[lvs-users] R: How ldirectord polls real servers

Ivan Havlicek ivan at modulix.org
Thu Apr 25 16:15:17 BST 2013


There's always the ultime solution, create your own check (sometimes needed
for debugging purpose) :

    checktype=external
    checkport=443
    checkcommand="/usr/local/bin/check_mu_udp_server.sh"

which script may receive :
# $1 : IP virt
# $2 : Port virt
# $3 : IP real
# $4 : Port real
and just need to retun a value.

Hope usefull...


2013/4/24 Guglielmo Abbruzzese <g.abbruzzese at resi.it>

> In case of tcp protocol, in order to check the connection of a service of
> mine running on realserevrs  ("service=none") I already set " connect" as a
> checktype; so I assume this setting is the best choice even if such service
> should be configured for udp communication.
>
> Should such service be stopped for some reason, my hope is its node should
> be removed from the ldirector's realservers list
>
> Thank you all for your time
> Regards
> G.
>
> -----Messaggio originale-----
> Da: lvs-users-bounces at linuxvirtualserver.org
> [mailto:lvs-users-bounces at linuxvirtualserver.org] Per conto di Malcolm
> Turnbull
> Inviato: martedì 23 aprile 2013 18:26
> A: LinuxVirtualServer.org users mailing list.
> Oggetto: Re: [lvs-users] How ldirectord polls real servers
>
> Gugliemo,
>
> Ldirectord has various different health checking methods.
>
> For a simple TCP based service you could use the 'connect' check i.e.
> Can I do a TCP open on that port?
> For UDP you would probably just use a ping check as it is connectionless.
>
> The various methods are pretty well documented in the man page.
>
>
> On 23 April 2013 16:42, Guglielmo Abbruzzese <g.abbruzzese at resi.it> wrote:
> > Hi,
> > as far as you know where can I find a detailed
> > description/documentation about how ldirectord polls the realservers
> > in order to realize if the node should be actually removed from the
> cluster?
> >
> > For sure, " ldirectord monitors the health of the real servers by
> > periodically requesting a known URL and checking that the response
> > contains an expected response. If a real server fails then the server
> > is removed and will be reactivated once it comes back on line.".
> >
> > But what if the real servers implement a custom tcp or udp service?
> > In case of a tcp persistent connection, what if there is no data flow
> > for a while (shall I rely just on the 'persistent' timeout)?
> > And what about a cistom udp server?
> >
> > Is there a way to use tcpdump in order to detect such evidence?
> >
> > Thanks in advance for your advice,
> > Regards
> > G.
> >
> >
> >
> > _______________________________________________
> > Please read the documentation before posting - it's available at:
> > http://www.linuxvirtualserver.org/
> >
> > LinuxVirtualServer.org mailing list - lvs-users at LinuxVirtualServer.org
> > Send requests to lvs-users-request at LinuxVirtualServer.org
> > or go to http://lists.graemef.net/mailman/listinfo/lvs-users
>
>
>
> --
> Regards,
>
> Malcolm Turnbull.
>
> Loadbalancer.org Ltd.
> Phone: +44 (0)870 443 8779
> http://www.loadbalancer.org/
>
> _______________________________________________
> Please read the documentation before posting - it's available at:
> http://www.linuxvirtualserver.org/
>
> LinuxVirtualServer.org mailing list - lvs-users at LinuxVirtualServer.orgSend
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>
>
> _______________________________________________
> Please read the documentation before posting - it's available at:
> http://www.linuxvirtualserver.org/
>
> LinuxVirtualServer.org mailing list - lvs-users at LinuxVirtualServer.org
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>



-- 
                                                               Ivan

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