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
```
@app.route('%s/functions/<function>/configuration' % PATH_ROOT, methods=['PUT'])
def update_function_configuration(function):
    """ Update the configuration of an existing function
        ---
        operationId: 'updateFunctionConfiguration'
        parameters:
            - name: 'request'
              in: body
    """
    data = json.loads(to_str(request.data))
    arn = func_arn(function)
    
    LAMBDA_EXECUTOR.cleanup(arn)
    lambda_details = arn_to_lambda.get(arn)
    if not lambda_details:
        return error_response('Unable to find Lambda function ARN "%s"' % arn,
            404, error_type='ResourceNotFoundException')
    if data.get('Handler'):
        lambda_details.handler = data['Handler']
    if data.get('Runtime'):
        lambda_details.runtime = data['Runtime']
    lambda_details.set_dead_letter_config(data)
    env_vars = data.get('Environment', {}).get('Variables')
    if env_vars is not None:
        lambda_details.envvars = env_vars
    if data.get('Timeout'):
        lambda_details.timeout = data['Timeout']
    return jsonify(data)
@app.route('%s/functions/<function>/policy' % PATH_ROOT, methods=['POST'])
def add_permission(function):