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Show HN: Zectl – ZFS Boot Environment Manager for Linux

119 points by johnramsden 7y ago

_jal 7y ago
This looks nice. Going to have to give it a try. I'd love to see automated ZFS-on-root setup, but suspect that'll have to come from Canonical if we ever get it.
- johnramsden 7y ago
  In 20.04 they will have ZFS on root with BEs as an install option, looking forward to seeing the first major Linux distro making it available as a default.
  - pmarreck 7y ago
    Currently running that exact setup, it’s sweet
- vbezhenar 7y ago
  I'm surprised that they did not do that yet. While ZFS license status is questionable, Canonical seems to be sure that everything's OK, so they should embrace its technical superiority. Something like full system rollback after bad update is trivial with snapshots and it's extremely useful feature.
  - johnramsden 7y ago
    Looks to be that's what they have done. They've developed a new tool called `zsys` https://github.com/ubuntu/zsys https://github.com/ubuntu/zsys which will help with system administration, rollbacks, auto snapshots before and after package changes. I believe it will also support boot environments.
- rkwasny 7y ago
  You can do automated ZFS-on-root installs through MAAS https://maas.io/ https://maas.io/
- HankB99 7y ago
  I thought that Ubuntu was already capable of doing this in the latest release (19.10.) There are third party scripts to accomplish this. I would look at https://github.com/saveriomiroddi/zfs-installer https://github.com/saveriomiroddi/zfs-installer. The only reason I have not used it is that I had already written my own https://github.com/HankB/Linux_ZFS_Root https://github.com/HankB/Linux_ZFS_Root. And in this case, better the devil I know. (I'm presently updating my script to follow the most recent instructions at https://github.com/openzfs/zfs/wiki/Debian-Buster-Root-on-ZFS. https://github.com/openzfs/zfs/wiki/Debian-Buster-Root-on-ZF...) ZFS-installer appears to be more mature and is seeing more effort than mine. Perhaps I should give it a try.
unixhero 7y ago
With encryption support?
- johnramsden 7y ago
  I haven't tried it myself with encryption, but I can't see it making a difference. The bootloader, and initial ZFS setup will be what needs to be changed to facilitate encryption.
  - kitotik 7y ago
    Hmm, how/when/where would the ‘zfs load-key’ happen? I only know how to use the systemd-ask-password hack to decrypt non-root datasets, but can’t get my head around how that would work with fully encrypted root dataset.
    - Gigamo 7y ago
      If you're using Arch, the zfs hook that comes with the archzfs package takes care of this: https://github.com/archzfs/zfs-utils/blob/master/zfs-utils.initcpio.hook#L28 https://github.com/archzfs/zfs-utils/blob/master/zfs-utils.i...
    - kevans91 7y ago
      Presumably it would be like FreeBSD's GELI, where early boot stuff would need to detect that it's looking at an encrypted root and know to prompt. In theory, this is relatively straightforward- with boot environments, the zpool bootfs property indicates the root dataset, so I wouldn't think you need to look too far. [edit: this is done in our loader, so presumably you'd use grub?]
cyberpunk 7y ago
Finally. I got used to this on solaris 10 and missed it until FreeBSD got it.. ZFS and beadm are the included in the reasons i continue to run FreeBSD as a workstation, but these days with k8s and such I do tend to run a lot of linux VMs to do my daily work (devops stuff)... The work lappy runs ubuntu with zfs on root, and it's pretty seamless, I'm very much onboard with it having boot environments! (zsys)
- blue1 7y ago
  Zfs on a laptop means you run zfs with a single disk?
  - 0xcde4c3db 7y ago
    This is not unheard of among FreeBSD users. Most of ZFS's features do not require (or even necessarily benefit from) multiple disks.
    - gigatexal 7y ago
      Yup checksumming and snapshots and compression and at rest encryption are amazing to name a few
  - aidenn0 7y ago
    Not necessarily, my laptop has 2 M2 slots.
  - yjftsjthsd-h 7y ago
    They make adaptors that let you replace the optical drive with another SATA drive. But my FreeBSD laptop has one disk and it's fine. You don't have redundancy, but you still get all the other features (snapshots, clones, compression), and even if it can't correct errors it will still catch data errors which is more than most other filesystems will do.
  - andoriyu 7y ago
    I ran ZFS with a single disk on a laptop. What's wrong with that?
kevans91 7y ago
Oh, this is cool! We'll need to check out this plugin mechanism as a thought for bectl -- it's fairly inflexible at the moment. libze_util_temporary_mount would be a good candidate for using (or being replaced by?) the recently-introduced zfs_mount_at in libzfs once that's widely available enough. That was a fairly trivial addition to libzfs that was initially made to support libbe's be_mount(), which previously used the effectively non-portable amount() [post-mortem: should read zmount, but autocorrect is alwayscorrect]
- johnramsden 7y ago
  loader ZFS integration is really great on FreeBSD, do people occasionally want to use something else? Is that why you would consider looking to support other options? Really would be nice to see loader ported to Linux - I know it was recently brought over to Solaris. Maybe a project for another day... Thanks for the tip, the temporary mounting seems a bit like a hack so that's good to know there's a better option.
  - kevans91 7y ago
    I've seen the occasional rumbling about folks wanting to use grub for one reason or another- while not necessarily ideal (having the caveats of a non-loader environment), I can see the value in it if you really don't need the amenities loader offers (debugging support, kmods).
acd 7y ago
Big thanks to the developers/John for creating ZFS Linux boot manager!
mskalski 7y ago
Looks cool. Currently only one machine which I have with zfs is NixOS, which has it own mechanism to handle such versioning, or do you see some advantages of using zfs approach?
- johnramsden 7y ago
  I used to use NixOS, and I do have some of the best ZFS support out of the box I've seen on Linux. I'm not sure if the approach of using zfs boot environments would play well with NixOS considering how they manage the configuration and rollbacks separately. They also manage the bootloader, so I don't know if the changes would survive. Something could probably be set up to work, but it would probably feel as though you were working against the intended way the system should work.

