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)
response_obj = jsonify(response_obj)
            details['Headers']['Content-Type'] = 'application/json'
        else:
            response_obj = str(response_obj)
            details['Headers']['Content-Type'] = 'text/plain'
        return response_obj, details['StatusCode'], details['Headers']
    
    not_found = None
    if arn not in arn_to_lambda:
        not_found = not_found_error(arn)
    elif qualifier and not arn_to_lambda.get(arn).qualifier_exists(qualifier):
        not_found = not_found_error('{0}:{1}'.format(arn, qualifier))
    if not_found:
        forward_result = forward_to_fallback_url(func_arn, data)
        if forward_result is not None:
            return _create_response(forward_result)
        return not_found
    if invocation_type == 'RequestResponse':
        result = run_lambda(asynchronous=False, func_arn=arn, event=data, context={}, version=qualifier)
        return _create_response(result)
    elif invocation_type == 'Event':
        run_lambda(asynchronous=True, func_arn=arn, event=data, context={}, version=qualifier)
        return _create_response('', status_code=202)
    elif invocation_type == 'DryRun':
        
        return _create_response('', status_code=204)
    return error_response('Invocation type not one of: RequestResponse, Event or DryRun',
                          code=400, error_type='InvalidParameterValueException')
@app.route('%s/event-source-mappings/' % PATH_ROOT, methods=['GET'])
def list_event_source_mappings():