Adds filtered logging URL to php72 logging sample (GoogleCloudPlatform#941)

* fixes cs

Author: bshaffer

appengine/php72/logging/index.php

@@ -1,4 +1,5 @@
 <?php
+
 /**
  * Copyright 2018 Google Inc.
  *
@@ -26,6 +27,28 @@
 $logger->warning('This will show up as log level WARNING');
 $logger->error('This will show up as log level ERROR');
 
+// Create the proper filter to view the logs in Stackdriver
+$projectId = getenv('GOOGLE_CLOUD_PROJECT');
+$moduleId = getenv('GAE_SERVICE');
+$versionId = getenv('GAE_VERSION');
+
+$resource = sprintf(
+    'gae_app/module_id/%s/version_id/%s',
+    $moduleId,
+    $versionId
+);
+$logName = sprintf('projects/%s/logs/app', $projectId);
+
+$url = sprintf(
+    'https://console.cloud.google.com/logs/viewer?resource=%s&logName=%s',
+    urlencode($resource),
+    urlencode($logName)
+);
+
 ?>
 
-Logged INFO, WARNING, and ERROR log levels. Visit console.cloud.google.com/logs to see them
+<p>Logged INFO, WARNING, and ERROR log levels. Visit the URL below to see them:</p>
+
+<p><a href="<?= $url ?>"><?= $url ?></a></p>
+
+<?php phpinfo() ?>