I’m moving to a new machine soon and want to re-evaluate some security practices while I’m doing it. My current server is debian with all apps containerized in docker with root. I’d like to harden some stuff, especially vaultwarden but I’m concerned about transitioning to podman while using complex docker setups like nextcloud-aio. Do you have experience hardening your containers by switching? Is it worth it? How long is a piece of string?
Hey bigdickdonkey, I recently tried and wasn’t able to shit my way through podman, there just wasn’t enough chatter and guides about it. I plan to revisit it when Debian 13 comes out, which will include podman quadlets. I also tried to get podman quadlets to work on Ubuntu 24 and got closer, but still didn’t manage and Ubuntu is squicky.
I read about true user rootless Docker and decided that was too finicky to keep up to date. It needs some annoying stuff to update, from what I could tell. I was planning on many users having their own containers, and that would have gotten annoying to manage. Maybe a single user would be an OK burden.
The podman people make a good argument for running podman as root and using userns to divvy out UIDs to achieve rootless https://www.redhat.com/en/blog/rootless-podman-user-namespace-modes but since podman is on the back burner till there’s more community and Debian 13, I applied that idea to Docker.
So I went with root Docker with the goals of:
read only
set user to different UID:GID for each container
silo containers in individual Docker networks
nothing gets /var/run/docker.sock
cap_drop: all
security-opt=no-new-privileges
volumes all get tagged with :rw,noexec,nosuid,nodev,Z
This still has risk of the Docker daemon being hacked from the container itself somehow, which podman eliminates, but it’s as close to the podman ideal I can get within my knowledge now.
Most things will run as rootless+read-only+cap_drop with minor messing. Automatic ripping machine would not, but that project is a wild ride of required permissions. Everything else has succumbed, but I’ve needed to sometimes have a “pre launch container” to do permission changes or make somewhere like /opt writable.
I would transition one app stack at a time to the best security practices, and it’s easier since you don’t need to change container managers. Hope this helps!
Not sure if it makes a difference and not quite your question but I've just switched away from nextcloud-aio to just having my own docker compose, so I have better control and know what's going on more. I always found it funny and when installing on a new VPS decided to try. It was surprisingly straightforward and Ive been able to install everything I need.
Let me know if my docker compose would help. I still need to add the backup solution but it's going to be straightforward as well.
I'm running podman and podman-compose with no problem. And I'm happy. At first I was confused by the uid and gid mapping the containers have, but you'll get used to it.
This are some notes I took, please don't take all of it for the right choice.
I switched and was very glad to do so. You increase your security and so far I haven't seen any downside. Every container I've tried has worked without issues, even complex ones.
I also would like to switch to rootless, I have some experience with podman and, while I generally like it, it's not 100% compatible with (rootful) docker, and can have performance issues if you're not careful, especiallt with certain file systems like btrfs. I wonder if rootless docker is now better than podman, or preferred for some other reason.
Rootless Podman :) It requires you to learn a little bit of new syntax, for example, the way you mount volumes and pass environment variables can be slightly different, but there's nothing that hasn't worked for me.
I'm using this on uBlue uCore, which I would also strongly recommend for security reasons.
One of the main reason I switched to podman was its compatibility with firewalld. Haven't used rootless docker, but podman and podman-compose gets the job done for me.