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
```
def __init__(self, msg, code=400):
        super(ClientError, self).__init__(msg)
        self.code = code
        self.msg = msg
    def get_response(self):
        if isinstance(self.msg, Response):
            return self.msg
        return error_response(self.msg, self.code)
class LambdaContext(object):
    def __init__(self, func_details, qualifier=None):
        self.function_name = func_details.name()
        self.function_version = func_details.get_qualifier_version(qualifier)
        self.invoked_function_arn = func_details.arn()
        if qualifier:
            self.invoked_function_arn += ':' + qualifier
    def get_remaining_time_in_millis(self):
        
        return 1000 * 60
def cleanup():
    global event_source_mappings, arn_to_lambda
    arn_to_lambda = {}
    event_source_mappings = []
    LAMBDA_EXECUTOR.cleanup()
def func_arn(function_name):
    return aws_stack.lambda_function_arn(function_name)
def add_function_mapping(lambda_name, lambda_handler, lambda_cwd=None):
    arn = func_arn(lambda_name)
    arn_to_lambda[arn].versions.get('$LATEST')['Function'] = lambda_handler
    arn_to_lambda[arn].cwd = lambda_cwd
def add_event_source(function_name, source_arn, enabled, batch_size=None):