Google Cloud Vision API on PHP AppEngine
<p>I have been using the Google Cloud Vision api with a php app hosted on a private VPS for a while without issue.  I'm migrating the app to Google AppEngine and am now running into issues.</p>

<p>I'm using a CURL post to the API, but it's failing on AppEngine.  I have billing enabled and other curl requests work without issue.  Someone mentioned that calls to googleapis.com won't work on AppEngine, that I need to access the API differently.  I'm not able to find any resources online to confirm that.</p>

<p>Below is my code, CURL error #7 is returned, failed to connect to host.</p>

<pre><code>$request_json = '{
            "requests": [
                {
                  "image": {
                    "source": {
                        "gcsImageUri":"gs://bucketname/image.jpg"
                    }
                  },
                  "features": [
                      {
                        "type": "LABEL_DETECTION",
                        "maxResults": 200
                      }
                  ]
                }
            ]
        }';
$curl = curl_init();
curl_setopt($curl, CURLOPT_URL, 'https://vision.googleapis.com/v1/images:annotate?key='.GOOGLE_CLOUD_VISION_KEY);
curl_setopt($curl, CURLOPT_RETURNTRANSFER, true);
curl_setopt($curl, CURLOPT_HTTPHEADER, array('Content-type: application/json'));
curl_setopt($curl, CURLOPT_POST, true);
curl_setopt($curl, CURLOPT_POSTFIELDS, $request_json);
$json_response = curl_exec($curl);
$status = curl_getinfo($curl, CURLINFO_HTTP_CODE);
if ($status != 200) {
    die("Error: $status, response $json_response, curl_error " . curl_error($curl) . ', curl_errno ' . curl_errno($curl));
}
curl_close($curl);
echo '&lt;pre&gt;';
echo $json_response;
echo '&lt;/pre&gt;';
</code></pre>