GNU bug report logs - #45302
Avahi substitute discovery keeps trying to ping unaccessible servers

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Message #5 received at submit <at> debbugs.gnu.org (full text, mbox):

From: Pierre Neidhardt <mail <at> ambrevar.xyz>
To: bug-guix <at> gnu.org
Subject: Avahi substitute discovery keeps trying to ping unaccessible servers
Date: Thu, 17 Dec 2020 18:40:33 +0100

[Message part 1 (text/plain, inline)]

I've set up my desktop and laptop to use the new substitute discovery
feature, it's awesome!

However, when I put my desktop to sleep and run a Guix command on my
laptop that requires access to a sbustitute server, I see this:

--8<---------------cut here---------------start------------->8---
$ guix build ncdu
substitute: guix substitute: warning: 10.0.0.5: connection failed: No route to host
substitute: updating substitutes from 'http://ci.guix.gnu.org'... 100.0%
0.0 MB will be downloaded:
   /gnu/store/p70r4maqgh6ghl25h5a99w7sf1jidap8-ncdu-1.15.1
substituting /gnu/store/p70r4maqgh6ghl25h5a99w7sf1jidap8-ncdu-1.15.1...
--8<---------------cut here---------------end--------------->8---

The warning

--8<---------------cut here---------------start------------->8---
substitute: guix substitute: warning: 10.0.0.5: connection failed: No route to host
--8<---------------cut here---------------end--------------->8---

pops up on every download, which adds some 2s delay each time.  This
makes the whole process much slower.

For your information, Avahi does not find my desktop:

--8<---------------cut here---------------start------------->8---
$ sudo avahi-browse -al
Password: 
+ wlp2s0 IPv6 FOO___s MacBook Pro                        _companion-link._tcp local
+ wlp2s0 IPv4 FOO___s MacBook Pro                        _companion-link._tcp local
  C-c C-cGot SIGINT, quitting.
--8<---------------cut here---------------end--------------->8---

-- 
Pierre Neidhardt
https://ambrevar.xyz/

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Message #8 received at 45302 <at> debbugs.gnu.org (full text, mbox):

From: Pierre Neidhardt <mail <at> ambrevar.xyz>
To: 45302 <at> debbugs.gnu.org
Subject: Re: bug#45302: Acknowledgement (Avahi substitute discovery keeps
 trying to ping unaccessible servers)
Date: Thu, 17 Dec 2020 19:33:01 +0100

[Message part 1 (text/plain, inline)]

I still witness this issue after restarting my laptop.
Looks like Avahi remembers the discovery across restarts.

-- 
Pierre Neidhardt
https://ambrevar.xyz/

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Message #11 received at 45302 <at> debbugs.gnu.org (full text, mbox):

From: Maxim Cournoyer <maxim.cournoyer <at> gmail.com>
To: Pierre Neidhardt <mail <at> ambrevar.xyz>
Cc: 45302 <at> debbugs.gnu.org
Subject: Re: bug#45302: Avahi substitute discovery keeps trying to ping
 unaccessible servers
Date: Mon, 21 Dec 2020 22:25:03 -0500

Hello,

Pierre Neidhardt <mail <at> ambrevar.xyz> writes:

> I've set up my desktop and laptop to use the new substitute discovery
> feature, it's awesome!
>
> However, when I put my desktop to sleep and run a Guix command on my
> laptop that requires access to a sbustitute server, I see this:
>
> $ guix build ncdu
> substitute: guix substitute: warning: 10.0.0.5: connection failed: No route to host
> substitute: updating substitutes from 'http://ci.guix.gnu.org'... 100.0%
> 0.0 MB will be downloaded:
>    /gnu/store/p70r4maqgh6ghl25h5a99w7sf1jidap8-ncdu-1.15.1
> substituting /gnu/store/p70r4maqgh6ghl25h5a99w7sf1jidap8-ncdu-1.15.1...
>
>
> The warning
>
> substitute: guix substitute: warning: 10.0.0.5: connection failed: No route to host
>
>
> pops up on every download, which adds some 2s delay each time.  This
> makes the whole process much slower.
>
> For your information, Avahi does not find my desktop:
>
> $ sudo avahi-browse -al
> Password: 
> + wlp2s0 IPv6 FOO___s MacBook Pro                        _companion-link._tcp local
> + wlp2s0 IPv4 FOO___s MacBook Pro                        _companion-link._tcp local
>   C-c C-cGot SIGINT, quitting.

This reminds me of https://issues.guix.gnu.org/30290.  Perhaps if we can
fix that one it'd make this one go away too?.  I was thinking of having
a simple mean to reduce the request attempts on servers down for a long
while, such as entering dead periods (breaks): "I've tried X times, it
doesn't respond, I give up for the next Y minutes"; allowing for X and Y
to be configured via the <guix-publish-configuration> record.

Do you think this would help?

Maxim

Message #14 received at 45302 <at> debbugs.gnu.org (full text, mbox):

From: Pierre Neidhardt <mail <at> ambrevar.xyz>
To: Maxim Cournoyer <maxim.cournoyer <at> gmail.com>
Cc: 45302 <at> debbugs.gnu.org
Subject: Re: bug#45302: Avahi substitute discovery keeps trying to ping
 unaccessible servers
Date: Tue, 22 Dec 2020 10:45:07 +0100

[Message part 1 (text/plain, inline)]

Hi Maxim!

Thanks for the suggestion!
I'm a bit ignorant here, but my guess is that yes, it would help!

Cheers!

