Merge pull request #110 from murgatroid99/node_auth_info

Added Node auth example

grpc-auth-support.md

@@ -116,3 +116,24 @@ stub = Helloworld::Greeter::Stub.new('localhost:50051',
                                      creds: creds,
                                      update_metadata: authorization.updater_proc)
 ```
+
+###Authenticating with Google (Node.js)
+
+```node
+// Base case - No encryption/authorization
+var stub = new helloworld.Greeter('localhost:50051');
+...
+// Authenticating with Google
+var GoogleAuth = require('google-auth-library'); // from https://www.npmjs.com/package/google-auth-library
+...
+var creds = grpc.Credentials.createSsl(load_certs); // load_certs typically loads a CA roots file
+var scope = 'https://www.googleapis.com/auth/grpc-testing';
+(new GoogleAuth()).getApplicationDefault(function(err, auth) {
+  if (auth.createScopeRequired()) {
+    auth = auth.createScoped(scope);
+  }
+  var stub = new helloworld.Greeter('localhost:50051',
+                                    {credentials: creds},
+                                    grpc.getGoogleAuthDelegate(auth));
+});
+```