Re: Setting IPVS/LVS timeout in Keepalived

On Thu, Dec 12, 2013 at 07:14:47PM +0200, Ville Törhönen wrote:
> Hi,
> 
> 12.12.2013 16:54, Ryan O'Hara wrote:
> >On Thu, Dec 12, 2013 at 09:28:25AM -0500, Paul Robert Marino wrote:
> >>On Red Hat I would put that in /etc/sysconfig/keepalived even though
> >>thats a kludge as well its at least a little cleaner.
> >
> >Can you explain how this would work?
> 
> This would work as /etc/sysconfig/keepalived is executed in
> /etc/init.d/keepalived:
> 
> . /etc/sysconfig/keepalived

Right. That is what I suspected. For some reason I was concerned that
this was just expected to work. But the init script would have to be
made aware of these options and I am not entirely sure how systemd
deal with these sorts of things.

> This brings the user defined KEEPALIVED_OPTIONS variable to the init
> script. You could add commands to that file just as well, but it's
> still a kludge I think.
> 
> >>On Thu, Dec 12, 2013 at 6:25 AM, Ville Törhönen <[email protected]> wrote:
> >>>As expected, these modifications are not persistent and they are lost
> >>>after system restart. If the current LVS configuration is printed out
> >>>with 'ipsetadm-save -n', the timeout values aren't included. This makes
> >>>it impossible to reload the timeout values with the ipvsadm init script.
> >
> >Right, but as I am sure you know keepalived does not care about the
> >ipvsadm init script. We had this same issue in Piranha a while back
> >and I ended up adding the timeouts as options in the config file.
> 
> That's true, as they are just two different services. By default the
> ipvsadm init script loads the previous output of 'ipsetadm-save -n',
> and if it would include the TCP timeout values (set by 'ipvsadm
> --set') this problem could be solved by "starting" both ipvsadm and
> keepalived on appropriate run levels.

That is an interesting idea and it might just work as long as you
*only* save the ipvs timeouts.

> >>>This has been discussed several times in the lvs-users mailing list. It
> >>>has always come to a conclusion that LVS/IPVS is a framework and that
> >>>the management application should do the configuring. I know that there
> >>>are other ways to implement this, such as setting the timeout value in
> >>>/etc/rc.local, but it's obviously a nasty kludge.
> >
> >I'd be happy to add this to keepalived, but I'd like some ideas on
> >where these options would be place in the config file. The real_server
> >blocks and the primary means to configure ipvs related in keepalived,
> >but these timeouts are not set on a per real server basis. I'd suggest
> >we either add a new top-level config keyword or set them in
> >global_defs.
> >
> >Opinions?
> >
> >Ryan
> 
> Good to hear. Personally I think the best place would be
> global_defs, as this truly is a global definition. Keywords could be
> something like tcp_timeout, tcp_timeout_fin and udp_timeout. As you
> said, because of the LVS implementation it's not possible to add
> different timeouts per virtual server - although it would be very
> useful on some cases.

I tend to agree, but global_defs had nothing to do with ipvs. In other
words, you can run keepalived in vrrp-only mode in which case we'd
need to ignore any timeouts set in global_defs. Perhaps a new config
block like:

  ipvs_timeouts {
    tcp 900
    tcpfin 120
    udp 300
  }

Alexandre, do you have a preference?

Ryan

> Ville
> 
> >
> >
> >>>Thanks,
> >>>Ville
> >>>
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