[OE-core] [PATCH 0/4] Reproducible binaries

[Bystricky, Juro]

SOURCE_DATE_EPOCH is not the issue here. There are few other places that require timestamps.
SOURCE_DATE_EPOCH is determined as the mktime of the youngest source file or if git repo present
as the time of the top commit. (Otherwise it defaults to 0). This needs to be done per package.
I'll send in a new set of patches, with additional timestamps related variables that will allow user customization.



________________________________________
From: Joshua Lock [joshua.g.lock at linux.intel.com]
Sent: Thursday, April 27, 2017 2:50 AM
To: Bystricky, Juro; Martin Jansa
Cc: jurobystricky at hotmail.com; Patches and discussions about the oe-core layer
Subject: Re: [OE-core] [PATCH 0/4] Reproducible binaries

On Wed, 2017-04-26 at 19:50 +0000, Bystricky, Juro wrote:
> > I wasnted to say "passing the seed value" through some separate
> > variable
> > which is easy to override from somewhere else.
> >
> > e.g.
> > export PRELINK_TIMESTAMP=`git log -1 --pretty=%ct `
> >
> > in image-prelink.bbclass:prelink_image() is a bit difficult to
> > override.
> >
>
> I think it is best to keep all reproducible build related variables
> gathered together,
> so bitbake.conf seems like a natural place (same place as the
> variable BUILD_REPRODUCIBLE_BINARIES),
> i.e something like:
>
> PRELINK_TIMESTAMP ??=`git log -1 --pretty=%ct `
>
> A single "general purpose" fallback timestamp variable (not specific
> to prelinking) would be my
> preference. Unfortunately, the timestamps may need to come in various
> different formats...

One option for a single general purpose timestamp variable is just to
use a static value. Guix[1] just set the value of SOURCE_DATE_EPOCH to
1[2].

Joshua

1. https://www.gnu.org/software/guix/
2. http://git.savannah.gnu.org/cgit/guix.git/tree/guix/build/gnu-build-
system.scm#n42