Docker rootless

We have made it possible to run docker containers rootless now. Ie. as a normal user, without root access (for in depth info see: https://docs.docker.com/engine/security/rootless).

You need to prepare your system. Follow the instructions given by:

 $ dockerd-rootless-setuptool.sh

By default this will store docker images in ~/.local/share/docker. Unfortunately this does not work correctly with a network mounted homedisk. There are 2 ways of resolving this, use only one of them, because they conflict with each other.

Solution 1

To solve this you need to find a suitable location on your local disk to store files. Usually /mnt/D/<subdir> or /var/tmp/<subdir> are good choices. You set this by editing the data-root in ~/.config/docker/daemon.json. That file and directory may not (yet) exist. Example:

 $ [ -d ~/.config/docker ] || mkdir -p ~/.config/docker
 $ edit ~/.config/docker/daemon.json to contain:
 {
   "data-root": "/mnt/D/<subdir>"
 }
 $ systemctl --user restart docker

Solution 2

An alternative approach (make sure to remove ~/.config/docker/daemon.json when you do this!) is to store a small ext4 formatted diskimage in your homedir and make it mountable:

 $ truncate -s 25G ~/.docker.img
 $ nfs4_setfacl -a 'A::nobody@rug.nl:X' ~
 $ nfs4_setfacl -a 'A::nobody@rug.nl:RWX' ~/.docker.img 
 $ mkfs.ext4 -E root_owner -m0 -L docker ~/.docker.img
 $ chmod 755 ~/.local/share
 $ nfs4_setfacl -a 'A::nobody@rug.nl:X' ~/.local ~/local/share

Now you need to make sure this disk image is mounted when you login. For that you need to edit ~/.pam_mount.conf.xml to contain:

 <?xml version="1.0" encoding="utf-8" ?>
 <!DOCTYPE pam_mount SYSTEM "pam_mount.conf.xml.dtd">
 <pam_mount>
   <volume fstype="ext4" mountpoint="~/.local/share/docker" options="async,nosuid,loop,exec,noatime,nodev" path="~/.docker.img" />
 </pam_mount>

Then logout and login again (or do ssh 127.0.0.1 exit)

testing docker

$ docker run hello-world
$ docker run -it ubuntu bash
$ docker run -d -p 8881:8080 inanimate/echo-server

Then check in your browser localhost:8881

Standard docker installation

It is still possible to request a standard docker installation (ie. the docker daemon runs as root) for your personal LWP (ie. not for any shared system such as systems in the computer labs or https://vlwp.rug.nl).

Personal use:

- just send a message to mailto:lwp@rug.nl stating your intentions
- by default you will be able to run any container but will not be able to mount a local path into the container.
- these limitations can be lifted on a case by case basis (ie. we have to know about it)