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Hi all,
I'm currently setting up an LVS-NAT system with two directors and two
realservers. The realservers run a proprietary application which uses
apache (what I will call 'Port 80 apache'), tomcat and another apache
running on port 8008 with modperl (what I will call 'modperl apache'). The
application also uses an Oracle database on a separate server (unknown to
the directors). The realservers listen on port 80, and all traffic to/from
the realservers goes through this port.
When I install the proprietary software on a realserver, it doesn't
initially work; the only thing one sees when one hits it with a browser is
'proxy error'. This is because of these lines in the Port 80 apache
httpd.conf file:
RewriteRule ^/index.html http://%{HTTP_HOST}:8008/index.html [P]
RewriteRule ^/bin(.*).pl(.*) http://%{HTTP_HOST}:8008/bin$1.pl$2 [P]
RewriteRule ^/@@(.*) http://%{HTTP_HOST}:8008/@@$1 [P]
RewriteRule ^/%40%40(.*) http://%{HTTP_HOST}:8008/@@$1 [P]
What appears to be happening is that the client hits the VIP (on the active
director), and the director passes the hit through to the appropriate
realserver with, apparently, an HTTP Host: header of the VIP. Port 80
apache on the realserver sees this Host: header, and as a result, the
RewriteRules would appear to redirect the hit to port 8008 on the VIP
(which of course doesn't exist). Hence the proxy error.
To fix this, I've manually edited the httpd.conf file above and replaced
'%{HTTP_HOST}' with the actual FQDN of the realserver. However, I'm
wondering if this is but the tip of the proverbial iceberg; a 'grep -r'
through the application's files for 'HTTP_HOST' turns up quite a few
occurrences of it.
I'm assuming that, if my LVS director could rewrite the Host: header to be
the FQDN of the realserver to which it will send the hit, that would fix
this problem. Is this correct? If so, from a quick read of LVS doco,
mailing archives etc., it looks like I need a Layer 7 switch? If so, would
it be ktcpvs or something similar?
Please forgive my somewhat neonatal understanding of this issue - from a
couple of hours' reading this afternoon, my brain hurts ;-)
Thanks and Regards,
Guy.
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