A lightweight CORS (Cross-Origin Resource Sharing) proxy for the Unsloth Studio API. It runs as a local HTTP server that adds the required Access-Control-* headers, allowing browser-based frontends to call the Unsloth backend without being blocked by the browser's Same-Origin Policy.

Features

Zero dependencies — uses only Python 3 standard library modules.
POST proxy — forwards POST requests with Content-Type and Authorization headers intact.
CORS preflight — responds to OPTIONS requests with 204 No Content.
Health check — GET /health returns 200 OK with the current upstream target.
Systemd unit — drop-in service file for easy deployment on Linux.
Hardened — includes Linux security best practices in the unit file (no-new-privileges, strict system protection, minimal capabilities).

Installation

Requirements

Python 3.10+
sudo access (for systemd deployment)

Manual run

# Clone the repo
git clone https://github.com/NikkeDoy/CORSProxy.git
cd CORSProxy

# Run interactively
python main.py

systemd deployment

# Copy the service file
sudo cp services/corsproxy.service /etc/systemd/system/

# Reload systemd and enable the service
sudo systemctl daemon-reload
sudo systemctl enable corsproxy.service

# Start the service
sudo systemctl start corsproxy.service

# Verify it's running
sudo systemctl status corsproxy.service

Configuration

Command-line arguments

Argument	Default	Description
`--target HOST:PORT`	`127.0.0.1:8888`	Upstream Unsloth Studio address
`--listen PORT`	`8080`	Port the proxy listens on

Examples

# Default: listen :8080, forward to :8888 on localhost
python main.py

# Custom upstream port
python main.py --target 127.0.0.1:8000

# Custom listen port
python main.py --listen 9090

# Remote upstream
python main.py --target 10.0.0.5:8000 --listen 9090

Environment variables (systemd)

The service file exposes three tunable environment variables that you can override by editing the [Service] section:

Variable	Default	Description
`TARGET_HOST`	`127.0.0.1`	Upstream host
`TARGET_PORT`	`8888`	Upstream port
`LISTEN_PORT`	`8080`	Local listen port

To override without editing the unit file:

sudo systemctl set-environment TARGET_HOST=10.0.0.5 LISTEN_PORT=9090
sudo systemctl restart corsproxy.service

Endpoints

Method	Path	Description
`POST`	`/*`	Forwarded to the upstream server
`OPTIONS`	`/*`	Returns `204 No Content` with CORS headers
`GET`	`/health`	Returns `{"status":"ok","proxy_to":"host:port"}`
`GET`	`/*`	Any other path returns `405 Method Not Allowed`

Health check

Verify the proxy is running:

curl http://127.0.0.1:8080/health
# {"status": "ok", "proxy_to": "127.0.0.1:8888"}

Architecture

┌──────────┐          ┌────────────────┐          ┌──────────────┐
│ Browser  │ ───────► │ CORS Proxy     │ ───────► │ Unsloth API  │
│ (origin) │          │ (port 8080)    │ (port 8888)│ (upstream) │
└──────────┘          └────────────────┘          └──────────────┘

The proxy sits between the browser and the Unsloth Studio API, injecting the necessary CORS headers so the browser's Same-Origin Policy does not block cross-origin requests.

Project structure

CORSProxy/
├── main.py                  # Proxy application (entry point)
├── services/
│   └── corsproxy.service    # systemd unit file
├── tests/                   # Test suite (TDD)
├── docs/                    # Additional documentation
├── .gitignore              # Files to exclude from version control
└── LICENSE                 # MIT License

License

MIT License — see LICENSE for details.