[FreeNX-kNX] ENABLE_LOAD_BALANCE_PREFERENCE option

[chris at ccburton.com]

freenx-knx-bounces at kde.org wrote on 04/09/2011 01:30:04:

> I have a system setup with four nodes being routed through a single 
> 'head' machine using load balancing.  Load balancing works fine 
> using round-robbin and random (I have yet to try to implement load 
> based),

Hmmm
To implement load-based load balancing, you have to

        cp nxcheckload.sample nxcheckload

on all the nx machines (and then edit them).

Set up ssh i.e. create user nxcal on all the nodes with
the same ~/.ssh/authorized_keys

Edit the nxcheckload on the load-balancer to use the
nxcal ssh keyfile, un-comment the ssh line then then comment
out the echo $RANDOM.

nxserver expects a larger value for lower utilization,
but I haven't really tested nxcheckload, so I couldn't say
how accurate it is.

Good luck if you try it . . .

> but it appears that the ENABLE_LOAD_BALANCE_PREFERENCE 
> directive does nothing.

Yup

> The client either connects to an existing 
> session or starts a new one with no sort of prompting the user.  I 
> have found absolutely no documentation on how to allow the user to 
> choose the server, so I may just be doing it wrong.

In theory . . 

ENABLE_LOAD_BALANCE_PREFERENCE=1
and
PREFERRED_HOST="yourpreferredhosthere"

should ignore load balancing and connect you to
"yourpreferredhosthere" provided that "yourpreferredhosthere"
is included somewhere in nxloadconfig/LOAD_BALANCE_SERVERS=

However PREFERRED_HOST is set from &host=yourpreferredhosthere
on the "start session" command line from the nxclient which
it tries to get from 

        SSH_ORIGINAL_COMMAND

which is never set anywhere in the code, see in the log entry

-- NX SERVER START: -c /usr/bin/nxserver - ORIG_COMMAND=

so nxserver reverts to what you have set in
LOAD_BALANCE_ALGORITHM to choose the host to which to
connect you.

Looks like this option wasn't ever completed.

You also need an nx client which sets host= for load
balancing which rules out nomachine's nxclient.

> 
> Also, the 4 nodes are setup as members of a NIS domain for 
> authentication.  The machine that is acting as the nx load-balancer 
> is also the NIS master, but does not authenticate through NIS (NIS 
> users cannot log into the machine).  This is an issue since nx 
> appears to be authenticating the user on the load-balancing server. 
> Is there a way to either hand off authentication to the nodes or 
> force nx to authenticate against ypserve instead of passwd/shadow 
> .... or is this more of an ssh problem.

You need to get ssh to hand off user/password authentication.

> 
> thanks,
> Matt
> 
> ----------------------------------------
> Matthew Beals
> Michigan Technological University
> Department of Atmospheric Sciences
> 1400 Townsend Drive
> B019a Fisher Hall
> Houghton, MI 49931
> mjbeals at mtu.edu
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