couchproxy-express.js

var http = require('http'),
    url = require('url');
PROXY_VIA = 'CouchProxy';

function debug(str){
   console.log(str);
}

exports.proxy = function(backendUrl){
   var backend = url.parse(backendUrl);
   debug('setup proxy for: ' + backendUrl);
   return function(req, res, next){
      debug('>>> ' + req.method + ' ' + req.url);
      var db = http.createClient(backend.port, backend.hostname);
      var body = null;
      // send a request body
      if( req.method == 'POST' || req.method == 'PUT' ){
         body = JSON.stringify(req.body);
         req.headers['content-length'] = body.length;
      }
      var proxy = db.request(req.method, req.url, req.headers);
      if( body ){
         debug(body);
         proxy.write(body);
      }
      proxy.end();

      // connection error
      proxy.connection.on('error', function(err){
         debug('error: ' + err);
         res.writeHead(503, {
            'Content-Type': 'application/json',
            'via': PROXY_VIA
         });
         if( req.method != 'HEAD' ){
            res.write(JSON.stringify({
               'error' : 'service temporary unavailable',
               'reason' : 'No database found.'
            }));
         }
         res.end('\n');
      });

      // get a response
      proxy.on('response', function(response){
         debug('<<<');
         response.headers['via'] = PROXY_VIA;
         res.writeHead(response.statusCode, response.headers);
         response.on('data', function(chunk){
            debug(chunk);
            if( req.method != 'HEAD' ){
               res.write(chunk, 'binary');
            }
         });
         response.on('end', function(){
            res.end();
         });
      });
   };
};