Bug#900918: debian-installer: Please make the generated images reproducible

[Cyril Brulebois]

Control: tag -1 pending

Cyril Brulebois <kibi at debian.org> (2019-01-19):
> The mini.iso has apparently other changes… I'm attaching the diffoscope
> output. Could this be because of missing tweaks to the xorriso calls in
> build/config/x86.cfg? (In which case build/config/arm.cfg might need an
> update as well.) Checking all MINIISO occurrences might also make sense
> I suppose?

FWIW, dropping all fontconfig-related bits (see attached patch) makes it
possible to confirm only mini.iso (regular and gtk ones) are showing
differences now:

    installer-amd64/20190119/images/MD5SUMS
    installer-amd64/20190119/images/netboot/gtk/mini.iso
    installer-amd64/20190119/images/netboot/mini.iso
    installer-amd64/20190119/images/SHA256SUMS


I had purged the pigz package during my experiments, just to be sure it
wouldn't interfere:

    build/Makefile:gzip = $(shell which pigz >/dev/null 2>&1 && echo "pigz -n -T" || echo "gzip -n")

(Including lintian runtime, using pigz on a 8-way machine cuts real time
from 8m8s to 4m23s.)

Checking what happens, and forgetting about the aforementioned mini.iso
images temporarily, it seems successive builds with pigz lead to the
same results. But those aren't the same as the results generated with
gzip. I don't suppose this is going to be a particularly huge problem
though?


Anyway, summarizing: likely more work to be done on the xorriso front,
(on the debian-installer side) for the mini.iso images produced for
netbooting; and fontconfig needs to get fixed in some way at some point
(but I know it's been a long run as well…); but all the rest looks good.

Pushing once I have updated the changelog; marking as pending, thanks!


Cheers,
-- 
Cyril Brulebois (kibi at debian.org)            <https://debamax.com/>
D-I release manager -- Release team member -- Freelance Consultant
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