Good Morning from my Robotics Lab! This is Shadow_8472 and today I am exploring fuse-overlayfs as a possible patch between Podman and NFS. Last week’s post was practically a freebee, but I expect this one to be a doozy if it’s even possible. Let’s get started!
Context
For my homelab, I want to run Nextcloud in a rootless Podman 3.0.1 container with storage volumes on our NFS. For logistical reasons, Nextcloud needs to be on RedLaptop running Debian 11 (Linux kernel 5.10.0-26-amd64 x86_64). The NFS share I wish to share is mounted via systemd.
My most promising lead is from Podman Github maintainer rhatdan on October 28, 2023, where he made a comment about “fuse file system,” asking his colleague, @giuseppe, for thoughts to which there has been no reply as of the afternoon of November 10 [1]. I documented a number of major milestones there, which I’ll be covering here.
File System Overlays
Fuse file system turned out to be fuse-overlayfs, one of a few systems for fusing file systems. Basically: there are times when it’s useful to view two or more file systems at once. File system overlays can designate a lower file system and an upper file system. Any changes (file creation, deletion, movement, etc.) in this combined file system manifest in the upper file system, leaving the lower file system[s] alone.
Through a lot of trial and error, I set up a lower directory, an upper directory, a work directory, and a mountpoint. My upper directory and work directory had to be on the NFS, but I ran into an error about setting times. I double checked that there were no major problems related to Daylight Savings Time ending, but wasn’t able to clear the error. I sent out some extra help requests, but got no replies (Sunday, Nov. 12). A third of my search results are in Chinese, and the others are either not applicable or locked behind a paywall. Unless something changes, I’m stuck.
Quadlets
Github user eriksjolund got back to me with another idea: quadlets [1]. Using this project merged into Podman 4.4 and above, he demonstrated a Nextcloud/MariaDB/Redis/Nginx setup that saves all files as the underprivileged user running the containers. In theory, this sidesteps the NFS incompatibilities I’ve been experiencing all together.
The first drawback from my perspective is that I need to re-define all my containers as systemd services, which is something I’ve admittedly been meaning to do anyway. A second is again that this is a feature merged into Podman much later than what I’m working with. Unless I care to go digging through the Podman GitHub myself, I’m stuck with old code people will be reluctant to support.
Distro Hunt
Why am I even using Debian still? What is its core purpose? Stability. Debian’s philosophy is to provide proven software with few or no surprises left and the user polishes it to taste. As my own sysadmin, I can afford a little downtime. I don’t need the stability of a distro supporting the most diverse Linux family tree. Besides, this isn’t the first time community support has suggested features in the future of my installation’s code base. Promising solutions end in broken links. RAM is becoming a concern. Apt package manager has proven more needy than I’d care to babysit. If I am to be honest with myself, it’s time to start sunsetting Debian on this system and find something more up-to-date for RedLaptop. I’ll keep it around for now just in case.
My first choice was Fedora to get to know the RedHat family better. Fedora 39 CoreOS looked perfect for its focus on containers, but it looks like it will require a week or two to configure and might not agree with installing non-containerized software. Fedora 39 Server was more feature complete, but didn’t load up for my BIOS (as opposed to the new standard of UEFI); I later learned that new BIOS-based installations were dropped on or around Fedora 37.
I carefully considered other distributions with the aid of pkgs.org. Debian/Ubuntu family repositories go up to 4.3. Alpine Linux lacks systemd. Souls Linux is for desktops. OpenSuse Tumbleweed comes with warnings about being prepared to compile kernel modules. Arch is… Arch.
Fresh Linux Installation
With time running out in the week, I decided to forgo sampling new distros and went with minimal Rocky 9. Installation went as best can be expected. I added/configured cockpit, podman, cockpit-podman, nfs-utils, and nano. I added a podmanuser account, set it up to allow-lingering, and downloaded the container images I plan on working with on this machine: PiHole, Unbound; Caddy; Nextcloud, Redis, MariaDB; busybox.
Takeaway
I write this section on Friday afternoon, and I doubt I have enough time remaining to properly learn Quadlets and rebuild my stack, so I’m going to cut it off here. From what I’ve gathered already, Quadlets mostly uses Systemd unit files, a format I’ve apparently worked with before, but also needs Kubernetes syntax to define pods. I don’t know a thing about using Kubernetes. If nothing else, perhaps this endeavor will prepare me for a larger project where larger scale container orchestration is needed.
Final Question
Do you know of a way I might have interfaced Podman 3 with NFS? Did I look in the wrong places for help (Debian forums, perhaps)?
I look forward to hearing from you on my Socials!
Work Cited
[1]. Shadow_8472, D. “rhdan” Walsh, E. Sjölund, “Rootless NFS Volume Permissions: What am I doing wrong with my Nextcloud/MaraiDB/Redis pod? #20519,” github.com, Oct. 27, 2023-Nov. 10, 2023. [Online]. Available: https://github.com/containers/podman/discussions/20519#discussioncomment-7410665. [Accessed Nov. 12, 2023].
