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
```
"""Simple class to mimick the behavior of variable '$input' in AWS API Gateway integration velocity templates.
    See: http://docs.aws.amazon.com/apigateway/latest/developerguide/api-gateway-mapping-template-reference.html"""
    def __init__(self, value):
        self.value = value
    def path(self, path):
        from jsonpath_rw import parse
        value = self.value if isinstance(self.value, dict) else json.loads(self.value)
        jsonpath_expr = parse(path)
        result = [match.value for match in jsonpath_expr.find(value)]
        result = result[0] if len(result) == 1 else result
        return result
    def json(self, path):
        return json.dumps(self.path(path))
    def __repr__(self):
        return '$input'
class VelocityUtil:
    """Simple class to mimick the behavior of variable '$util' in AWS API Gateway integration velocity templates.
    See: http://docs.aws.amazon.com/apigateway/latest/developerguide/api-gateway-mapping-template-reference.html"""
    def base64Encode(self, s):
        if not isinstance(s, str):
            s = json.dumps(s)
        encoded_str = s.encode(config.DEFAULT_ENCODING)
        encoded_b64_str = base64.b64encode(encoded_str)
        return encoded_b64_str.decode(config.DEFAULT_ENCODING)
    def base64Decode(self, s):
        if not isinstance(s, str):
            s = json.dumps(s)
        return base64.b64decode(s)
    def toJson(self, obj):