From mboxrd@z Thu Jan 1 00:00:00 1970 From: Leo Famulari Subject: Re: [PATCH 4/4] environment: Add '--debug' flag. Date: Wed, 20 Jul 2016 00:17:13 -0400 Message-ID: <20160720041713.GD21435@jasmine> References: <20160719164916.6597-1-david@craven.ch> <20160719164916.6597-5-david@craven.ch> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from eggs.gnu.org ([2001:4830:134:3::10]:36979) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bPiwq-0005pq-DI for guix-devel@gnu.org; Wed, 20 Jul 2016 00:17:29 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1bPiwo-0004gD-9H for guix-devel@gnu.org; Wed, 20 Jul 2016 00:17:27 -0400 Content-Disposition: inline In-Reply-To: List-Id: "Development of GNU Guix and the GNU System distribution." List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: guix-devel-bounces+gcggd-guix-devel=m.gmane.org@gnu.org Sender: "Guix-devel" To: David Craven Cc: guix-devel , Guix-devel On Tue, Jul 19, 2016 at 09:02:58PM +0200, David Craven wrote: > > 1. I'd like to use overlay fs (like docker) and create a new overlay > > for each phase to easily revert a phase. > > I think this might also help to debug build reproducibility issues, by > finding out which phase is introducing them. (Or is it always > obvious?) In general, the idea of being able to move between phases like that is really cool. I don't have any experience with overlayfs, so I can't comment on that detail. I wouldn't say it's ever obvious where a reproducibility bug is introduced, but many of them are timestamps, sometimes with an English string attached, and that code is usually easy to find. Thankfully, the Reproducible Builds project has a useful database of bugs they've found: https://anonscm.debian.org/git/reproducible/notes.git