Subject: bug#22962: Something keeps overwriting /etc/hosts

From: Alex Kost <[email-masked]>
Date: Thu, 10 Mar 2016 11:39:00 +0300

Leo Famulari (2016-03-10 04:43 +0300) wrote:

> On Thu, Mar 10, 2016 at 12:28:11AM +0100, Danny Milosavljevic wrote:
>> If I make it immutable, I get the following message on guix system reconfigure ... :
>>
>>   guix system: error: copy-file: Permission denied: "/etc/hosts"
>>
>> Aha!
>
> I think that on GuixSD, the hosts file is generated from the system
> configuration, specifically the 'hosts-file' field, which is mentioned
> in section 7.2.2 Operating System Reference [0].
>
> I assume that the resulting file is recreated each time you reconfigure.
>
> In that case, you'd want to leave the file /etc/hosts alone, and make
> your changes in the operating system configuration.
>
> I say "I think" and "I assume" because I haven't actually used
> 'hosts-file' yet, nor have I looked at that part of the code.

You are absolutely right!  On GuixSD, to modify /etc/hosts a user need
to adjust his/her system config.

Danny, you can keep your hosts file wherever you want, let's say
"~/my-config/hosts"; and you can add this line to your operating-system
declaration:

  (hosts-file (local-file (string-append (getenv "HOME")
                                         "/my-config/hosts")))

After reconfiguring your system, this file will be put into the store,
and /etc/hosts will have the same contents after reboot.

Moreover, every time you change this file and make a new system, a new
version of "hosts" will be put to the store.  So if you boot into some
old system, it will be booted with the hosts file that was used at that
time (as you can see, every system in /var/guix/profiles, has its own
"etc/hosts").

-- 
Alex