The update_function_configuration currently returns an empty dict no matter what but certain lambda libraries (ie, Zappa) require a realistic return value... which is simply the current config after being updated.

https://github.com/localstack/localstack/blob/9cba1010dfcbf2b7672df4d7da46b7e8ab287f64/localstack/services/awslambda/lambda_api.py#L872

https://boto3.amazonaws.com/v1/documentation/api/latest/reference/services/lambda.html#Lambda.Client.update_function_configuration

There might also be some other magic enriching that result but my quick read-through looks like it's an empty dict.



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if not msg:
        msg = 'The resource you requested does not exist.'
        if ref:
            msg = '%s not found: %s' % ('Function' if ':function:' in ref else 'Resource', ref)
    return error_response(msg, 404, error_type='ResourceNotFoundException')
@app.before_request
def before_request():
    
    transfer_encoding = request.headers.get('Transfer-Encoding', '').lower()
    if transfer_encoding == 'chunked':
        request.environ['wsgi.input_terminated'] = True
@app.route('%s/functions' % PATH_ROOT, methods=['POST'])
def create_function():
    """ Create new function
        ---
        operationId: 'createFunction'
        parameters:
            - name: 'request'
              in: body
    """
    arn = 'n/a'
    try:
        data = json.loads(to_str(request.data))
        lambda_name = data['FunctionName']
        event_publisher.fire_event(event_publisher.EVENT_LAMBDA_CREATE_FUNC,