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)
) % (docker_cmd, rm_flag, container_name, mount_volume_str, env_vars_str, network_str, docker_image)
                LOG.debug(cmd)
                run(cmd)
                if not mount_volume:
                    LOG.debug('Copying files to container "%s" from "%s".' % (container_name, lambda_cwd))
                    cmd = (
                        '%s cp'
                        ' "%s/." "%s:/var/task"'
                    ) % (docker_cmd, lambda_cwd, container_name)
                    LOG.debug(cmd)
                    run(cmd)
                LOG.debug('Starting container: %s' % container_name)
                cmd = '%s start %s' % (docker_cmd, container_name)
                LOG.debug(cmd)
                run(cmd)
                
                time.sleep(1)
            
            LOG.debug('Getting the entrypoint for image: %s' % (docker_image))
            cmd = (
                '%s image inspect'
                ' --format="{{ .ContainerConfig.Entrypoint }}"'
                ' %s'
            ) % (docker_cmd, docker_image)
            LOG.debug(cmd)
            run_result = run(cmd)
            entry_point = run_result.strip('[]\n\r ')
            container_network = self.get_docker_container_network(func_arn)
            LOG.debug('Using entrypoint "%s" for container "%s" on network "%s".'
                % (entry_point, container_name, container_network))