On Fri, May 15, 2020 at 7:16 AM antlists <antli...@youngman.org.uk> wrote: > > On 15/05/2020 11:20, Neil Bothwick wrote: > > > > Or you can create a custom module, they are just shell scripts. I recall > > reading a blog post by Rich on how to do this a few years ago. > > > My custom module calls a shell script, so it shouldn't be that hard from > what you say. I then need to make sure the program it invokes > (integritysetup) is in the initramfs?
The actual problem that this module solves is no-doubt long solved upstream, but here is the blog post on dracut modules (which is fairly well-documented in the official docs as well): https://rich0gentoo.wordpress.com/2012/01/21/a-quick-dracut-module/ Basically you have a shell script that tells dracut when building the initramfs to include in it whatever you need. Then you have the phase hooks that actually run whatever you need to run at the appropriate time during boot (presumably before the mdadm stuff runs). My example doesn't install any external programs, but there is a simple syntax for that. If your module is reasonably generic you could probably get upstream to merge it as well. Good luck with it, and I'm curious as to how you like this setup vs something more "conventional" like zfs/btrfs. I'm using single-volume zfs for integrity for my lizardfs chunkservers and it strikes me that maybe dm-integrity could accomplish the same goal with perhaps better performance (and less kernel fuss). I'm not sure I'd want to replace more general-purpose zfs with this, though the flexibility of lvm+mdadm is certainly attractive. -- Rich
