updates memcache sample for env:flex memcache changes (GoogleCloudPlatform#258)

* updates memcache sample for env:flex memcache changes

Author: bshaffer

appengine/flexible/memcache/README.md

@@ -16,6 +16,9 @@ $ composer install
 **Prerequisites**
 
 - Install the [Google Cloud SDK](https://developers.google.com/cloud/sdk/).
+- Set up memcache using [Redis Labs Memcache Cloud][redis labs memcache].
+- edit `app.yaml` and update the environment variables for your Memcache
+  instance.
 
 **Deploy with gcloud**
 
@@ -33,4 +36,6 @@ $ curl http://{YOUR_PROJECT_ID}.appspot.com/memcached/a
 $ curl http://{YOUR_PROJECT_ID}.appspot.com/memcached/a -T hello.txt
 $ curl http://{YOUR_PROJECT_ID}.appspot.com/memcached/a
 hello
-```
+```
+
+[redis labs memcache]: https://cloud.google.com/appengine/docs/flexible/python/using-redislabs-memcache

appengine/flexible/memcache/app.php

@@ -26,9 +26,20 @@
 $app->register(new TwigServiceProvider());
 $app['twig.path'] = [ __DIR__ ];
 $app['memcached'] = function () {
-    $addr = getenv('MEMCACHE_PORT_11211_TCP_ADDR');
-    $port = (int) getenv('MEMCACHE_PORT_11211_TCP_PORT');
+    if (getenv('USE_GAE_MEMCACHE')) {
+        $addr = getenv('GAE_MEMCACHE_HOST') ?: 'localhost';
+        $port = getenv('GAE_MEMCACHE_PORT') ?: '11211';
+    } else {
+        $server = getenv('MEMCACHE_SERVER') ?: 'localhost:11211';
+        list($addr, $port) = explode(':', $server);
+    }
+    $username = getenv('MEMCACHE_USERNAME');
+    $password = getenv('MEMCACHE_PASSWORD');
     $memcached = new Memcached;
+    if ($username && $password) {
+        $memcached->setOption(Memcached::OPT_BINARY_PROTOCOL, true);
+        $memcached->setSaslAuthData($username, $password);
+    }
     if (!$memcached->addServer($addr, $port)) {
         throw new Exception("Failed to add server $addr:$port");
     }

appengine/flexible/memcache/app.yaml

@@ -2,4 +2,16 @@ runtime: php
 vm: true
 
 runtime_config:
-  document_root: web
+  document_root: web
+
+# [START env_variables]
+env_variables:
+  # If you are using the App Engine Memcache service (currently in alpha),
+  # uncomment this section and comment out the other Memcache variables.
+  # USE_GAE_MEMCACHE: 1
+  MEMCACHE_SERVER: your-memcache-server
+  # If you are using a Memcached server with SASL authentiation enabled,
+  # fill in these values with your username and password.
+  MEMCACHE_USERNAME: ""
+  MEMCACHE_PASSWORD: ""
+# [END env_variables]

appengine/flexible/memcache/composer.json

@@ -6,6 +6,7 @@
     "require-dev": {
         "gecko-packages/gecko-memcache-mock": "^2.0",
         "google/cloud-tools": "<=1.0",
+        "paragonie/random_compat": "^2.0",
         "guzzlehttp/guzzle": "^6.2",
         "monolog/monolog": "^1.19",
         "phpunit/phpunit": "~4"