Re: [pve-devel] [PATCH pve-network 1/1] frr: enable frr service on reloading the controller config

[Stefan Hanreich <s.hanreich@proxmox.com>]

> On 08.04.2025 21:42 CEST Stoiko Ivanov <s.ivanov@proxmox.com> wrote:
> 
>  
> On Tue, 8 Apr 2025 20:43:17 +0200
> Thomas Lamprecht <t.lamprecht@proxmox.com> wrote:
> 
> > On 08/04/2025 18:32, Stefan Hanreich wrote:
> > > Since we now ship frr with Proxmox VE, the frr service is available on
> > > the nodes but disabled on install. Prior to that users had to manually
> > > install frr, which automatically enabled the service. When applying a
> > > SDN configuration with an EVPN controller, we invoke systemctl restart
> > > frr, which leads to the service running but still being in the
> > > disabled state. This means that the EVPN setup is working until the
> > > next reboot. To avoid the situation where users configure an EVPN
> > > controller and everything seems to be working, until a restart breaks
> > > the EVPN setup, additionally enable the frr service before restarting
> > > it.
> > > 
> > > Signed-off-by: Stefan Hanreich <s.hanreich@proxmox.com>
> > > ---
> > >  src/PVE/Network/SDN/Controllers/EvpnPlugin.pm | 1 +
> > >  1 file changed, 1 insertion(+)
> > > 
> > > diff --git a/src/PVE/Network/SDN/Controllers/EvpnPlugin.pm b/src/PVE/Network/SDN/Controllers/EvpnPlugin.pm
> > > index c245ea2..4249cc5 100644
> > > --- a/src/PVE/Network/SDN/Controllers/EvpnPlugin.pm
> > > +++ b/src/PVE/Network/SDN/Controllers/EvpnPlugin.pm
> > > @@ -638,6 +638,7 @@ sub reload_controller {
> > >  	};
> > >  	if ($@) {
> > >  	    warn "frr reload command fail. Restarting frr.";
> > > +	    run_command(['systemctl', 'enable', 'frr']);  
> > 
> > can we guard this with an  file exists check for
> > "/etc/systemd/system/multi-user.target.wants/frr.service"? Not a must, but does
> > not feel right to unconditionally call systemctl enable.
> while talking off-list with Gabriel and Stefan I argued that `systemctl
> is-enabled` probably costs as much as running `systemctl enable` for a
> service (open socket - tell pid 1 to do stuff, wait for result) - so 
> now took the time to look into it (with strace, and ignoring what pid 1
> does) - in this case the output of `strace -yyttf systemctl enable frr`
> vs. `strace -yyttf systemctl is-enabled frr` is around 2.5 orders of
> magnitude (58k vs 9.9M) - and even for a service which does not ship an
> init-script anymore (thus causing a few forks for systemd-sysv-install),
> it's 56k vs 3.3M.
> 
> in any-case a `-e /etc/systemd/system/multi-user.target.wants/frr.service`
> is probably the most economic version.
> I tried figuring out if this check could break due to external
> cirumstances - if the service is started as part of a target and that
> target is pulled into multi-user.target - the symlink is not present
> (e.g. zfs-zed) - but even then we'd fall back to the "expensive" enabling.
> 
> summing up - the existence check seems sensible to me as well.

It certainly wouldn't hurt and your points sound sensible, I'll send
a v2 early tomorrow. Thanks for looking into this further!

> > 
> > >  	    eval { run_command(['systemctl', 'restart', 'frr']); };
> > >  	}
> > >      }  
> > 
> > 
> > 
> > _______________________________________________
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> > pve-devel@lists.proxmox.com
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> > 
> >


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