feat(router): support for custom router function

Author: chimurai

CHANGELOG.md

@@ -1,10 +1,11 @@
 # Changelog
 
 ## [develop](https://github.com/chimurai/http-proxy-middleware/releases/tag/v0.16.0)
-- feat(router): deprecate and renamed `proxyTable` option to `router`
+- feat(router): support for custom `router` function.
+- feat(router): deprecate and renamed `proxyTable` option to `router`.
 
 ## [v0.15.2](https://github.com/chimurai/http-proxy-middleware/releases/tag/v0.15.2)
-- fix(websocket): fixes websocket upgrade
+- fix(websocket): fixes websocket upgrade.
 
 ## [v0.15.1](https://github.com/chimurai/http-proxy-middleware/releases/tag/v0.15.1)
 - feat(pathRewrite): expose `req` object to pathRewrite function.

lib/index.js

@@ -71,36 +71,39 @@ function HttpProxyMiddleware(context, opts) {
     function prepareProxyRequest(req) {
         // store uri before it gets rewritten for logging
         var originalPath = req.url;
+        var newProxyOptions = _.cloneDeep(proxyOptions);
 
         // Apply in order:
         // 1. option.router
         // 2. option.pathRewrite
-        var alteredProxyOptions = __applyRouterOption(req, proxyOptions);
-        __applyPathRewrite(pathRewriter, req);
+        __applyRouter(req, newProxyOptions);
+        __applyPathRewrite(req, pathRewriter);
 
         // debug logging for both http(s) and websockets
         if (proxyOptions.logLevel === 'debug') {
-            var arrow = getArrow(originalPath, req.url, proxyOptions.target, alteredProxyOptions.target);
-            logger.debug('[HPM] %s %s %s %s', req.method, originalPath, arrow, alteredProxyOptions.target);
+            var arrow = getArrow(originalPath, req.url, proxyOptions.target, newProxyOptions.target);
+            logger.debug('[HPM] %s %s %s %s', req.method, originalPath, arrow, newProxyOptions.target);
         }
 
-        return alteredProxyOptions;
+        return newProxyOptions;
     }
 
     // Modify option.target when router present.
-    // return altered options
-    function __applyRouterOption(req) {
-        var result = proxyOptions;
+    function __applyRouter(req, options) {
+        var newTarget;
 
-        if (proxyOptions.router) {
-            result = Router.createProxyOptions(req, proxyOptions);
-        }
+        if (options.router) {
+            newTarget = Router.getTarget(req, options);
 
-        return result;
+            if (newTarget) {
+                logger.debug('[HPM] Router new target: %s -> "%s"', options.target, newTarget);
+                options.target = newTarget;
+            }
+        }
     }
 
     // rewrite path
-    function __applyPathRewrite(pathRewriter, req) {
+    function __applyPathRewrite(req, pathRewriter) {
         if (pathRewriter) {
             var path = pathRewriter(req.url, req);
 

lib/router.js

@@ -2,44 +2,42 @@ var _      = require('lodash');
 var logger = require('./logger.js').getInstance();
 
 module.exports = {
-    createProxyOptions: createProxyOptions
+    getTarget: getTarget
 };
 
-function createProxyOptions(req, config) {
+function getTarget(req, config) {
+    var newTarget;
     var router = config.router;
-    var result = _.clone(config);
 
-    if (router) {
-        var newTarget = getTargetFromProxyTable(req, router);
-        if (newTarget) {
-            logger.debug('[HPM] router new target: %s -> "%s"', config.target, newTarget);
-            result = _.assign(result, {target: newTarget});    // override option.target
-        }
+    if (_.isPlainObject(router)) {
+        newTarget = getTargetFromProxyTable(req, router);
+    } else if (_.isFunction(router)) {
+        newTarget = router(req);
     }
 
-    return result;
+    return newTarget;
 }
 
-function getTargetFromProxyTable(req, router) {
+function getTargetFromProxyTable(req, table) {
     var result;
     var host = req.headers.host;
     var path = req.url;
 
     var hostAndPath = host + path;
 
-    _.forIn(router, function(value, key) {
+    _.forIn(table, function(value, key) {
         if (containsPath(key)) {
 
             if (hostAndPath.indexOf(key) > -1) {    // match 'localhost:3000/api'
-                result = router[key];
-                logger.debug('[HPM] router match: %s -> "%s"', hostAndPath, result);
+                result = table[key];
+                logger.debug('[HPM] Router table match: "%s"', key);
                 return false;
             }
         } else {
 
             if (key === host) {                     // match 'localhost:3000'
-                result = router[key];
-                logger.debug('[HPM] router match: %s -> "%s"', host, result);
+                result = table[key];
+                logger.debug('[HPM] Router table match: "%s"', host);
                 return false;
             }
 

test/unit/router.spec.js

@@ -2,26 +2,52 @@ var expect = require('chai').expect;
 var router = require('./_libs').router;
 
 describe('router unit test', function() {
+    var req, config, result;
 
-    describe('router.createProxyOptions', function() {
-        var req, config, result;
+    beforeEach(function() {
+        req = {
+            headers: {
+                host: 'localhost'
+            },
+            url: '/'
+        };
 
-        beforeEach(function() {
-            req = {
-                headers: {
-                    host: 'localhost'
-                },
-                url: '/'
-            };
+        config = {
+            target: 'http://localhost:6000'
+        };
+
+    });
 
