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)
LAMBDA_EXECUTOR.cleanup(arn)
    try:
        arn_to_lambda.pop(arn)
    except KeyError:
        return not_found_error(func_arn(function))
    event_publisher.fire_event(event_publisher.EVENT_LAMBDA_DELETE_FUNC,
        payload={'n': event_publisher.get_hash(function)})
    i = 0
    while i < len(event_source_mappings):
        mapping = event_source_mappings[i]
        if mapping['FunctionArn'] == arn:
            del event_source_mappings[i]
            i -= 1
        i += 1
    result = {}
    return jsonify(result)
@app.route('%s/functions/<function>/code' % PATH_ROOT, methods=['PUT'])
def update_function_code(function):
    """ Update the code of an existing function
        ---
        operationId: 'updateFunctionCode'
        parameters:
            - name: 'request'
              in: body
    """
    data = json.loads(to_str(request.data))
    result = set_function_code(data, function)
    arn = func_arn(function)
    func_details = arn_to_lambda.get(arn)