Re: Still reproducible images on rpm-ostree

[Giuseppe Scrivano <gscrivan redhat com>]

Leandro Santiago <leandrosansilva gmail com> writes:

> Well, I am still facing the issue where the initramfs file created
> during the tree compose phase is always different, therefore having
> different names, and making every update download a whole new file
> (which can up to 40MB in size) even if nothing was changed. The
> initial issue is described in this bug:
> https://bugzilla.redhat.com/show_bug.cgi?id=1235936
>
> It seems the main reason of this issue is that linux uses cpio for
> initramfs and the main implementation of cpio (that creates the
> images) cannot create deterministic images, as it stores the inodes of
> the input files. There is a patched version [1] of cpio which adds an
> --reproducible option and aims to reach those cases. The Guix
> developers also had the same issue, solving it on their cpio
> implementation [2]. Dracut also has a --reproducible option, which
> detects whether cpio supports that giver option.
>
> I haven't tested yet them, but I'd like to know if someone else is
> facing the same problem and if they'd solved it in another way.

yes, that is a known issue and it requires: (1) an updated GNU CPIO,
which has released an updated version like a month ago, the version of
CPIO in Rawhide should already have it; (2) feed "--reproducible" to
Dracut.  Not sure when this is going to happen but it makes sense to
make it the default for Dracut:
http://thread.gmane.org/gmane.linux.kernel.initramfs/4239

Regards,
Giuseppe