NiFi & Registry in docker with (not working) persistence

docker-compose.yml

version: "3"
services:
  nifi:
    hostname: demo.nifi
    image: apache/nifi:1.11.4
    container_name: nifi
    ports:
      - 8080:8080
      - 443:8443
    links:
      - registry
    volumes:
      - ./for_nifi/tmp/nifi:/opt/nifi_in
      #- ./for_nifi/nifi-persisted/:/opt/nifi/
      - ./for_registry/demo.nifi:/opt/demo.nifi:ro
  registry:
    hostname: registry
    image: apache/nifi-registry:0.6.0
    container_name: registry
    volumes:
      - ./for_registry/registry/:/opt/registry:ro
      - ./extensions:/opt/nifi/nifi-current/extensions
    ports:
      - 18080:18080

1. persistence is not working i.e. when stopping the docker container all the flows or configuration to the linked registry is gone
2. I would want to configure the registry with git-based persistence and store this config setting somewhere such that when restarting the container the git based provider is used