http-proxy-rules

http-proxy-rules is an add-on module to the node-http-proxy library. It lets you define a set of rules to translate matching routes to target routes that the reverse proxy service will talk to on the client's behalf.

Installation

npm install http-proxy-rules --save

Example Use Case

  var http = require('http'),
      httpProxy = require('http-proxy'),
      HttpProxyRules = require('http-proxy-rules');

  // Set up proxy rules instance
  var proxyRules = new HttpProxyRules({
    rules: {
      '.*/test': 'http://localhost:8080/cool', // Rule (1)
      '.*/test2/': 'http://localhost:8080/cool2/', // Rule (2)
      '/posts/([0-9]+)/comments/([0-9]+)': 'http://localhost:8080/p/$1/c/$2', // Rule (3)
      '/author/([0-9]+)/posts/([0-9]+)/': 'http://localhost:8080/a/$1/p/$2/' // Rule (4)
    },
    default: 'http://localhost:8080' // default target
  });

  // Create reverse proxy instance
  var proxy = httpProxy.createProxy();

  // Create http server that leverages reverse proxy instance
  // and proxy rules to proxy requests to different targets
  http.createServer(function(req, res) {

    // a match method is exposed on the proxy rules instance
    // to test a request to see if it matches against one of the specified rules
    var target = proxyRules.match(req);
    if (target) {
      return proxy.web(req, res, {
        target: target
      });
    }

    res.writeHead(500, { 'Content-Type': 'text/plain' });
    res.end('The request url and path did not match any of the listed rules!');
  }).listen(6010, cb);

Given the object we used to initialize the HttpProxyRules instance above, here are some examples of how sample url paths would be translated.

Options

You can initialize a new http-proxy-rules instance with the following options:

{
  rules: {}, // See notes below
  default: '' // (optional) if no rules matched, translate url path to specified default
}

The rules object contains a set of key-value pairs mapping a regex-supported url path to a target route. The module only tries to match the visited url path, and not the entire url, with a specified rule. The target route must include the protocol (e.g., http) and the FQDN. You can use capturing groups when constructing a rule key (e.g. '/posts/(\d+)/). In this case, $1 in the target path will be replaced with the value from the first capturing group, $2 with the second one, and so on. See the tests for examples of how incoming route url paths may be translated with the use of this module.

Other Notes

• (?:\\W|$) is appended to the end of the regex-supported url path, so that if there is a key like .*/test in the rules, the module matches paths /test, /test/, /test? but not /testing.
• As long as object keys continued to be ordered in V8, if there are multiple rules that match against a given url path, the module will pick the matching rule listed first for the translation.