119 points by johnramsden 7y ago

_jal 7y ago

This looks nice. Going to have to give it a try. I'd love to see automated ZFS-on-root setup, but suspect that'll have to come from Canonical if we ever get it.

johnramsden 7y ago
In 20.04 they will have ZFS on root with BEs as an install option, looking forward to seeing the first major Linux distro making it available as a default.
- pmarreck 7y ago
  Currently running that exact setup, it’s sweet
vbezhenar 7y ago
I'm surprised that they did not do that yet. While ZFS license status is questionable, Canonical seems to be sure that everything's OK, so they should embrace its technical superiority. Something like full system rollback after bad update is trivial with snapshots and it's extremely useful feature.
- johnramsden 7y ago
  Looks to be that's what they have done. They've developed a new tool called `zsys` https://github.com/ubuntu/zsys https://github.com/ubuntu/zsys which will help with system administration, rollbacks, auto snapshots before and after package changes. I believe it will also support boot environments.
rkwasny 7y ago
You can do automated ZFS-on-root installs through MAAS https://maas.io/ https://maas.io/
HankB99 7y ago
I thought that Ubuntu was already capable of doing this in the latest release (19.10.) There are third party scripts to accomplish this. I would look at https://github.com/saveriomiroddi/zfs-installer https://github.com/saveriomiroddi/zfs-installer. The only reason I have not used it is that I had already written my own https://github.com/HankB/Linux_ZFS_Root https://github.com/HankB/Linux_ZFS_Root. And in this case, better the devil I know. (I'm presently updating my script to follow the most recent instructions at https://github.com/openzfs/zfs/wiki/Debian-Buster-Root-on-ZFS. https://github.com/openzfs/zfs/wiki/Debian-Buster-Root-on-ZF...) ZFS-installer appears to be more mature and is seeing more effort than mine. Perhaps I should give it a try.

unixhero 7y ago

With encryption support?

