Merge pull request #250 from stanley-cheung/add_php_google_auth_example

Add PHP Google Auth example

grpc-auth-support.md

@@ -174,3 +174,24 @@ if (authorization.IsCreateScopedRequired)
 var client = new Greeter.GreeterClient(channel,
         new StubConfiguration(OAuth2InterceptorFactory.Create(credential)));
 ```
+
+###Authenticating with Google (PHP)
+```php
+// Base case - No encryption/authorization
+$client = new helloworld\GreeterClient(
+  new Grpc\BaseStub('localhost:50051', []));
+...
+
+// Authenticating with Google
+// the environment variable "GOOGLE_APPLICATION_CREDENTIALS" needs to be set
+$scope = "https://www.googleapis.com/auth/grpc-testing";
+$auth = Google\Auth\ApplicationDefaultCredentials::getCredentials($scope);
+$opts = [
+  'credentials' => Grpc\Credentials::createSsl(file_get_contents('ca.pem'));
+  'update_metadata' => $auth->getUpdateMetadataFunc(),
+];
+
+$client = new helloworld\GreeterClient(
+  new Grpc\BaseStub('localhost:50051', $opts));
+
+```

php/composer.json

@@ -11,6 +11,7 @@
   "require": {
     "php": ">=5.5.0",
     "datto/protobuf-php": "dev-master",
+    "google/auth": "dev-master",
     "grpc/grpc": "dev-master"
   }
 }