Mount Arduino Serial, Use Host network in Docker Swarm

test.yml

version: '3'

networks:
  docker_host:
    external:
      name: 'host'

services:
  docker-parent:
    image: docker:latest
    command:
      - "/bin/sh"
      - -c
      - |
          trap "docker rm -f docker-child" SIGTERM
          echo "Init work ..."
          docker rm -f docker-child
          docker rmi alpine:latest
          if [[ -z $$SERIAL_PORT ]]; then \
            docker run  --name=docker-child \
                        --net=host \
                        alpine:latest \
                        ping -c3 $$HOSTNAME && tail -f /dev/null &
          else
            docker run  --name=docker-child \
                        --net=host \
                        --device=$$SERIAL_PORT \
                        alpine:latest \
                        sh -c "ping -c3 $$HOSTNAME > $$SERIAL_PORT && tail -f /dev/null" &
          fi
          CHILD=$$!
          echo "Wait for $$CHILD ..."
          wait $$CHILD
          echo "Exit ..."
    environment:
      SERIAL_PORT: /dev/ttyACM0
      HOSTNAME: RPi0
    volumes:
      - "/var/run/docker.sock:/var/run/docker.sock:ro"
    networks:
      - 'docker_host'
    deploy:
      replicas: 1
      restart_policy:
        condition: any
        delay: 30s
      placement:
        constraints:
          - node.hostname == RPi0