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)
return ContainerInfo(container_name, entry_point)
    def destroy_docker_container(self, func_arn):
        """
        Stops and/or removes a docker container for a specific lambda function ARN.
        :param func_arn: The ARN of the lambda function.
        :return: None
        """
        with self.docker_container_lock:
            status = self.get_docker_container_status(func_arn)
            docker_cmd = self._docker_cmd()
            
            container_name = self.get_container_name(func_arn)
            if status == 1:
                LOG.debug('Stopping container: %s' % container_name)
                cmd = (
                    '%s stop -t0 %s'
                ) % (docker_cmd, container_name)
                LOG.debug(cmd)
                run(cmd, asynchronous=False, stderr=subprocess.PIPE, outfile=subprocess.PIPE)
                status = self.get_docker_container_status(func_arn)
            if status == -1:
                LOG.debug('Removing container: %s' % container_name)
                cmd = (
                    '%s rm %s'
                ) % (docker_cmd, container_name)
                LOG.debug(cmd)
                run(cmd, asynchronous=False, stderr=subprocess.PIPE, outfile=subprocess.PIPE)
    def get_all_container_names(self):
        """
        Returns a list of container names for lambda containers.