def update_token(self):
    '''update_token uses HTTP basic authentication to get a token for
    Docker registry API V2 operations. We get here if a 401 is
    returned for a request.

    Parameters
    ==========
    response: the http request response to parse for the challenge.
    
    https://docs.docker.com/registry/spec/auth/token/
    '''
    # Add Amazon headers

    tokens = self.aws.get_authorization_token()
    token = tokens['authorizationData'][0]['authorizationToken']    

    try:
        token = {"Authorization": "Basic %s" % token}
        self.headers.update(token)

    except Exception:
        bot.error("Error getting token.")
        sys.exit(1)
update_token uses HTTP basic authentication to get a token for
    Docker registry API V2 operations. We get here if a 401 is
    returned for a request.

    Parameters
    ==========
    response: the http request response to parse for the challenge.
    
    https://docs.docker.com/registry/spec/auth/token/