issue with volumes

[cfoellmann]

Hi @tiredofit

I am in the process of creating a domain-joined printserver. Resulting in running these services:

• cupsd
• smbd (samba)
• avahi
• nmbd (samba)

my issue is now that I want/need to persist a lot of stuff and we do hostmounting in our environment. But when I do this in the docker-compose.yml

    volumes:
      - /var/lib/docker/compose/cups101/config/cups:/etc/cups
      - /var/lib/docker/compose/cups101/config/samba:/etc/samba
      #      - /var/lib/docker/compose/cups101/spool:/var/spool/cups
      - /var/lib/docker/compose/cups101/log/cups:/var/log/cups
      - /var/lib/docker/compose/cups101/log/samba:/var/log/samba

the container will not "use" the mapped/mounted folders. How can I allow for my image to use mapped folders in my container?

[tiredofit]

All looks really good with the bind mounts in your volumes - Unless the applications null out the contents of the folder your outside (var/lib) should be mapping into your paths in the container without issue. Does this only happen with this image?

[cfoellmann]

when I read my issue now it is really misleading in describing the issue.

The mounted folders generally work. BUT: the mounts are connected but empty. That results in empty folders like "/etc/cups" within the container. That means the services have no config files to run.

Normally I was expecting the contents of the containers to "transfer" over to the mount. but that does not happen.

Mounts/Volumes do work for us. But I have not mounted folders into your images so far. only single files

[tiredofit]

You'll during build time want to create seed folders to move the stuff out of the way if going to expose a bind mount that way - The hosts contents will always override the containers thus creating the blank files.

Alternatively I believe you can take advantage of the VOLUME command within the Dockerfile which should allow for better persistence. I see issues with it and actively avoid it and prefer the seed approach.

Random snippets:

dockerfile..

mkdir -p /assets/<image_name>/etc
cp -aR /etc/cups /assets/<image_name>/etc

init..

if dir_empty /etc/cron ; then 
  mkdir -p /etc/cron
  cp -aR /assets/<image_name>/etc/cron /etc
  chown -R user:group /etc/cron
fi

dirty, but thats generally how i've been building images..