etc VS zfsbootmenu

Since this is now a share your prompt thread, here's mine:

https://github.com/rollcat/etc/tree/master/cmd/prompter

It's quite portable (didn't test on Windows though); ~170 lines of Go; no dependencies outside of stdlib; calls no external commands; supports SSH, git, Docker, nix, and virtualenv; extremely simple to hack on.

It's fairly easy to grab info from .git for your own purposes. For example, the program that generates my PS1 peeks there (without wasting precious cycles on shelling out to the git command) to find the current branch we're on:

https://github.com/rollcat/etc/blob/b2fd739/cmd/prompter/mai...

Depends on what you're trying to do. If you're shelling out to git(1) or docker(1), rather than e.g. recursively checking for the presence of .git in parent directories, or inspecting ~/.docker/config.json, then the fork+exec overhead is already quite significant. Next if you're parsing ~/.docker/config.json in shell, you're most likely either asking for trouble or (again) shelling out to jq. Writing it all in an interpreted language means you're paying the cost of interpreter startup, which on underpowered systems can take hundreds of milliseconds even when idle. OTOH loading a static binary to memory happens only once, and with Go you can trivially cross-compile.

I also have a fallback shell one-liner, without any of the fanciness like displaying the current git branch:

https://github.com/rollcat/etc/tree/master/cmd/prompter#i-li...

We use a couple nice home-grown functions in ZFSBootMenu to help debug things. We have a zdebug logging function that's peppered liberally throughout the code base - https://github.com/zbm-dev/zfsbootmenu/blob/master/zfsbootme...

Hitting ctrl-t on our main menu will, when booting with debug logging enabled, show a screen like this: https://imgur.com/Ge75zkP

We also have a flamegraph profiling mechanism that can be enabled with https://github.com/zbm-dev/zfsbootmenu/blob/master/zfsbootme... . That will dump data to a serial port, which when re-assembled, can be used to produce a graph like https://raw.githubusercontent.com/zbm-dev/zfsbootmenu/master...

Bash is suprisingly flexible.

A lot of what's in the Pure Bash Bible is horrifically slow. Many of those things are substantially faster, even when paying the cost of starting a new process, when you use an external and commonly available tool. I wrote a bash performance profiler that outputs data in a format that flamegraph.pl recognizes - it really helped identify where we could improve the performance of ZFSBootMenu.

https://github.com/zbm-dev/zfsbootmenu/releases/tag/v1.12.0

Don't fall in the trap of thinking things have to be written entirely in bash; it's okay to use other tools to help fill in the gaps.

If instead of "opensuse" you're asking for bootloader as grub can't boot from zfs, then, like i metnioned, i don't use grub2, i uninstalled it, instead i'm using https://github.com/zbm-dev/zfsbootmenu

I thought the following was supposed to fix this issue: https://github.com/zbm-dev/zfsbootmenu/commit/84da18e64ebcc0c483e7b2c7d3972f7d91784e63

All release assets, including EFI executables and kernel/initramfs pairs, are signed with signify, which provides a simple method for verifying that the contents of the file are as this project intended. Once you've installed signify (that's left as an exercise, although Void Linux provides the signify package for this purpose), just download the desired assets from the ZFSBootMenu release page, download the file sha256.sig alongside it, and run:

I think the consensus is that you probably shouldn't be installing a ZFS on root using the native installer anymore. They aren't really maintaining the packages that make that work. Instead the suggestion is to go the zfsbootmenu route of installing.

Glad to hear that everything is working for you! I've opened a PR that adds a warning about this condition - it should likely make it into 2.2.0.

You can install following instructions at https://openzfs.github.io/openzfs-docs/Getting%20Started/Debian/Debian%20Bullseye%20Root%20on%20ZFS.html which I've automated with https://github.com/HankB/Linux_ZFS_Root/tree/master/Debian. For scripting, you should also look at https://github.com/zbm-dev/zfsbootmenu. I'd probably go that way if I were starting from scratch.

ZBM provides an amazingly useful script in it's wiki here. This runs when a new kernel is updated by xbps and it snapshots your system before the kernel is installed. This creates a boot environment, and via the magic of ZFS boot environments, allows you to rollback any kernel update to a known, working configuration.

* https://docs.oracle.com/cd/E86824_01/html/E54764/beadm-1m.ht...

> A ZFS boot environment is a bootable clone of the datasets needed to boot the operating system. Creating a BE before performing an upgrade provides a low-cost safeguard: if there is a problem with the update, the system can be rebooted back to the point in time before the upgrade.

* https://klarasystems.com/articles/managing-boot-environments...

Or perhaps:

> In essence, ZFSBootMenu is a small, self-contained Linux system that knows how to find other Linux kernels and initramfs images within ZFS filesystems. When a suitable kernel and initramfs are identified (either through an automatic process or direct user selection), ZFSBootMenu launches that kernel using the kexec command.

* https://github.com/zbm-dev/zfsbootmenu