Just a vague suspicion..
What are the hostnames which you use in your workers.properties, for the
Tomcats ?
János Löbb wrote:
Hi Igor,
I use mod-proxy to balance the apaches/httpds. I use mod-jk t balance the
tomcats. For the tomcats f course I also have the workers.properties files in
the apache2/conf directory. When invoke the URL to the individual balance
members, everything works fine. It is when I try to use the reverse proxy then
every attempt to any of the tomcats creates a new session, so fail over does
not work.
Thanks,
János
On Mar 22, 2011, at 6:59 PM, Igor Cicimov wrote:
Interesting I had no idea you can mix mod_proxy and mod_jk, thought you
should use the one or the other. What I do I have workers.properties file in
the Apache conf directory with load-balancer worker that takes care of the
load balancing ans sticky sessions.
On Wed, Mar 23, 2011 at 8:54 AM, János Löbb <janos.l...@yale.edu> wrote:
Hi,
I have two machines bml0065.yalepath.org and bml0066.yalepath.org. Both
have OSX 10.6.6, apache 2.2.17 and mod_jk 1.2.31 installed. Tomcat is
7.0.10 on both.
Apache was compiled on both machines with proxy, proxy-balancer, proxy-http
and proxy-ajp enabled.
The bml0065 machine is configured as a reverse proxy.
The theory is, that users hit the bml0065 machine like
http://bml0065.yalepath.org/tc/examples/servlets/servlet/SessionExample
and using mod-proxy and mod-proxy-http it will select either bml0065 or
bml0066 depending on the lbmethod configured. Then let say it selects
bml0065. Then it comes to this machine as:
http://bml0065.yalepath.org/examples/servlets/servlet/SessionExample
From here, because there is a JkMount for examples in its httpd.conf, it
connects via mod_jk to the Tomcat instance on this machine, in this case
tomcat3.
The problem is that as soon the reverse proxy is involved new sessions are
created all the time, so session failover do not work. If I take the
reverse proxy out from the picture, everything works.
Here is the reverse proxy config from httpd.conf of the bml0065 machine
JkLogLevel info
JkMount /examples/* lb
JkMount /examples/servlets/servlet/* lb
JkMount /jkmanager/* jkstatus
JkWorkersFile "/usr/local/apache2/conf/workers.properties"
JkLogFile "/usr/local/apache2/logs/mod_jk.log
ProxyRequests Off
<Proxy balancer://pathCluster>
BalancerMember http://bml0065.yalepath.org loadfactor=10
route=tomcat3
BalancerMember http://bml0066.yalepath.org loadfactor=10
route=tomcat1
ProxySet lbmethod=bytraffic
</Proxy>
ProxyPass /tc/ balancer://pathCluster/
stickysession=JSESSIONID|jsessionid
ProxyPassReverse /tc/ balancer://pathCluster/
<Location /balancer-manager>
SetHandler balancer-manager
Order Deny,Allow
Allow from .yalepath.org
</Location>
A very similar setup worked in 2009 with Tomcat 6.0.18 and httpd 2.2.11.
Here are the snippets from both machine catalina.out file
<snip bml0065>
Mar 22, 2011 5:06:11 PM org.apache.catalina.core.ApplicationContext log
INFO: SessionListener:
sessionCreated('0409F29D221545DB0BB5F62205B24471.tomcat3')
Mar 22, 2011 5:06:11 PM org.apache.catalina.core.ApplicationContext log
INFO: SessionListener:
attributeAdded('0409F29D221545DB0BB5F62205B24471.tomcat3', 's1', 't3')
Mar 22, 2011 5:07:06 PM org.apache.catalina.core.ApplicationContext log
INFO: SessionListener:
sessionCreated('DE7A014A0F1659F0B777E0DF4A2355D4.tomcat3')
Mar 22, 2011 5:07:06 PM org.apache.catalina.core.ApplicationContext log
INFO: SessionListener:
attributeAdded('DE7A014A0F1659F0B777E0DF4A2355D4.tomcat3', 's2', 't3')
</snip>
<snip bml0066>
Mar 22, 2011 5:06:11 PM org.apache.catalina.core.ApplicationContext log
INFO: SessionListener:
sessionCreated('0409F29D221545DB0BB5F62205B24471.tomcat3')
Mar 22, 2011 5:06:11 PM org.apache.catalina.core.ApplicationContext log
INFO: SessionListener:
attributeAdded('0409F29D221545DB0BB5F62205B24471.tomcat3', 's1', 't3')
Mar 22, 2011 5:07:06 PM org.apache.catalina.core.ApplicationContext log
INFO: SessionListener:
sessionCreated('DE7A014A0F1659F0B777E0DF4A2355D4.tomcat3')
Mar 22, 2011 5:07:06 PM org.apache.catalina.core.ApplicationContext log
INFO: SessionListener:
attributeAdded('DE7A014A0F1659F0B777E0DF4A2355D4.tomcat3', 's2', 't3')
</snip>
Here is the last access session from the access_log:
<snip bml0065>
10.84.2.65 - - [22/Mar/2011:17:06:11 -0400] "POST
/examples/servlets/servlet/SessionExample HTTP/1.1" 200 1114
10.84.2.41 - - [22/Mar/2011:17:06:11 -0400] "POST
/tc/examples/servlets/servlet/SessionExample HTTP/1.1" 200 1114
10.84.2.65 - - [22/Mar/2011:17:06:11 -0400] "GET
/examples/servlets/images/code.gif HTTP/1.1" 304 -
10.84.2.41 - - [22/Mar/2011:17:06:11 -0400] "GET
/tc/examples/servlets/images/code.gif HTTP/1.1" 304 -
10.84.2.65 - - [22/Mar/2011:17:06:11 -0400] "GET
/examples/servlets/images/return.gif HTTP/1.1" 304 -
10.84.2.41 - - [22/Mar/2011:17:06:11 -0400] "GET
/tc/examples/servlets/images/return.gif HTTP/1.1" 304 -
::1 - - [22/Mar/2011:17:06:18 -0400] "OPTIONS * HTTP/1.0" 200 -
::1 - - [22/Mar/2011:17:06:19 -0400] "OPTIONS * HTTP/1.0" 200 -
10.84.2.65 - - [22/Mar/2011:17:07:06 -0400] "POST
/examples/servlets/servlet/SessionExample HTTP/1.1" 200 1114
10.84.2.41 - - [22/Mar/2011:17:07:06 -0400] "POST
/tc/examples/servlets/servlet/SessionExample HTTP/1.1" 200 1114
</snip>
The 10.84.2.41 is my machine. In the log above looks like the hit to the
reverse proxy - with the /tc/ start - inserted later than the converted url
for the given balance member.
There is nothing interesting in the apache error_log.
What am I doing wrong ?
This is a test cluster. The application developer wants to test his app's
failover by pulling the ethernet plug out from the non reverse proxy when
the session is on that machine.
Thanks ahead,
János
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