Docker service can't run in background

General
1

I have build my own image and push it to my registry in the swarm, to create an service on base of the image.

#dockerfile    
   FROM ubuntu:latest

    RUN apt update -qq && apt install -qqy samba

    RUN useradd -ms /bin/bash -p "$1$Ka9zKZwA$G70Ozk7eUjIzUZcuTAu44." docker
    RUN (echo "sysadmin"; sleep 5; echo "passwd" ) | smbpasswd -s -a docker

    RUN mkdir /mnt/share

    RUN echo [docker] >> /etc/samba/smb.conf
    RUN echo comment = share for docker >> /etc/samba/smb.conf
    RUN echo path = /mnt/tidepod/ >> /etc/samba/smb.conf
    RUN echo browseable = yes >> /etc/samba/smb.conf
    RUN echo valid user = docker >> /etc/samba/smb.conf
    RUN echo writeable = yes >> /etc/samba/smb.conf
    RUN echo create mask = 0777 >> /etc/samba/smb.conf
    RUN echo directory mask = 0777 >> /etc/samba/smb.conf

    EXPOSE 139/tcp
    EXPOSE 445/tcp
    CMD service smbd start  && tail -f /dev/null

If I try to run the image as singel container it works and the share is accesable.

But when I try to create the service with an stackfile the service starts and shutdown imidently.

#stackfile
version: "3.6"
services:
  swarm-share:
    image: registry.de:5000/swarm-share
    deploy:
      replicas: 1
      placement:
        constraints:
          - node.role == manager
    volumes:
      - /mnt/share:/mnt/share
    ports:
      - "139:139"
      - "445:445"

How can I create the service?