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)
'isBase64Encoded': False,
            'resource': resource_path,
            'httpMethod': method,
            'queryStringParameters': query_string_params,
            'requestContext': request_context,
            'stageVariables': {}  
        }
        return run_lambda(event=event, context={}, func_arn=func_arn)
    except Exception as e:
        LOG.warning('Unable to run Lambda function on API Gateway message: %s %s' % (e, traceback.format_exc()))
def process_sns_notification(func_arn, topic_arn, subscriptionArn, message, message_attributes, subject='',):
    try:
        event = {
            'Records': [{
                'EventSource': 'localstack:sns',
                'EventVersion': '1.0',
                'EventSubscriptionArn': subscriptionArn,
                'Sns': {
                    'Type': 'Notification',
                    'TopicArn': topic_arn,
                    'Subject': subject,
                    'Message': message,
                    'Timestamp': timestamp(format=TIMESTAMP_FORMAT_MILLIS),
                    'MessageAttributes': message_attributes
                }
            }]
        }
        return run_lambda(event=event, context={}, func_arn=func_arn, asynchronous=True)
    except Exception as e:
        LOG.warning('Unable to run Lambda function on SNS message: %s %s' % (e, traceback.format_exc()))