502 Error when accessing Google Data API

[Spokes]

I have a website with a form in which a user enters a URL of a youtube video. When the form is "submitted" (actually, an AJAX call is made, which updates the form), the part of the form that's updated via the AJAX call shows a "502 Bad Gateway nginx 1.8" error - this happens when attempting to get youtube data from Google's Youtube API, V3. The code that gets data from the google API is as follows:

def get_youtube_data_via_API(self, video_id, production = False):
    try:
        if production or self.settings.url in self.request.env.HTTP_HOST:  
            api_key = ... # production API Key
        else:        
            api_key= ... # testing API key
        # generate the API URL
        api_url = "https://www.googleapis.com/youtube/v3/videos?id=" + \
            str(video_id) + "&key=" + api_key + "&part=snippet"
        # get the data
        response = requests_get(api_url)
        return json_loads(response.text)
    except Exception as e:
        # print exception and write it to file

I'd appreciate any suggestions as to what could be going wrong here, or on how to diagnose or resolve it. Thanks.