feat(logging): add error description when logging errors.

lib/index.js

@@ -1,5 +1,6 @@
 var _              = require('lodash');
 var httpProxy      = require('http-proxy');
+var errno          = require('errno');
 var configFactory  = require('./config-factory');
 var handlers       = require('./handlers');
 var contextMatcher = require('./context-matcher');
@@ -128,9 +129,14 @@ function HttpProxyMiddleware(context, opts) {
     }
 
     function logError(err, req, res) {
-        var hostname = (req.hostname || req.host) || (req.headers && req.headers.host); // (node0.10 || node 4/5) || (websocket)
-        var targetUri = (proxyOptions.target.host || proxyOptions.target) + req.url;
-
-        logger.error('[HPM] PROXY ERROR: %s. %s -> %s', err.code, hostname, targetUri);
+        var hostname = (req.headers && req.headers.host) || (req.hostname || req.host); // (websocket) || (node0.10 || node 4/5)
+        var target = proxyOptions.target.host || proxyOptions.target;
+        var description =  errno.code[err.code] && errno.code[err.code].description;    //  description for the error code
+
+        if (description) {
+            logger.error('[HPM] Error \'%s\' (ErrorCode=%s) occurred while trying to proxy request %s from %s to %s', description, err.code, req.url, hostname, target);
+        } else {
+            logger.error('[HPM] Error (ErrorCode=%s) occurred while trying to proxy request %s from %s to %s', err.code, req.url, hostname, target);
+        }
     }
 };

package.json

@@ -51,6 +51,7 @@
     "http-proxy": "^1.14.0",
     "is-glob": "^2.0.1",
     "lodash": "^4.14.2",
-    "micromatch": "^2.3.11"
+    "micromatch": "^2.3.11",
+    "errno": "^0.1.4"
   }
 }