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
```
return obj and json.dumps(obj)
def render_velocity_template(template, context, variables={}, as_json=False):
    import airspeed
    
    template = re.sub(r'(^|\n)#\s+set(.*)', r'\1#set\2', template, re.MULTILINE)
    t = airspeed.Template(template)
    var_map = {
        'input': VelocityInput(context),
        'util': VelocityUtil()
    }
    var_map.update(variables or {})
    replaced = t.merge(var_map)
    if as_json:
        replaced = json.loads(replaced)
    return replaced
def check_valid_region(headers):
    """ Check whether a valid region is provided, and if not then raise an Exception. """
    auth_header = headers.get('Authorization')
    if not auth_header:
        raise Exception('Unable to find "Authorization" header in request')
    replaced = re.sub(r'.*Credential=([^,]+),.*', r'\1', auth_header)
    if auth_header == replaced:
        raise Exception('Unable to find "Credential" section in "Authorization" header')
    
    
    parts = replaced.split('/')
    region = parts[2]
    if region not in config.VALID_REGIONS:
        raise Exception('Invalid region specified in "Authorization" header: "%s"' % region)
def set_default_region_in_headers(headers):