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)
"""
    if 'S3Bucket' in function_code:
        s3_client = aws_stack.connect_to_service('s3')
        bytes_io = BytesIO()
        try:
            s3_client.download_fileobj(function_code['S3Bucket'], function_code['S3Key'], bytes_io)
            zip_file_content = bytes_io.getvalue()
        except Exception as e:
            raise ClientError('Unable to fetch Lambda archive from S3: %s' % e, 404)
    elif 'ZipFile' in function_code:
        zip_file_content = function_code['ZipFile']
        zip_file_content = base64.b64decode(zip_file_content)
    else:
        raise ClientError('No valid Lambda archive specified.')
    return zip_file_content
def get_java_handler(zip_file_content, handler, main_file):
    """Creates a Java handler from an uploaded ZIP or JAR.
    :type zip_file_content: bytes
    :param zip_file_content: ZIP file bytes.
    :type handler: str
    :param handler: The lambda handler path.
    :type main_file: str
    :param main_file: Filepath to the uploaded ZIP or JAR file.
    :returns: function or flask.Response
    """
    if is_zip_file(zip_file_content):
        def execute(event, context):
            result, log_output = lambda_executors.EXECUTOR_LOCAL.execute_java_lambda(
                event, context, handler=handler, main_file=main_file)
            return result