[lvs-users] ldirectord - Real server maintenance discarded by check

Khosrow Ebrahimpour khosrow.ebrahimpour at ssc-spc.gc.ca
Thu Jan 16 20:55:36 GMT 2014


On 01/14/2014 06:26 AM, Jeremy Clerc wrote:
> Hello everyone,
>
> I have a question about ldirectord, we have a maintenance procedure where we set the real server weight to 0 so connections finish correctly, then we stop apache on the real server, sleep to let it close all its fcgi, then start the server, and finally put the weight back to 1.
>
> The problem is when we start the server, ldirectord makes his check, sees the server is up and so add it back with a weight of 1, 1s later it rereads its configuration and see that the server should have a weight of 0, so it changes the weight back to 0.
>
> During this short time period the server takes few thousands request and is not ready for it, it seems like a bug about the check system.
>
> ldirectord has been upgraded to the latest version available on github, also we have tested the "maintenacedir" configuration, which behaves the same way as described above.
>
> Here is the configuration:
>
> # Global Directives
> checktimeout=10
> checkinterval=5
> autoreload=yes
> logfile="/var/log/ldirectord.log"
> quiescent=yes
> fork=yes
> maintenancedir = /var/run/ldirectord_maintenance/
>
> virtual=....3:80
>          real=....72:80 gate
>          real=....73:80 gate
>          real=....74:80 gate
>          real=....75:80 gate
>          service=http
>          request="/fcgi-bin/envmy.fcgi"
>          receive="Mysql table test : OK"
>          scheduler=rr
>          protocol=tcp
>          checktype=negotiate
>
>
> Do you have any suggestion, any idea ? I have not found any bug related to this.
>
> Thank you all by advance,
>
> Regards,
>
> Jeremy
>
>
That seems like a bug in ldirectord. But without going through the 
ldirectord code to fix this issue, you could add one more step to your 
procedures:

1. set server weight to 0
2. stop apache2
** 3. create a file in 'maintenancedir' to remove the real server from 
the VIP

And to bring it back, you'd wait until your work is done before removing 
the maintenance file (as your last step).

The caveat here is that as far as I know, ldirectord does not 
differentiate between real servers across VIPs. So if you have the same 
real server in multiple VIPs, creating the maintenance file will remove 
it from all those VIPs.

Hope this helps,

-- 
Khosrow




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