sqs.changeMessageVisibility according to [this](https://docs.aws.amazon.com/AWSSimpleQueueService/latest/APIReference/API_ChangeMessageVisibility.html#API_ChangeMessageVisibility_Examples) makes a request directly to the Queue's URL rather than via the SQS Endpoint. (I'm already setting SQS endpoint to LOCALSTACK_HOSTNAME - makes no difference for this call)..

In localstack the queue URL host returned is by default set to the value of HOSTNAME_EXTERNAL, which I'm setting to localstack, but calling this method within a lambda, does not work and I get the error:

```
UnknownEndpoint: Inaccessible host: `localstack'. This service may not be available in the `us-east-1' region. 
```

So, how can I make the queue URL accessible from within a lambda using localstack? Effectively I need to make **http://localstack** accessible from within lambda.

I'm using the following cmd to start localstack:

```
LAMBDA_EXECUTOR=docker-reuse DEBUG=1 LAMBDA_REMOTE_DOCKER=0 DATA_DIR=/tmp/localstack/data HOSTNAME_EXTERNAL=localstack localstack start
```
kinesis.delete_stream(StreamName=self.TEST_STREAM_KINESIS_API_GW)
    def test_api_gateway_sqs_integration_with_event_source(self):
        
        aws_stack.create_sqs_queue(self.TEST_SQS_QUEUE)
        
        result = connect_api_gateway_to_sqs(
            'test_gateway4', stage_name=self.TEST_STAGE_NAME,
            queue_arn=self.TEST_SQS_QUEUE, path=self.API_PATH_DATA_INBOUND)
        
        self.create_lambda_function(self.TEST_LAMBDA_SQS_HANDLER_NAME)
        add_event_source(
            self.TEST_LAMBDA_SQS_HANDLER_NAME,
            aws_stack.sqs_queue_arn(self.TEST_SQS_QUEUE),
            True)
        
        test_data = {'spam': 'eggs & beans'}
        url = self.gateway_request_url(
            api_id=result['id'],
            stage_name=self.TEST_STAGE_NAME,
            path=self.API_PATH_DATA_INBOUND
        )
        result = requests.post(url, data=json.dumps(test_data))
        self.assertEqual(result.status_code, 200)
        parsed_json = xmltodict.parse(result.content)
        result = parsed_json['SendMessageResponse']['SendMessageResult']
        body_md5 = result['MD5OfMessageBody']
        attr_md5 = result['MD5OfMessageAttributes']
        self.assertEqual(body_md5, 'b639f52308afd65866c86f274c59033f')
        self.assertEqual(attr_md5, 'd41d8cd98f00b204e9800998ecf8427e')
    def test_api_gateway_sqs_integration(self):