Hi Rainer,
Well, I did make some "bloody operation" by eliminating the VmWare
machine as the reverse proxy on my Mac. /Following Chris advise. :)/
Because apache2 on my Mac was not compiled with --enable-proxy, etc, I
downloaded the version 2.2.11 and compiled it with the three proxy
enablers /--enable-proxy, --enable-proxy-balancer, and --enable-proxy-
http/. I copied the reverse proxy config part and the JkMount
directives from the VmWare virtual machine into the httpd.conf file on
the Mac.
Now I have two machines:
- A PC with Windows 2000 and a Mac with OSX 10.5.6. The PC has
apache2 + mod_jk + tomcat (1 instance).
- A Mac that has apache2 + mod_jk + tomcat (3 instances). The Mac
also acts as a reverse proxy.
Fired up the newly compiled apache2 on the Mac and now everything
works like charm. It is failing over nicely when I stop the selected
tomcat node. I still have to test the fail over when I stop apache on
the PC in the middle of a session.
I changed two things:
1. moved the reverse proxy configuration off from the Windows Xp
inside the VmWare Fussion machine on the Mac, so the Mac itself became
the reverse proxy. Nothing was done to the tomcats or to the apache2
on the PC, not even stopping them.
2. On the Mac I installed a newer version of apache2. /2.2.11
compared to 2.2.9/
My guess is the VmWare update and the WinXp update on the virtual
machine from December changed somehow the security settings that did
not allow the information to flow back to the reverse proxy. Of
course, I am not sure about it. :) Theoretically it should have
worked without any problems. If I have time I will install a 2.2.11
apache2 on the XP and move back to it the reverse proxy configuration
from the Mac, to see if that helps or not.
Thanks ahead,
János
On Mar 25, 2009, at 6:49 PM, Rainer Jung wrote:
On 20.03.2009 18:48, János Löbb wrote:
Hi,
I have two real machines. One of them is a Windows XP running Apache
2.2.10 + mod_jk /release date of 10/30/2008/ + Tomcat 6.0.16. The
other
one is a Mac with OSX 10.5.6 with Apache 2.2.9 + mod_jk 1.2.26 and
Tomcat 6.0.16.
The XP machine runs one instance of Tomcat /node4/. The Mac runs 3, -
node1,2,3. Altogether 4 tomcats and they form a cluster.
...
In front of these two machines is an Apache 2.2.10 in a VMWare Fusion
virtual Machine on Windows XP in the Mac and configured as a
Reverse proxy
Here is the reverse proxy config from the httpd.conf
<snip>
ProxyRequests Off
<Proxy balancer://pathCluster>
BalancerMember http://bml0039.yalepath.org loadfactor=10
BalancerMember http://bml0073.yalepath.org loadfactor=10
ProxySet lbmethod=bytraffic
</Proxy>
ProxyPass /tc/ balancer://pathCluster/
ProxyPassReverse /tc/ balancer://pathCluster/
<Location /balancer-manager>
SetHandler balancer-manager
Order Deny,Allow
Allow from .yalepath.org
</Location>
</snip>
Here is the access_log from the reverse proxy:
<snip>
10.84.2.195 - - [20/Mar/2009:12:09:48 -0400] "GET /tc/CassetteLabeler
HTTP/1.1" 302 -
Returns with a trailing slash redirect
10.84.2.195 - - [20/Mar/2009:12:09:49 -0400] "GET /tc/
CassetteLabeler/
HTTP/1.1" 200 1506
Returns Content with 1506 Bytes
10.84.2.195 - - [20/Mar/2009:12:09:49 -0400] "GET
/CassetteLabeler/pathology.labeler.labeler.Labeler/Labeler.html
HTTP/1.1" 404 260
Wrong request, Prefix /tc/ missing. You need to find out, where this
request comes from. Likely it is either generated by someone using a
link in the page returned by the previous request, or that page
contains a meta tag in the head, which triggers a redirect to this
wrong URL.
So retrieve /tc/CassetteLabeler/ and have a look at the content to
identify, whether the wrong URL "/CassetteLabeler/
pathology.labeler.labeler.Labeler/Labeler.html" is in the page.
If no, we have to think further.
If yes, you have to ask, why is this wrong URL in there. The
question is, how your application generates this URL. If it
generates absolute URLs instead of relative ones, then you can
easily run into trouble, when the path of the real application is
different from the path used from the outside.
It is not unlikely though, that in such a case the app or the
framework used has a configurable path prefix. But first check, if
you can verify the wrong URL is somewhere in the content of the page.
The request from the reverse proxy did go to the XP machine:
Here are the log entries from the access log:
<snip>
10.84.2.195 - - [20/Mar/2009:12:09:49 -0400] "GET /CassetteLabeler
HTTP/1.1" 302 -
That's only the first request, answered with the trailing slash
redirect. The next request is the interesting one (the one answered
with status 200). It also has to appear somewhere in your 2nd laqyer
httpd logs.
Here are the entries from mod_jk.log of this XP machine:
<snip>
[Fri Mar 20 12:09:49.254 2009] [852:1808] [debug] jk_uri_worker_map.c
(682): Attempting to map URI '/CassetteLabeler' from 5 maps
Again that's the first request
[Fri Mar 20 12:09:49.551 2009] [852:1808] [debug] jk_ajp_common.c
(608):
status = 302
[Fri Mar 20 12:09:49.551 2009] [852:1808] [debug] jk_ajp_common.c
(615):
Number of headers is = 1
[Fri Mar 20 12:09:49.551 2009] [852:1808] [debug] jk_ajp_common.c
(671):
Header[0] [Location] = [http://bml0039.yalepath.org/CassetteLabeler/]
Aha, we get back a redirect (302) to localtion http://bml0039.yalepath.org/CassetteLabeler/
(which will be further rewritten by ProxyPassReverse). But that we
already know. The next request is the interesting one.
I have a production environment - just with 3 Macs and just one
tomcat
per machine forming a cluster - where a very similar configuration
runs
fine. The only difference is that the sticky parameters are NOT
with the
load balancer but with the real workers in the workers.properties
file,
This is very likely not the cause.
and the reverse proxy configuration somewhat different. Here it is:
<snip>
<IfModule mod_proxy_balancer.c>
ProxyPass /apps/ balancer://balancer-group/ stickysession=JSESSIONID
ProxyPassReverse /apps/ balancer://balancer-group/
<Proxy "balancer://balancer-group">
BalancerMember http://pathsrv1.yalepath.org loadfactor=10
BalancerMember http://raid2b.yalepath.org loadfactor=10
BalancerMember http://reptile.yalepath.org loadfactor=10
</Proxy>
</IfModule>
Looks pretty analogous at first sight.
Regards,
Rainer
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