return 504, 502 and 500 as appropriate Fixes chimurai#131 (chimurai#132)

Author: graingert

lib/handlers.js

@@ -48,9 +48,21 @@ function getProxyEventHandlers(opts) {
 
 function defaultErrorHandler(err, req, res) {
     var host = (req.headers && req.headers.host);
+    var code = err.code;
 
     if (res.writeHead && !res.headersSent) {
-        res.writeHead(500);
+        if (/HPE_INVALID/.test(code)) {
+            res.writeHead(502);
+        } else {
+            switch(code) {
+                case 'ECONNRESET':
+                case 'ENOTFOUND':
+                case 'ECONNREFUSED':
+                    res.writeHead(504);
+                    break;
+                default: res.writeHead(500);
+            }
+        }
     }
 
     res.end('Error occured while trying to proxy to: ' + host + req.url);

test/e2e/http-proxy-middleware.spec.js

@@ -395,7 +395,7 @@ describe('E2E http-proxy-middleware', function() {
                 });
 
                 it('should handle errors when host is not reachable', function() {
-                    expect(response.statusCode).to.equal(500);
+                    expect(response.statusCode).to.equal(504);
                 });
             });
 

test/unit/handlers.spec.js

@@ -101,9 +101,21 @@ describe('default proxy error handler', function() {
         errorMessage = undefined;
     });
 
-    it('should set the http status code to: 500', function() {
-        proxyError(mockError, mockReq, mockRes, proxyOptions);
-        expect(httpErrorCode).to.equal(500);
+    var codes = [
+      ['HPE_INVALID_FOO', 502],
+      ['HPE_INVALID_BAR', 502],
+      ['ECONNREFUSED', 504],
+      ['ENOTFOUND', 504],
+      ['ECONNREFUSED', 504],
+      ['any', 500],
+    ];
+    codes.forEach(function(item) {
+      var msg = item[0];
+      var code = item[1];
+      it('should set the http status code for ' + msg + ' to: ' + code, function() {
+        proxyError({ code: msg }, mockReq, mockRes, proxyOptions);
+        expect(httpErrorCode).to.equal(code);
+      });
     });
 
     it('should end the response and return error message', function() {