@quatrain/gateway-upstream-express

A plug-and-play Express router designed to integrate any Express application with @quatrain/api-gateway.

This package exposes a dedicated /media/:uid endpoint designed for secure, internal infrastructure communication. It abstracts away security and protocol validation, allowing the upstream API to focus solely on resolving media file locations.

Usage

import express from 'express'
import { createGatewayRouter } from '@quatrain/gateway-upstream-express'

const app = express()

// Mount the gateway router under a dedicated internal prefix
app.use('/internal', createGatewayRouter({
  secret: process.env.GATEWAY_SECRET || 'your-shared-secret',
  onResolveMedia: async (req, uid, action) => {
    // 1. Validate if the request/user has access
    // 2. Resolve the media URL (e.g., from S3)
    
    return {
      url: 'https://s3.amazonaws.com/my-bucket/media.jpg',
      size: 1048576, // optional
      mimeType: 'image/jpeg' // optional
    }
  }
}))

Security

This endpoint is protected by a shared secret (GATEWAY_SECRET). The Gateway will automatically append this secret in the Authorization: Bearer <secret> header when proxying media requests.

Documentation

For a detailed explanation of the architecture, the sequence of operations, and a diagram of the workflow, please refer to the How-To Guide.