5 ms·

how exactly does nix prevents updates from breaking your system? arch is as close to upstream as possible, so you're not updating from upstream either... are yo

how exactly does nix prevents updates from breaking your system? arch is as close to upstream as possible, so you're not updating from upstream either... are you just... not updating?

mrslave 2y ago
It's more like the whole upgrade is either successful, or it is not, and you are not left in an indeterminate state. E.g. A depends on B. In a large update, B updates, something unrelated fails to install and the update fails, and now A doesn't run because it wasn't upgraded and the still installed old version of A depends on the no longer available previous version of B. In NixOS, you either enter the new environment with all packages updated, or you don't. In the situation where you discover run-time - not install-time - errors, you can simply roll back to the previous set of packages. If the new packages cause a system crash, you can enter previous states from the bootloader. Now none of this magically solves the software defects themselves. But it gives you a consistent system state that can be transactionally upgraded, or reentered at any time. And then you can raise the appropriate bug tickets. Your system configuration is in a single file and the need to reconfigure different services in a particular order is gone. Also your dependencies are all nicely pinned with Flakes. This makes importing arbitrary dependencies - open-source or proprietary - a breeze. This has removed any previous appetite we had for a monorepo, which was primarily to ease access to our other libraries. It's all very nice, once you are over the not insubstantial learning curve that is.
- 1oooqooq 2y ago
  i guess i cannot imagine the kind of problems you were having before :) but from the description they seem runtime errors. do you have a functional test of sorts after nix creates the new state?
  - mbrock 2y ago
    Look at Debian's official instructions for how to upgrade to a new major release. The wiki page begins with this casual disclaimer: "DANGER!!! DANGER!!! DANGER!!! DANGER!!! DANGER!!! DANGER!!! DANGER!!! DANGER!!! DANGER!!! DANGER!!!" The release notes for each version has the detailed instructions for how to upgrade from the previous version. They very strongly emphasize backing up the entire system, because the upgrade process is absolutely not guaranteed to leave the computer in a state that works correctly or boots at all, and there is no way to undo it. That's what's different about NixOS: if the new configuration doesn't work properly, you can just choose the previous configuration in the bootloader menu. It's as straightforward and foolproof as switching to another branch in a Git repository. The whole point of NixOS is that you can have any number of system configurations in the Nix store and switch between them in a way that's atomic in the transactional sense. If you know how Nix works, you can feel safe turning off the power supply at any point during a full system upgrade. You'll never end up in a state where half of the packages are upgraded. It's either upgraded or not. As far as I know there's no other distribution that works like this other than GuixSD.
  - JamesSwift 2y ago
    NixOS supports adding tests which are selenium-style integration tests run on VMs
- pdimitar 2y ago
  Yes, the updates treated like a DB transaction are the main draw of Nix and I agree they're nice. However, Fedora and recently Manjaro started offering the so-called "immutable" versions that do nearly the same: you can install and delete and do whatever you like but you also have to explicitly opt in to commit those changes to your bootable image. If you don't do it they're just discarded after you reboot. That's quite awesome and saves me from 99% of the problem you described... without having to learn the Nix's weird language or be willing to read cryptic error messages and get roasted on Reddit for not knowing them by heart.
yjftsjthsd-h 2y ago
You can update both of them, but Arch breaks then you have to figure out how to manually roll back the packages that broke it. If NixOS breaks, you reboot and select the previous generation and it's all reversed for you.
- 1oooqooq 2y ago
  maybe you want manjaro (week late arch) and dual root.
  - yjftsjthsd-h 2y ago
    Has anyone implemented A/B root on Arch or a derivative?
    - RandomThoughts3 2y ago
      If your filesystem is btrfs, you can use snapper and a pacman hook to do something equivalent but using less storage. See https://wiki.archlinux.org/title/Snapper https://wiki.archlinux.org/title/Snapper
llm_trw 2y ago
Updates are reversible and you have a list of every update you have ever tried to revert to.
JZL003 2y ago
Not quite the same but very useful for me. Sometimes small patches to programs have big usability wins. In nix you can still update automatically, it adds your patch, automatically downloads the programs needed to compile (but still can be garbage collected afterwards), compiles and done Maybe not great for production but for personal use, since I guess this patch could break. But in exchange for a few times it breaks, I get automatic patched updated (Except for emacs where takes 40 minutes to compile, but schedule updated for night)
petterroea 2y ago
My general experience with Arch is that the up-to-date-ness is a double-edged sword, and you some times hit new bugs or incompatabilities. If it happens in nix i can simply just revert - you can select which OS build version you want to boot at startup - and wait a few days. And for my eGPU setup it also gives me a lot more confidence to tinker and reboot - the barrier for me to do so is a lot lower when I know i can simply boot an older build of my OS instead of having to whip out the arch installer USB and arch-chroot into my root drive to fix a bricked install that no longer boots.
- aitchnyu 2y ago
  There is a Utopia of rolling release and Snapper/Btrfs which takes a snapshot of / each time you use your package manager so you can roll back. But SpiralLinux(can be Sid based, Snapper OOTB) was infuriating with my Nvidia/5k screen and Cachy(Arch based with Calamares) didnt install. I'm too lazy to do it with a major distro and I download prebuilt debs/rpms and dont want to fight Opensuse Leap which invented Snapper.

