Nothing fancy, just VNET jails based on ZFS templates (vanilla FreeBSD rootfs) and epair interfaces (which I truck to various VLANs on the host's egress interface).
One pattern that I've found useful is to give each jail a persistently delegated ZFS dataset called "data." This lets me reprovision the OS image for the jail without having to backup and restore its application data (such as a Postgres DB). It also allows each jail to manage its own ZFS snapshots.
The only thing that was a bit hairy was generating unique interface names and MAC addresses for each jail's VNET interface. My first instinct was to derive the interface name from the jail name, but interface names on FreeBSD are limited to 15 characters, and occasionally I'd hit this limit.
In the end I did some dark magic using md5 sums of the jail name / host interface MAC address. Kind of ugly but I really didn't want to introduce any dependencies besides /bin/sh.
[0] https://github.com/cullumsmith/infrastructure/blob/master/fi...
That was in 2007 so the control plane (scheduler and automation) were built from scratch and we had very few reference points for the overall design. If I was building that today I’d probably still use ZFS clones but at filesystem level instead of block devices, and serve jails over NFS if I can get away with it, the iSCSI part was always a little janky.
https://github.com/fsmv/daemon/
It's a bad time for me to be mentioning it because I have a major update that's not quite ready to release that changes some client APIs and makes the whole thing much nicer with fully automatic lets encrypt. I haven't had the space to work on it for a while unfortunately.
Author of the article seem to know what they are doing so I'm puzzled why they don't use `bsdinstall jail /path/to/jail` to implement basejail instead of manually unpacking archives.
No need for separate custom rc script to start `lo1`, it can be done with `cloned_interfaces` directive in rc.conf.
Updating and upgrading jails by passing `-b /path/to/jail` to `freebsd-update` works, but new recommended way has lately been `-j <jailname>`.
Cool article overall, the beauty of FreeBSD is also in possibility to do things in many different ways.
FreeBSD's native support for ZFS snapshots and jails
provides a powerful foundation for immutable deployments.
[1]: https://github.com/opencontainers/runtime-spec/pull/1286 [2]: https://github.com/samuelkarp/runj
Also found this self host on a Raspberry Pi helpful.[1]
[0] https://bastillebsd.org/getting-started/
[1] https://www.sharpwriting.net/project/bastille-jail-managemen...
ZFS has been stable in FreeBSD for something like 17 years, and FreeBSD jails have been around for something like 25 years.
By the time Docker hit 1.0 (about 11 years ago), the use of snapshots and jails had already been normal parts of life in the FreeBSD space for over half of a decade.
But at the same time, the reason Docker won was not because it was groundbreaking tech or because it was amazingly well tested or anything. Just as one example, it has a years old bug which actively gets more comments every week having to do with Docker grossly mishandling quotes in env files.
No, the reason it won is because the development experience and the deploy experience is easy, especially when you are on Linux AND on macOS. I can’t run FreeBSD jails or ZFS on macOS, can I? Definitely not with one file and one command.
Jails and ZFS are amazing tech but they are not accessible. Docker made simple things very simple while being cross-platform enough. Do I feel gross using it? Yeah. It’s a kludgy solution to the problem. But it gets the job done and is supported by every provider out there. I am excited that it is being ported to FreeBSD though I know it will be a very long process.
On macOS, docker actually launches a Linux VM to run containers. If this counts, then yes, you can run FreeBSD jails or zfs on macOS, by running a FreeBSD VM.
I dislike the implementation but I cannot deny that the UX is good enough to be very popular.
You’ll be sacrificing a lot and have to hand-roll a lot if you want your organization to switch from Linux+docker to FreeBSD+jails
I imagine FreeBSD could do something similar if they aren't already. IIRC FreeBSD has a Linux emulation layer (but I don't know how much attention it still gets), and it's had containerization primitives longer than linux, so some amount of filling in the gaps in containerization features and syscall tables (if needed) could possibly yield an OCI compatibility later (for all I know all this already exists).
The problem, and the reason if this doesn't exist why people probably weren't as interested in doing the work, is it would always be "mostly" compatible and working and there would be no guarantee that the underlying software wouldn't exhibit bugs or weird behavior from small behavior differences in the platform when emulating something else. Why open yourself up to the headache when you can just run Linux with containers or build what you want on FreeBSD with jails and their own native containerization primitives.
You would need to do more work yourself to fetch and run jails probably, and I don't know if there's a hosted repository of 'jail images', but in return, you'd probably have a nicer system (at least, I'd like such a system more than running containers on google container optimized linux)
But that has nothing to do with their respective UXs. It's a Linux vs FreeBSD signal.
No it wasn’t. Docker was late to the party even for Linux (and Linux was late compared to every other “UNIX”).
OpenVZ was around for years before docker. Its main issue was that it required out-of-tree kernel code. But there were some distributions that did still ship OpenVZ support. In fact it’s what Proxmox originally used. And it worked very well.
Then LXC came along. Fun fact, Docker was originally used LXC itself. But obviously that was a long time ago too.
I’ve used both OpenVZ and LXC in production systems before Docker came along. But I’ve always preferred FreeBSD Jails + ZFS to anything Linux has offered.
Docker's killer selling point was that it solved a very common and specific developer problem, not that it provided operational improvements over the state of the art on Linux. From an operational perspective, Docker has generally been a downgrade compared to LXC. (I say this as a maintainer of runc, the container runtime that underpins Docker, and as someone who worked a lot on Docker back in the early days and somewhat less today.)
Who couldn’t become famous with something like a $200M budget?
Feel like they spent it on marketing instead.
Podman is arguably technically superior yet people stay with Docker out of habit…
There is work ongoing to try to make this more native on FreeBSD (by using Linux jails) but that work is not complete yet.
So, if you want to get the same kind of experience as Docker on FreeBSD, you are forced to use jails.
The only reason Docker seems accessible is because it's native to the platform people seem to like for running all their services, but if you're dealing with FreeBSD, you most certainly would not just "use Docker" to deploy your stuff. Because you would get worse performance than if you had just used Linux.
So the answer to "Isn't this just Docker with extra steps?" is truly and absolutely "No". Not because of some kind of old man shouting at cloud argument, but because if you are on FreeBSD (for whatever reason that might be) you can't just use Docker as an easier replacement for Jails (at least right now).
You've got a good take on things, and I do not disagree with what you've written.
Same thing could be done in FreeBSD. Someone needs to put in the work…
I also find myself using nspawn just to isolate apps like firefox, etc.