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
```
queue_name = 'queue-%s' % short_uid()
        queue_url = self.client.create_queue(QueueName=queue_name)['QueueUrl']
        payload = {}
        attrs = {'attr1': {'StringValue': 'val1', 'DataType': 'String'}}
        self.client.send_message(QueueUrl=queue_url, MessageBody=json.dumps(payload),
                                 MessageAttributes=attrs)
        result = self.client.receive_message(QueueUrl=queue_url, MessageAttributeNames=['All'])
        messages = result['Messages']
        self.assertEquals(messages[0]['MessageAttributes'], attrs)
        
        self.client.delete_queue(QueueUrl=queue_url)
    def test_send_message_with_invalid_string_attributes(self):
        queue_name = 'queue-%s' % short_uid()
        queue_url = self.client.create_queue(QueueName=queue_name)['QueueUrl']
        payload = {}
        
        
        attrs = {'attr1':
        {'StringValue': 'invalid characters, %s, %s, %s' % (chr(8), chr(11), chr(12)), 'DataType': 'String'}}
        with self.assertRaises(Exception):
            self.client.send_message(QueueUrl=queue_url, MessageBody=json.dumps(payload),
                                     MessageAttributes=attrs)
        
        self.client.delete_queue(QueueUrl=queue_url)
    def test_dead_letter_queue_config(self):