwarded-Host:$(host)
      remove:
        headers:
          - X-Internal-Header

plugins:
  - name: proxy-cache
    config:
      strategy: memory
      content_type:
        - application/json
      cache_ttl: 300
      cache_control: true

sequenceDiagram
    participant C as Client
    participant GW as API Gateway
    participant OS as Order Service
    participant US as User Service
    participant PS as Product Service

    C->>GW: GET /dashboard
    par Parallel
        GW->>OS: GET /orders
        GW->>US: GET /profile
        GW->>PS: GET /recommendations
    end
    OS->>GW: Orders
    US->>GW: Profile
    PS->>GW: Recommendations
    GW->>GW: Aggregate
    GW->>C: Combined dashboard

graph TD
    C[Clients] --> GW[API Gateway]
    GW --> S1[Service 1]
    GW --> S2[Service 2]
    GW --> S3[Service 3]

graph TD
    subgraph US Region
        C1[Clients] --> GW1[Gateway US]
    end
    subgraph EU Region
        C2[Clients] --> GW2[Gateway EU]
    end
    GW1 --> Services
    GW2 --> Services

graph TD
    C[Clients] --> R[Router/LB]
    R --> GW1[Orders Gateway]
    R --> GW2[Users Gateway]
    R --> GW3[Products Gateway]
    GW1 --> OS[Order Services]
    GW2 --> US[User Services]
    GW3 --> PS[Product Services]