@isomorphic-git/cors-proxy

This is the software running on https://cors.isomorphic-git.org/ - a free service (generously sponsored by Clever Cloud) for users of isomorphic-git that enables cloning and pushing repos in the browser.

It is derived from https://github.com/wmhilton/cors-buster with added restrictions to reduce the opportunity to abuse the proxy. Namely, it blocks requests that don't look like valid git requests.

Installation

npm install @isomorphic-git/cors-proxy

CLI usage

Start proxy on default port 9999:

cors-proxy run

Start proxy on a custom port:

cors-proxy run -p 9889

Start proxy in daemon mode.

cors-proxy start

Kill the daemon process:

cors-proxy stop

CLI configuration

Environment variables:

• PORT the port to listen to (if run with npm start)
• ALLOW_ORIGIN the value for the 'Access-Control-Allow-Origin' CORS header
• INSECURE_HTTP_ORIGINS comma separated list of origins for which HTTP should be used instead of HTTPS (added to make developing against locally running git servers easier)

Middleware usage

You can also use the cors-proxy as a middleware in your own server.

import express from 'express';
import corsProxy from '@isomorphic-git/cors-proxy';

const app = express();
const options = {};

app.use(corsProxy(options));

Middleware configuration

The middleware doesn't use the environment variables. The options object supports the following properties:

• origin: string. The value for the 'Access-Control-Allow-Origin' CORS header
• insecure_origins: string[]. Array of origins for which HTTP should be used instead of HTTPS (added to make developing against locally running git servers easier)
• authorization: (req, res, next) => void. A middleware function you can use to handle custom authorization. Is run after filtering for git-like requests and handling CORS but before the request is proxied.

Example:

app.use(
  corsProxy({
    authorization: (req: Request, res: Response, next: NextFunction) => {
      // proxied git HTTP requests already use the Authorization header for git credentials,
      // so their [Company] credentials are inserted in the X-Authorization header instead.
      if (getAuthorizedUser(req, 'X-Authorization')) {
        return next();
      } else {
        return res.status(401).send("Unable to authenticate you with [Company]'s git proxy");
      }
    },
  }),
);

// Only requests with a valid JSON Web Token will be proxied
function getAuthorizedUser(req: Request, header: string = 'Authorization') {
  const Authorization = req.get(header);

  if (Authorization) {
    const token = Authorization.replace('Bearer ', '');
    try {
      const verifiedToken = verify(token, env.APP_SECRET) as IToken;
      if (verifiedToken) {
        return {
          id: verifiedToken.userId,
        };
      }
    } catch (e) {
      // noop
    }
  }
}

Installation on Kubernetes

There is no official chart for this project, helm or otherwise. You can make your own, but keep in mind cors-proxy uses the Micro server, which will return a 403 error for any requests that do not have the user agent header.

Example:

containers:
  - name: cors-proxy
    image: node:lts-alpine
    env:
      - name: ALLOW_ORIGIN
        value: https://mydomain.com
    command:
      - npx
    args:
      - '@isomorphic-git/cors-proxy'
      - start
    ports:
      - containerPort: 9999
        hostPort: 9999
        name: proxy
        protocol: TCP
    livenessProbe:
      tcpSocket:
        port: proxy
    readinessProbe:
      tcpSocket:
        port: proxy

License

This work is released under The MIT License