From mboxrd@z Thu Jan 1 00:00:00 1970 From: 7e9wc56emjakcm@s.rendaw.me Subject: Re: Remounting tmpfs Date: Wed, 10 Apr 2019 00:24:32 +0900 Message-ID: References: <80844c75-50c6-ff82-6693-db6af0f10551@fastmail.com> <877ec3fcnt.fsf@gnu.org> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit Return-path: Received: from eggs.gnu.org ([209.51.188.92]:37254) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from <7e9wc56emjakcm@s.rendaw.me>) id 1hDsc6-0005uf-TK for help-guix@gnu.org; Tue, 09 Apr 2019 11:24:43 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from <7e9wc56emjakcm@s.rendaw.me>) id 1hDsc5-00061T-Uf for help-guix@gnu.org; Tue, 09 Apr 2019 11:24:42 -0400 In-Reply-To: <877ec3fcnt.fsf@gnu.org> Content-Language: en-US List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: help-guix-bounces+gcggh-help-guix=m.gmane.org@gnu.org Sender: "Help-Guix" To: =?UTF-8?Q?Ludovic_Court=c3=a8s?= Cc: help-guix@gnu.org On 4/9/19 11:58 PM, Ludovic Courtès wrote: > Hello, > > 7e9wc56emjakcm@s.rendaw.me skribis: > >> On a system I'm porting to guix I have 2GB tmpfs with subdirectories >> like /tmpfs/etc that I remount to /etc with an overlay filesystem. >> >> The current way I do this in systemd is making a service dependency >> between the /tmpfs and /etc mounts that mkdirs /tmpfs/etc and >> /tmpfs/etc_work, but AFAICT filesystem definitions in guix can only have >> filesystem dependencies. >> >> Are there any other ways I can do this without copying/pasting/modifying >> gobs of core guix code into my system definition? Like somehow >> appending (mkdir /tmpfs/etc) onto the tmpfs filesystem service start >> procedure or something. > In Guix /etc is mostly populated by “activation programs”, which are > generated from your config. So I’m not sure what you describe would > make much sense. So if /etc can be read-only and boot I'm probably fine... my experience with other distros was that some other processes needed to write to it.  Ex: modifying resolv.conf. > Now, you could try to add a file system declaration that mounts /etc, > with (needed-for-boot? #t). My goal is to have a read-only / mount with the ability for programs to make temporary modifications for operational purposes when necessary, in limited scopes (like /etc).  Can you elaborate on what you're suggesting here?  Mounting something other than the overlayfs on /etc would hide the system config files.  I might be able to use another mount to create a pseudo- /tmpfs/etc_work subdirectory but it sounds kind of wormy and overlayfs requires the upper dir and workdir to be the same filesystem which I think precludes doing any mounting for those subdirectories. Thanks for the suggestions!