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
```
fifo_queue = 'my-queue.fifo'
        queue_info = self.client.create_queue(QueueName=fifo_queue, Attributes={'FifoQueue': 'true'})
        queue_url = queue_info['QueueUrl']
        
        self.assertIn(fifo_queue, queue_url)
        
        self.client.delete_queue(QueueUrl=queue_url)
    def test_set_queue_policy(self):
        queue_name = 'queue-%s' % short_uid()
        queue_info = self.client.create_queue(QueueName=queue_name)
        queue_url = queue_info['QueueUrl']
        attributes = {
            'Policy': TEST_POLICY
        }
        self.client.set_queue_attributes(QueueUrl=queue_url, Attributes=attributes)
        attrs = self.client.get_queue_attributes(QueueUrl=queue_url, AttributeNames=['All'])['Attributes']
        self.assertIn('sqs:SendMessage', attrs['Policy'])
        attrs = self.client.get_queue_attributes(QueueUrl=queue_url, AttributeNames=['Policy'])['Attributes']
        self.assertIn('sqs:SendMessage', attrs['Policy'])
        
        self.client.delete_queue(QueueUrl=queue_url)
    def test_send_message_attributes(self):