-            config = {
+    describe('router.getTarget from function', function() {
+        var request;
+
+        beforeEach(function() {
+            proxyOptionWithRouter = {
                 target: 'http://localhost:6000',
-                changeOrigin: true                 // other options should be returned, such as changeOrigin
+                router: function(req) {
+                    request = req;
+                    return 'http://foobar.com:666';
+                }
             };
 
-            configProxyTable = {
+            result = router.getTarget(req, proxyOptionWithRouter);
+        });
+
+        describe('custom dynamic router function', function() {
+            it('should provide the request object for dynamic routing', function() {
+                expect(request.headers.host).to.equal('localhost');
+                expect(request.url).to.equal('/');
+            });
+            it('should return new target', function() {
+                expect(result).to.equal('http://foobar.com:666');
+            });
+        });
+    });
+
+    describe('router.getTarget from table', function() {
+        beforeEach(function() {
+            proxyOptionWithRouter = {
                 target: 'http://localhost:6000',
-                changeOrigin: true,                // other options should be returned, such as changeOrigin
                 router: {
                     'alpha.localhost': 'http://localhost:6001',
                     'beta.localhost': 'http://localhost:6002',
@@ -36,84 +62,72 @@ describe('router unit test', function() {
 
         describe('without router config', function() {
             it('should return the normal target when router not present in config', function() {
-                result = router.createProxyOptions(req, config);
-                expect(result.target).to.equal('http://localhost:6000');
-                expect(result).not.to.equal(config);            // should return cloned object
-                expect(result).to.deep.equal(config);           // clone content should match
-                expect(result.changeOrigin).to.be.true;
+                result = router.getTarget(req, config);
+                expect(result).to.equal(undefined);
             });
         });
 
         describe('with just the host in router config', function() {
             it('should target http://localhost:6001 when for router:"alpha.localhost"', function() {
                 req.headers.host = 'alpha.localhost';
-                result = router.createProxyOptions(req, configProxyTable);
-                expect(result.target).to.equal('http://localhost:6001');
-                expect(result.changeOrigin).to.be.true;
+                result = router.getTarget(req, proxyOptionWithRouter);
+                expect(result).to.equal('http://localhost:6001');
             });
 
             it('should target http://localhost:6002 when for router:"beta.localhost"', function() {
                 req.headers.host = 'beta.localhost';
-                result = router.createProxyOptions(req, configProxyTable);
-                expect(result.target).to.equal('http://localhost:6002');
-                expect(result.changeOrigin).to.be.true;
+                result = router.getTarget(req, proxyOptionWithRouter);
+                expect(result).to.equal('http://localhost:6002');
             });
         });
 
         describe('with host and host + path config', function() {
             it('should target http://localhost:6004 without path', function() {
                 req.headers.host = 'gamma.localhost';
-                result = router.createProxyOptions(req, configProxyTable);
-                expect(result.target).to.equal('http://localhost:6004');
-                expect(result.changeOrigin).to.be.true;
+                result = router.getTarget(req, proxyOptionWithRouter);
+                expect(result).to.equal('http://localhost:6004');
             });
 
             it('should target http://localhost:6003 exact path match', function() {
                 req.headers.host = 'gamma.localhost';
                 req.url = '/api';
-                result = router.createProxyOptions(req, configProxyTable);
-                expect(result.target).to.equal('http://localhost:6003');
-                expect(result.changeOrigin).to.be.true;
+                result = router.getTarget(req, proxyOptionWithRouter);
+                expect(result).to.equal('http://localhost:6003');
             });
 
             it('should target http://localhost:6004 when contains path', function() {
                 req.headers.host = 'gamma.localhost';
                 req.url = '/api/books/123';
-                result = router.createProxyOptions(req, configProxyTable);
-                expect(result.target).to.equal('http://localhost:6003');
-                expect(result.changeOrigin).to.be.true;
+                result = router.getTarget(req, proxyOptionWithRouter);
+                expect(result).to.equal('http://localhost:6003');
             });
         });
 
         describe('with just the path', function() {
             it('should target http://localhost:6005 with just a path as router config', function() {
                 req.url = '/rest';
-                result = router.createProxyOptions(req, configProxyTable);
-                expect(result.target).to.equal('http://localhost:6005');
-                expect(result.changeOrigin).to.be.true;
+                result = router.getTarget(req, proxyOptionWithRouter);
+                expect(result).to.equal('http://localhost:6005');
             });
 
             it('should target http://localhost:6005 with just a path as router config', function() {
                 req.url = '/rest/deep/path';
-                result = router.createProxyOptions(req, configProxyTable);
-                expect(result.target).to.equal('http://localhost:6005');
-                expect(result.changeOrigin).to.be.true;
+                result = router.getTarget(req, proxyOptionWithRouter);
+                expect(result).to.equal('http://localhost:6005');
             });
 
             it('should target http://localhost:6000 path in not present in router config', function() {
                 req.url = '/unknow-path';
-                result = router.createProxyOptions(req, configProxyTable);
-                expect(result.target).to.equal('http://localhost:6000');
-                expect(result.changeOrigin).to.be.true;
+                result = router.getTarget(req, proxyOptionWithRouter);
+                expect(result).to.equal(undefined);
             });
         });
 
         describe('matching order of router config', function() {
             it('should return first matching target when similar paths are configured', function() {
                 req.url = '/some/specific/path';
-                result = router.createProxyOptions(req, configProxyTable);
-                expect(result.target).to.equal('http://localhost:6006');
-                expect(result.changeOrigin).to.be.true;
+                result = router.getTarget(req, proxyOptionWithRouter);
+                expect(result).to.equal('http://localhost:6006');
             });
         });