johnramsden 7y ago
I haven't tried it myself with encryption, but I can't see it making a difference. The bootloader, and initial ZFS setup will be what needs to be changed to facilitate encryption.
- kitotik 7y ago
  Hmm, how/when/where would the ‘zfs load-key’ happen? I only know how to use the systemd-ask-password hack to decrypt non-root datasets, but can’t get my head around how that would work with fully encrypted root dataset.
  - Gigamo 7y ago
    If you're using Arch, the zfs hook that comes with the archzfs package takes care of this: https://github.com/archzfs/zfs-utils/blob/master/zfs-utils.initcpio.hook#L28 https://github.com/archzfs/zfs-utils/blob/master/zfs-utils.i...
  - kevans91 7y ago
    Presumably it would be like FreeBSD's GELI, where early boot stuff would need to detect that it's looking at an encrypted root and know to prompt. In theory, this is relatively straightforward- with boot environments, the zpool bootfs property indicates the root dataset, so I wouldn't think you need to look too far. [edit: this is done in our loader, so presumably you'd use grub?]

cyberpunk 7y ago

Finally. I got used to this on solaris 10 and missed it until FreeBSD got it.. ZFS and beadm are the included in the reasons i continue to run FreeBSD as a workstation, but these days with k8s and such I do tend to run a lot of linux VMs to do my daily work (devops stuff)... The work lappy runs ubuntu with zfs on root, and it's pretty seamless, I'm very much onboard with it having boot environments! (zsys)

blue1 7y ago
Zfs on a laptop means you run zfs with a single disk?
- 0xcde4c3db 7y ago
  This is not unheard of among FreeBSD users. Most of ZFS's features do not require (or even necessarily benefit from) multiple disks.
  - gigatexal 7y ago
    Yup checksumming and snapshots and compression and at rest encryption are amazing to name a few
- aidenn0 7y ago
  Not necessarily, my laptop has 2 M2 slots.
- yjftsjthsd-h 7y ago
  They make adaptors that let you replace the optical drive with another SATA drive. But my FreeBSD laptop has one disk and it's fine. You don't have redundancy, but you still get all the other features (snapshots, clones, compression), and even if it can't correct errors it will still catch data errors which is more than most other filesystems will do.
- andoriyu 7y ago
  I ran ZFS with a single disk on a laptop. What's wrong with that?

kevans91 7y ago

Oh, this is cool! We'll need to check out this plugin mechanism as a thought for bectl -- it's fairly inflexible at the moment. libze_util_temporary_mount would be a good candidate for using (or being replaced by?) the recently-introduced zfs_mount_at in libzfs once that's widely available enough. That was a fairly trivial addition to libzfs that was initially made to support libbe's be_mount(), which previously used the effectively non-portable amount() [post-mortem: should read zmount, but autocorrect is alwayscorrect]

johnramsden 7y ago
loader ZFS integration is really great on FreeBSD, do people occasionally want to use something else? Is that why you would consider looking to support other options? Really would be nice to see loader ported to Linux - I know it was recently brought over to Solaris. Maybe a project for another day... Thanks for the tip, the temporary mounting seems a bit like a hack so that's good to know there's a better option.
- kevans91 7y ago
  I've seen the occasional rumbling about folks wanting to use grub for one reason or another- while not necessarily ideal (having the caveats of a non-loader environment), I can see the value in it if you really don't need the amenities loader offers (debugging support, kmods).

acd 7y ago

Big thanks to the developers/John for creating ZFS Linux boot manager!

mskalski 7y ago

Looks cool. Currently only one machine which I have with zfs is NixOS, which has it own mechanism to handle such versioning, or do you see some advantages of using zfs approach?

johnramsden 7y ago
I used to use NixOS, and I do have some of the best ZFS support out of the box I've seen on Linux. I'm not sure if the approach of using zfs boot environments would play well with NixOS considering how they manage the configuration and rollbacks separately. They also manage the bootloader, so I don't know if the changes would survive. Something could probably be set up to work, but it would probably feel as though you were working against the intended way the system should work.