gcp-function-proxy

A private HTTP/HTTPS proxy server built with Google Cloud Functions and TypeScript. Forward and route HTTP requests securely through GCP serverless infrastructure with API key authentication.

How It Works

Client ──▶ Cloud Function (auth + header filtering) ──▶ Target Server
  ◀──────────────── response forwarded back ◀──────────────────

The client sends a request with:

• X-API-Key — authentication header
• X-Target-Host — the upstream server to proxy to (e.g. https://api.example.com)

The function validates auth, strips internal headers, forwards the request to the target, and returns the response.

Project Structure

├── src/
│   └── index.ts        # Cloud Function entry point
├── dist/               # Compiled JS (generated)
├── package.json
├── tsconfig.json
└── .env.example

Environment Variables

Variable	Description
API_KEY	Secret key that clients must send in X-API-Key

Local Development

# Install dependencies
npm install

# Build & run locally (port 8080)
API_KEY=your-secret-key npm start

Deployment

npm run build

gcloud functions deploy proxy \
  --runtime nodejs22 \
  --trigger-http \
  --allow-unauthenticated \
  --entry-point proxy \
  --source . \
  --set-env-vars API_KEY=your-secret-key \
  --region us-central1 \
  --no-gen2

Note: --allow-unauthenticated permits public HTTP access — authentication is handled at the application level via the X-API-Key header. For an additional layer, remove this flag and use GCP IAM.

Usage

# GET request
curl -X GET \
  -H "X-API-Key: your-secret-key" \
  -H "X-Target-Host: https://httpbin.org" \
  https://YOUR_FUNCTION_URL/get

# POST request with JSON body
curl -X POST \
  -H "X-API-Key: your-secret-key" \
  -H "X-Target-Host: https://httpbin.org" \
  -H "Content-Type: application/json" \
  -d '{"key": "value"}' \
  https://YOUR_FUNCTION_URL/post

Error Responses

Status	Meaning
401	Missing or invalid X-API-Key
400	Missing or invalid X-Target-Host
502	Could not reach the upstream server

License

MIT