feat(docker): add support for rootless docker

[Friend-LGA]

As it seems that Rootless Docker is more secure alternative to the regular Docker it would be nice to be able to use Mailcow under the Rootless Docker.

I'm not the expert in the field, just was testing if it is possible to run Mailcow under the Rootless Docker at all.

These changes currently are not supposed to be merged, as it modifies basic docker-compose.yml for the purpose to be able to visually show the difference and, if everything's ok, then it can be transferred into new docker compose file or to some other logic.

I didn't do much, just removed unsupported lines and changed path to docker.sock. But it actually looks to be working just fine on my test server...

May be sysctls and ulimits options can be moved to some local docker config, for example under ~/.config?

Also I had to add CURRENT_USER_ID variable as for some reason docker compose wasn't able to use just $UID inside volumes section, I'm not sure why.

Linux Info:

uname -a

Linux hostname #66-Ubuntu SMP Fri Jan 20 14:29:49 UTC 2023 x86_64 x86_64 x86_64 GNU/Linux

Docker Info:

docker info

Client:
 Context:    rootless
 Debug Mode: false
 Plugins:
  compose: Docker Compose (Docker Inc.)
    Version:  v2.16.0
    Path:     /home/username/.docker/cli-plugins/docker-compose

Server:
 Containers: 20
  Running: 19
  Paused: 0
  Stopped: 1
 Images: 21
 Server Version: 23.0.0
 Storage Driver: overlay2
  Backing Filesystem: extfs
  Supports d_type: true
  Using metacopy: false
  Native Overlay Diff: false
  userxattr: true
 Logging Driver: json-file
 Cgroup Driver: systemd
 Cgroup Version: 2
 Plugins:
  Volume: local
  Network: bridge host ipvlan macvlan null overlay
  Log: awslogs fluentd gcplogs gelf journald json-file local logentries splunk syslog
 Swarm: inactive
 Runtimes: io.containerd.runc.v2 runc
 Default Runtime: runc
 Init Binary: docker-init
 containerd version: 31aa4358a36870b21a992d3ad2bef29e1d693bec
 runc version: v1.1.4-0-g5fd4c4d
 init version: de40ad0
 Security Options:
  seccomp
   Profile: builtin
  rootless
  cgroupns
 Kernel Version: 5.15.0-60-generic
 Operating System: Ubuntu 22.04.1 LTS
 OSType: linux
 Architecture: x86_64
 CPUs: 4
 Total Memory: 7.763GiB
 Name: hostname
 ID: 9b12ef02-ef97-4e74-9cea-0406aba841d0
 Docker Root Dir: /home/username/.local/share/docker
 Debug Mode: false
 Registry: https://index.docker.io/v1/
 Experimental: false
 Insecure Registries:
  127.0.0.0/8
 Live Restore Enabled: false
 Product License: Community Engine

WARNING: No cpu cfs quota support
WARNING: No cpu cfs period support
WARNING: No cpu shares support
WARNING: No cpuset support
WARNING: No io.weight support
WARNING: No io.weight (per device) support
WARNING: No io.max (rbps) support
WARNING: No io.max (wbps) support
WARNING: No io.max (riops) support
WARNING: No io.max (wiops) support
WARNING: bridge-nf-call-iptables is disabled
WARNING: bridge-nf-call-ip6tables is disabled

[milkmaker]

Thanks for contributing!

I noticed that you didn't select staging as your base branch. Please change the base branch to staging.
See the attached picture on how to change the base branch to staging:

[mkuron]

netfilter and ipv6nat won't work without root privileges. So no support for blocking IP addresses after multiple incorrect password attempts and no IPv6 support. These are things you will likely want to have on a mailserver, so I wouldn't recommend running rootlessly.

[Friend-LGA]

Can we use some external lib instead, for example fail2ban?

So it will be a combination:

• Rootless Mailcow (without netfilter and ipv6nat) + fail2ban

[mkuron]

It needs to watch the Docker log, so that probably won't work.

By the way, how do exposed network ports work in rootless docker? If they are done via a userland proxy, source IP addresses won't be preserved, which may turn your mailserver into an open relay and renders DNSBLs useless. You need iptables NAT rules to preserve source addresses.

[Dexus]

It needs to watch the Docker log, so that probably won't work.

it would work if docker is using journald or syslog etc. and fail2ban would work then. Have this setup currently build on my own, to get a better performant blocklist that I can share cross multiple servers.