how exactly does nix prevents updates from breaking your system? arch is as close to upstream as possible, so you're not updating from upstream either... are you just... not updating?

mrslave 2y ago

It's more like the whole upgrade is either successful, or it is not, and you are not left in an indeterminate state. E.g. A depends on B. In a large update, B updates, something unrelated fails to install and the update fails, and now A doesn't run because it wasn't upgraded and the still installed old version of A depends on the no longer available previous version of B. In NixOS, you either enter the new environment with all packages updated, or you don't. In the situation where you discover run-time - not install-time - errors, you can simply roll back to the previous set of packages. If the new packages cause a system crash, you can enter previous states from the bootloader. Now none of this magically solves the software defects themselves. But it gives you a consistent system state that can be transactionally upgraded, or reentered at any time. And then you can raise the appropriate bug tickets. Your system configuration is in a single file and the need to reconfigure different services in a particular order is gone. Also your dependencies are all nicely pinned with Flakes. This makes importing arbitrary dependencies - open-source or proprietary - a breeze. This has removed any previous appetite we had for a monorepo, which was primarily to ease access to our other libraries. It's all very nice, once you are over the not insubstantial learning curve that is.

1oooqooq 2y ago
i guess i cannot imagine the kind of problems you were having before :) but from the description they seem runtime errors. do you have a functional test of sorts after nix creates the new state?
- mbrock 2y ago
  Look at Debian's official instructions for how to upgrade to a new major release. The wiki page begins with this casual disclaimer: "DANGER!!! DANGER!!! DANGER!!! DANGER!!! DANGER!!! DANGER!!! DANGER!!! DANGER!!! DANGER!!! DANGER!!!" The release notes for each version has the detailed instructions for how to upgrade from the previous version. They very strongly emphasize backing up the entire system, because the upgrade process is absolutely not guaranteed to leave the computer in a state that works correctly or boots at all, and there is no way to undo it. That's what's different about NixOS: if the new configuration doesn't work properly, you can just choose the previous configuration in the bootloader menu. It's as straightforward and foolproof as switching to another branch in a Git repository. The whole point of NixOS is that you can have any number of system configurations in the Nix store and switch between them in a way that's atomic in the transactional sense. If you know how Nix works, you can feel safe turning off the power supply at any point during a full system upgrade. You'll never end up in a state where half of the packages are upgraded. It's either upgraded or not. As far as I know there's no other distribution that works like this other than GuixSD.
- JamesSwift 2y ago
  NixOS supports adding tests which are selenium-style integration tests run on VMs
pdimitar 2y ago
Yes, the updates treated like a DB transaction are the main draw of Nix and I agree they're nice. However, Fedora and recently Manjaro started offering the so-called "immutable" versions that do nearly the same: you can install and delete and do whatever you like but you also have to explicitly opt in to commit those changes to your bootable image. If you don't do it they're just discarded after you reboot. That's quite awesome and saves me from 99% of the problem you described... without having to learn the Nix's weird language or be willing to read cryptic error messages and get roasted on Reddit for not knowing them by heart.

yjftsjthsd-h 2y ago

You can update both of them, but Arch breaks then you have to figure out how to manually roll back the packages that broke it. If NixOS breaks, you reboot and select the previous generation and it's all reversed for you.

1oooqooq 2y ago
maybe you want manjaro (week late arch) and dual root.
- yjftsjthsd-h 2y ago
  Has anyone implemented A/B root on Arch or a derivative?
  - RandomThoughts3 2y ago
    If your filesystem is btrfs, you can use snapper and a pacman hook to do something equivalent but using less storage. See https://wiki.archlinux.org/title/Snapper https://wiki.archlinux.org/title/Snapper

llm_trw 2y ago

Updates are reversible and you have a list of every update you have ever tried to revert to.

JZL003 2y ago

Not quite the same but very useful for me. Sometimes small patches to programs have big usability wins. In nix you can still update automatically, it adds your patch, automatically downloads the programs needed to compile (but still can be garbage collected afterwards), compiles and done Maybe not great for production but for personal use, since I guess this patch could break. But in exchange for a few times it breaks, I get automatic patched updated (Except for emacs where takes 40 minutes to compile, but schedule updated for night)

petterroea 2y ago

My general experience with Arch is that the up-to-date-ness is a double-edged sword, and you some times hit new bugs or incompatabilities. If it happens in nix i can simply just revert - you can select which OS build version you want to boot at startup - and wait a few days. And for my eGPU setup it also gives me a lot more confidence to tinker and reboot - the barrier for me to do so is a lot lower when I know i can simply boot an older build of my OS instead of having to whip out the arch installer USB and arch-chroot into my root drive to fix a bricked install that no longer boots.

aitchnyu 2y ago
There is a Utopia of rolling release and Snapper/Btrfs which takes a snapshot of / each time you use your package manager so you can roll back. But SpiralLinux(can be Sid based, Snapper OOTB) was infuriating with my Nvidia/5k screen and Cachy(Arch based with Calamares) didnt install. I'm too lazy to do it with a major distro and I download prebuilt debs/rpms and dont want to fight Opensuse Leap which invented Snapper.