The lambda execution is not suspending and the lambda container has no port exposed when running a java 11 lambda with the latest localstack docker image by docker-compose with the environment variable LAMBDA_JAVA_OPTS=-agentlib:jdwp=transport=dt_socket,server=y,suspend=y,address=_debug_port_
    
It works fine for java8 runtime executions.

Docker command:

> localstack_1  | 2020-01-26T12:42:04:INFO:localstack.services.awslambda.lambda_executors: Running lambda cmd: CONTAINER_ID="$(docker create -i   -e ENV="$ENV" -e DOCKER_LAMBDA_USE_STDIN="$DOCKER_LAMBDA_USE_STDIN" -e HOSTNAME="$HOSTNAME" -e LOCALSTACK_HOSTNAME="$LOCALSTACK_HOSTNAME" -e AWS_LAMBDA_FUNCTION_TIMEOUT="$AWS_LAMBDA_FUNCTION_TIMEOUT" -e AWS_LAMBDA_FUNCTION_NAME="$AWS_LAMBDA_FUNCTION_NAME" -e AWS_LAMBDA_FUNCTION_VERSION="$AWS_LAMBDA_FUNCTION_VERSION" -e AWS_LAMBDA_FUNCTION_INVOKED_ARN="$AWS_LAMBDA_FUNCTION_INVOKED_ARN"  --rm "lambci/lambda:java11" "com.XXX.XXX.Handler")";docker cp "/tmp/localstack/zipfile.0c90736c/." "$CONTAINER_ID:/var/task"; docker start -ai "$CONTAINER_ID";

I think this is due to the fact that the classpath arguments and java opts are only being set if the rutime is equal to LAMBDA_RUNTIME_JAVA8 (line 211 of ocalstack/localstack/services/awslambda/lambda_executors.py , commit 03c6f4bf250edd18eb818ed65090f508636b0bff)
try:
                result, log_output = self._execute(func_arn, func_details, event, context, version)
            except Exception as e:
                if asynchronous:
                    if get_from_event(event, 'eventSource') == EVENT_SOURCE_SQS:
                        sqs_queue_arn = get_from_event(event, 'eventSourceARN')
                        if sqs_queue_arn:
                            
                            sqs_error_to_dead_letter_queue(sqs_queue_arn, event, e)
                    else:
                        
                        lambda_error_to_dead_letter_queue(func_details, event, e)
                raise e
            finally:
                self.function_invoke_times[func_arn] = invocation_time
            
            self._store_logs(func_details, log_output, invocation_time)
            
            return result, log_output
        
        if asynchronous:
            LOG.debug('Lambda executed in Event (asynchronous) mode, no response from this '
                      'function will be returned to caller')
            FuncThread(do_execute).start()
            return None, 'Lambda executed asynchronously.'
        return do_execute()
    def _execute(self, func_arn, func_details, event, context=None, version=None):
        """ This method must be overwritten by subclasses. """
        raise Exception('Not implemented.')
    def startup(self):