Proxy with express js

Question

To avoid same-domain AJAX issues  I want my node js web server to forward all requests from URL  api BLABLA to another server  for example other domain com 3000 BLABLA  and return to user the same thing that this remote server returned  transparently    All other URLs  beside  api    are to be served directly  no proxying   How do I achieve this with node js   express js  Can you give a simple code example    both the web server and the remote 3000 server are under my control  both running node js with express js     So far I found this https   github com http-party node-http-proxy   but reading the documentation there didn t make me any wiser  I ended up with  var proxy   new httpProxy RoutingProxy    app all   api     function req  res        console log  old request url     req url      req url         req url split      slice 2  join          remove the   api  part     console log  new request url     req url      proxy proxyRequest req  res            host   other domain com           port  3000               but nothing is returned to the original web server  or to the end user   so no luck

User · Answer

I don t have have an express sample  but one with plain http-proxy package  A very strip down version of the proxy I used for my blog   In short  all nodejs http proxy packages work at the http protocol level  not tcp socket  level  This is also true for express and all express middleware  None of them can do transparent proxy  nor NAT  which means keeping incoming traffic source IP in the packet sent to backend web server   However  web server can pickup original IP from http x-forwarded headers and add it into the log   The xfwd  true in proxyOption enable x-forward header feature for http-proxy   const url   require  url    const proxy   require  http-proxy     proxyConfig         httpPort  8888      proxyOptions            target                host   example com               port  80                    xfwd  true     lt --- This is what you are looking for            function startProxy          proxy          createServer proxyConfig proxyOptions           listen proxyConfig httpPort   0 0 0 0        startProxy      Reference for X-Forwarded Header  https   en wikipedia org wiki X-Forwarded-For  Full version of my proxy  https   github com J-Siu ghost-https-nodejs-proxy

User · Answer

To extend trigoman s answer  full credits to him  to work with POST  could also make work with PUT etc    app use   api   function req  res      var url    YOUR API BASE URL   req url    var r   null    if req method      POST          r   request post  uri  url  json  req body        else        r   request url          req pipe r  pipe res

User · Answer

I used the following setup to direct everything on  rest to my backend server  on port 8080   and all other requests to the frontend server  a webpack server on port 3001   It supports all HTTP-methods  doesn t lose any request meta-info and supports websockets  which I need for hot reloading       var express    require  express    var app        express    var httpProxy   require  http-proxy    var apiProxy   httpProxy createProxyServer    var backend    http   localhost 8080       frontend    http   localhost 3001    app all   rest     function req  res      apiProxy web req  res   target  backend         app all       function req  res        apiProxy web req  res   target  frontend         var server   require  http   createServer app   server on  upgrade   function  req  socket  head      apiProxy ws req  socket  head   target  frontend        server listen 3000

User · Answer

I found a shorter solution that does exactly what I want https   github com http-party node-http-proxy  After installing http-proxy  npm install http-proxy --save   Use it like below in your server index app js  var proxyServer   require  http-route-proxy    app use   api BLABLA    proxyServer connect     to   other domain com 3000 BLABLA     https  true    route               I really have spent days looking everywhere to avoid this issue  tried plenty of solutions and none of them worked but this one    Hope it is going to help someone else too

User · Answer

Ok  here s a ready-to-copy-paste answer using the require  request   npm module and an environment variable  instead of an hardcoded proxy    coffeescript  app use  req  res  next  - gt                                                     r   false   method   req method toLowerCase   replace  delete    del     switch method     when  get    post    del    put        r   request method           uri  process env PROXY URL   req url         json  req body      else       return res send  invalid method     req pipe r  pipe res   javascript   app use function req  res  next      var method  r    method   req method toLowerCase   replace  delete   del      switch  method        case  get       case  post       case  del       case  put         r   request method            uri  process env PROXY URL   req url          json  req body                 break      default        return res send  invalid method          return req pipe r  pipe res

User · Answer

First install express and http-proxy-middleware  npm install express http-proxy-middleware --save   Then in your server js  const express   require  express    const proxy   require  http-proxy-middleware     const app   express    app use express static  client         Add middleware for http proxying  const apiProxy   proxy   api     target   http   localhost 8080      app use   api   apiProxy       Render your site const renderIndex    req  res    gt      res sendFile path resolve   dirname   client index html       app get       renderIndex    app listen 3000       gt      console log  Listening on  http   localhost 3000          In this example we serve the site on port 3000  but when a request end with  api we redirect it to localhost 8080   http   localhost 3000 api login redirect to http   localhost 8080 api login

User · Answer

You want to use http request to create a similar request to the remote API and return its response   Something like this   const http   require  http       or use import http from  http        your app config here     app post   api BLABLA    oreq  ores    gt      const options            host to forward to     host   www google com          port to forward to     port  80         path to forward to     path    api BLABLA          request method     method   POST          headers to send     headers  oreq headers          const creq   http      request options  pres   gt             set encoding       pres setEncoding  utf8              set http status code based on proxied response       ores writeHead pres statusCode             wait for data       pres on  data   chunk   gt            ores write chunk                    pres on  close        gt               closed  let s end client request as well         ores end                     pres on  end        gt               finished  let s finish client request as well         ores end                          on  error   e   gt             we got an error       console log e message         try              attempt to set error message and http status         ores writeHead 500           ores write e message           catch  e               ignore               ores end               creq end          Notice  I haven t really tried the above  so it might contain parse errors hopefully this will give you a hint as to how to get it to work

User · Answer

request has been deprecated as of February 2020  I ll leave the answer below for historical reasons  but please consider moving to an alternative listed in this issue    Archive  I did something similar but I used request instead   var request   require  request    app get      function req res        modify the url in any way you want   var newurl    http   google com      request newurl  pipe res         I hope this helps  took me a while to realize that I could do this

User · Answer

I found a shorter and very straightforward solution which works seamlessly  and with authentication as well  using express-http-proxy  const url   require  url    const proxy   require  express-http-proxy        New hostname path as specified by question  const apiProxy   proxy  other domain com 3000 BLABLA         proxyReqPathResolver  req   gt  url parse req baseUrl  path      And then simply  app use   api     apiProxy    Note  as mentioned by  MaxPRafferty  use req originalUrl in place of baseUrl to preserve the querystring      forwardPath  req   gt  url parse req baseUrl  path  Update  As mentioned by Andrew  thank you    there s a ready-made solution using the same principle  npm i --save http-proxy-middleware  And then  const proxy   require  http-proxy-middleware   var apiProxy   proxy   api    target   http   www example org api     app use apiProxy   Documentation  http-proxy-middleware on Github I know I m late to join this party  but I hope this helps someone

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