fix: missing credentials file with config file (#3684)

Author: JadenSimon

.changes/next-release/bugfix-Credentials-c59044aa.json

@@ -0,0 +1,5 @@
+{
+  "type": "bugfix",
+  "category": "Credentials",
+  "description": "Do not require credentials file when loading region from config."
+}

lib/node_loader.js

@@ -98,7 +98,13 @@ AWS.util.update(AWS.Config.prototype.keys, {
       ];
       var iniLoader = AWS.util.iniLoader;
       while (!region && toCheck.length) {
-        var configFile = iniLoader.loadFrom(toCheck.shift());
+        var configFile = {};
+        var fileInfo = toCheck.shift();
+        try {
+          configFile = iniLoader.loadFrom(fileInfo);
+        } catch (err) {
+          if (fileInfo.isConfig) throw err;
+        }
         var profile = configFile[env.AWS_PROFILE || AWS.util.defaultProfile];
         region = profile && profile.region;
       }

test/config.spec.js

@@ -150,6 +150,20 @@ describe('AWS.Config', function() {
           var config = new AWS.Config();
           expect(config.region).to.equal('us-east-1');
         });
+
+        it('non-existent credentials file returns empty', function() {
+          process.env.AWS_SDK_LOAD_CONFIG = '1';
+          var mock = '[default]\nregion = us-west-2';
+          helpers.spyOn(AWS.util, 'readFileSync').andCallFake(function(path) {
+            if (path.match(/[\/\\]home[\/\\]user[\/\\].aws[\/\\]config/)) {
+              return mock;
+            } else {
+              throw new Error('File does not exist!');
+            }
+          });
+          var config = new AWS.Config();
+          expect(config.region).to.equal('us-west-2');
+        });
       });
     }