节点快递代理中间件句柄重定向

Question

I am trying to use proxy-middleware to forward to https://npmcdn.com/ which works when I specify the final path, but when I specify shorthand urls, they are redirected to / of the local server, so return a 404.

app.use('/cdn', proxy('https://npmcdn.com/'));

Then trying to hit local server...

$.get('/cdn/lodash@4.9.0'); // works as expected
$.get('/cdn/lodash'); // is redirected to `/lodash@4.9.0` so gets 404

How can I handle redirects with my proxy server so that it is redirected to the correct remote url?

Update:

@hassansin, thanks for the pointer. It looks like I can fix my problem by adding a condition to handle when absolute path is given without domain, do you think it will break anything else?

if (((statusCode > 300 && statusCode < 304) || statusCode === 201) && location) {
    // absolute path with domain
    if(location.indexOf(options.href) > -1) {
      headers.location = location.replace(options.href, slashJoin('/', slashJoin((options.route || ''), '')));
    // absolute path without domain
    } else if(location[0] === '/') {
      headers.location = options.href.replace(/\/$/,'') + headers.location;
    }
}

Update 2:

@hassansin, how about this..?

    // absolute path without domain
    } else if(location[0] === '/' && req.originalUrl.slice(req.url.length*-1) === req.url) {
      headers.location = req.originalUrl.slice(0, req.url.length*-1) + headers.location;
    }

Answer 1

https://npmcdn.com/lodash redirects to https://npmcdn.com/lodash@4.9.0 with 302 status and location:/lodash@4.9.0 header. proxy-middleware doesn't seem to handle relative 302 redirects properly. It only handles absolute redirects .

Answer 2

This will include the baseUrl back on the redirect location

• /cdn/lodash will redirect to /lodash@4.9.0
  • userResHeaderDecorator will rewrite it to /cnd/lodash@4.9.0
• request to /cdn/lodash@4.9.0 will work properly

app.use(
  '/$BASEURL',
  proxy(`http://somewhere-else.com`, {
    userResHeaderDecorator(headers, userReq, userRes) {
      if (userRes.statusCode.toString().startsWith('30') 
        && !headers.location.includes('://'))
        headers.location = userReq.baseUrl + headers.location
      return headers
    },
  })
)