-- 
Pierre Neidhardt
https://ambrevar.xyz/

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Message #17 received at 45302 <at> debbugs.gnu.org (full text, mbox):

From: Mathieu Othacehe <othacehe <at> gnu.org>
To: Pierre Neidhardt <mail <at> ambrevar.xyz>
Cc: 45302 <at> debbugs.gnu.org
Subject: Re: bug#45302: Avahi substitute discovery keeps trying to ping
 unaccessible servers
Date: Mon, 11 Jan 2021 14:24:10 +0100

Hello Pierre,

> I've set up my desktop and laptop to use the new substitute discovery
> feature, it's awesome!

Glad you like it, and sorry for the late answer.

> substitute: guix substitute: warning: 10.0.0.5: connection failed: No route to host

Once your laptop goes to sleep, Avahi should detect that the publish
service is gone and remove it from the cache at
/var/guix/discovery/publish.

I'm having troubles reproducing it at home. Could you please run
"avahi-browse -a" on your desktop, put your laptop to sleep, and check
if the publish server disappears this way:

--8<---------------cut here---------------start------------->8---
- enp7s0f0 IPv6 guix-publish-cervin                           _guix_publish._tcp   local
- enp7s0f0 IPv4 guix-publish-cervin                           _guix_publish._tcp   local
--8<---------------cut here---------------end--------------->8---

Regarding the reboot issue, that's because the cache wasn't cleaned-up,
it should by fixed with: ee94cd265e03d12eeeccf58cbaf74b90008fcd14.

Thanks,

Mathieu

Message #20 received at 45302 <at> debbugs.gnu.org (full text, mbox):

From: Pierre Neidhardt <mail <at> ambrevar.xyz>
To: Mathieu Othacehe <othacehe <at> gnu.org>
Cc: 45302 <at> debbugs.gnu.org
Subject: Re: bug#45302: Avahi substitute discovery keeps trying to ping
 unaccessible servers
Date: Mon, 18 Jan 2021 12:14:10 +0100

[Message part 1 (text/plain, inline)]

Hi Mathieu,

sorry, didn't have much time to play with Guix recently.
All I can say is that I haven't experienced the issue lately.
I'm on commit c03875b0361f114634caeb54935fe37a9b7b05af.

I'll try the commands you suggested later.  Thanks for your time!

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Message #23 received at 45302 <at> debbugs.gnu.org (full text, mbox):

From: Pierre Neidhardt <mail <at> ambrevar.xyz>
To: Mathieu Othacehe <othacehe <at> gnu.org>
Cc: 45302 <at> debbugs.gnu.org
Subject: Re: bug#45302: Avahi substitute discovery keeps trying to ping
 unaccessible servers
Date: Tue, 26 Jan 2021 11:53:27 +0100

[Message part 1 (text/plain, inline)]

Hi Mathieu,

> Glad you like it, and sorry for the late answer.

No worries! :)

>> substitute: guix substitute: warning: 10.0.0.5: connection failed: No route to host
>
> Once your laptop goes to sleep, Avahi should detect that the publish
> service is gone and remove it from the cache at
> /var/guix/discovery/publish.
>
> I'm having troubles reproducing it at home. Could you please run
> "avahi-browse -a" on your desktop, put your laptop to sleep, and check
> if the publish server disappears this way:
>
> --8<---------------cut here---------------start------------->8---
> - enp7s0f0 IPv6 guix-publish-cervin                           _guix_publish._tcp   local
> - enp7s0f0 IPv4 guix-publish-cervin                           _guix_publish._tcp   local
> --8<---------------cut here---------------end--------------->8---

To be sure we are on the same page, my desktop is the publisher, my
laptop is the client.

From my desktop:

--8<---------------cut here---------------start------------->8---
$ avahi-browse -a
+ enp7s0 IPv6 guix-publish-DESKTOP                                         _guix_publish._tcp   local
+ enp7s0 IPv4 guix-publish-DESKTOP                                         _guix_publish._tcp   local
+     lo IPv4 guix-publish-DESKTOP                                         _guix_publish._tcp   local
+ enp7s0 IPv6 LAPTOP                                                       _ssh._tcp            local
+ enp7s0 IPv6 DESKTOP                                                      _ssh._tcp            local
+ enp7s0 IPv4 LAPTOP                                                       _ssh._tcp            local
+ enp7s0 IPv4 DESKTOP                                                      _ssh._tcp            local
+     lo IPv4 DESKTOP                                                      _ssh._tcp            local
+ enp7s0 IPv6 LAPTOP [2a:81:b6:9b:6b:88]                                   _workstation._tcp    local
+ enp7s0 IPv6 DESKTOP [40:b0:76:0c:8d:47]                                  _workstation._tcp    local
+ enp7s0 IPv4 LAPTOP [2a:81:b6:9b:6b:88]                                   _workstation._tcp    local
+ enp7s0 IPv4 DESKTOP [40:b0:76:0c:8d:47]                                  _workstation._tcp    local
+     lo IPv4 DESKTOP [00:00:00:00:00:00]                                  _workstation._tcp    local
+ enp7s0 IPv6 LAPTOP                                                       _sftp-ssh._tcp       local
+ enp7s0 IPv6 DESKTOP                                                      _sftp-ssh._tcp       local
+ enp7s0 IPv4 LAPTOP                                                       _sftp-ssh._tcp       local
+ enp7s0 IPv4 DESKTOP                                                      _sftp-ssh._tcp       local
+     lo IPv4 DESKTOP                                                      _sftp-ssh._tcp       local
--8<---------------cut here---------------end--------------->8---

The output never changes, regardless of my laptop going to sleep or not.

You said "check if the publish server disappears" but why would it since it's
running on my desktop, which is not put to sleep?

Misunderstanding?  Forgive my ignorance about Avahi! :)

Cheers!

-- 
Pierre Neidhardt
https://ambrevar.xyz/

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