Give some servers a bit more time to recover from a 502 response when…

… requesting HEAD + GET in close succession. Avoids 502 response to GET request. Fixes #120
Munter · Jul 16, 2017 · 1b2c80c · 1b2c80c
1 parent 27537f7
commit 1b2c80c
Showing 1 changed file with 17 additions and 6 deletions.
diff --git a/lib/index.js b/lib/index.js
@@ -149,10 +149,12 @@ module.exports = function (options) {
         }
     }
 
-    function httpStatus(url, relations, retryWithGetMethod) {
+    function httpStatus(url, relations, attempt) {
+        attempt = attempt || 1;
+
         return function (callback) {
             request({
-                method: retryWithGetMethod ? 'get' : 'head',
+                method: attempt === 1 ? 'head' : 'get',
                 url: url.replace(/#.*$/, ''),
                 strictSSL: true,
                 gzip: true,
@@ -170,8 +172,8 @@ module.exports = function (options) {
 
                     if (code) {
                         // Some servers send responses that request apparently handles badly when using the HEAD method...
-                        if (code === 'HPE_INVALID_CONSTANT' && !retryWithGetMethod) {
-                            return httpStatus(url, relations, true)(callback);
+                        if (code === 'HPE_INVALID_CONSTANT' && attempt === 1) {
+                            return httpStatus(url, relations, attempt + 1)(callback);
                         }
 
                         if (code === 'ENOTFOUND') {
@@ -187,8 +189,17 @@ module.exports = function (options) {
 
                     callback(undefined, status);
                 } else {
-                    if (!retryWithGetMethod && res.statusCode >= 400 && res.statusCode < 500) {
-                        return httpStatus(url, relations, true)(callback);
+                    // Some servers respond weirdly to HEAD requests. Make a second attempt with GET
+                    if (attempt === 1 && res.statusCode >= 400 && res.statusCode < 600) {
+                        return httpStatus(url, relations, attempt + 1)(callback);
+                    }
+
+                    // Some servers (jspm.io) respond with 502 if requesting HEAD, then GET to close in succession. Give the server a second to cool down
+                    if (attempt === 2 && res.statusCode >= 400 && res.statusCode < 600) {
+                        setTimeout(function () {
+                             httpStatus(url, relations, attempt + 1)(callback);
+                        }, 1000);
+                        return;
                     }
 
                     status = res.statusCode;