Apache Load Balancer

greyarea · 05-22-2014, 05:47 AM

Hello,

I am trying to set up a load balancer in Apache 2.2.15 in the follwing configuration:

Code:

                          |- Node1
Client <--> Balancer <--> |- Node2
                          |- Node3
                          |- Node4

My balancer configuration in the Virtual Host configuration file is like this:

Code:

#       ProxyRequests Off
#       <Proxy *>
#         Order Deny,Allow
#         Deny from all
#       </Proxy>

        ProxyPass / balancer://sitea/
        ProxyPassReverse / balancer://sitea/
        #ProxyPreserveHost On

        <Proxy balancer://sitea>
          BalancerMember http://aas-poc-sitea-node1.emcpoc.local:80
          BalancerMember http://aas-poc-sitea-node2.emcpoc.local:80
          BalancerMember http://aas-poc-sitea-node3.emcpoc.local:80
          BalancerMember http://aas-poc-sitea-node4.emcpoc.local:80
          ProxySet stickysession=BALANCERID
        </Proxy>

The problem I have is that the load balancer works but the balanced nodes (Node1-4) return a 301 Permanently Moved, the client browser then attempts to connect directly to the back-end node, which is not possible.

I understood that the ProxyPassReverse directive would prevent this. I have found that uncommenting the ProxyPreserveHost directive retains the correct URL but then the target page is not returned at all.

How can I force traffic to go through the balancer and prevent the client trying to follow the new URL in the 301 message?

Thanks,

sundialsvcs · 05-22-2014, 06:25 AM

Not sure, but do you know that all of the URLs listed in BalanceMember are correctly resolved?

greyarea · 05-23-2014, 04:35 AM

Quote:

do you know that all of the URLs listed in BalanceMember are correctly resolved?

Yes, they can be resolved by the balancer - confirmed on the console.

I have since been advised by the vendor that I should only be proxying/balancing requests to the /rest subdirectory. I have modified my configuration accordingly but am still having issues - modified config & log file below

Code:

        ProxyRequests Off

        ProxyPass /rest balancer://cluster/
        ProxyPassReverse /rest http://aas-poc-sitea-node1.emcpoc.local/rest
        ProxyPassReverse /rest http://aas-poc-sitea-node2.emcpoc.local/rest
        ProxyPassReverse /rest http://aas-poc-sitea-node3.emcpoc.local/rest
        ProxyPassReverse /rest http://aas-poc-sitea-node4.emcpoc.local/rest
        ProxyPreserveHost On

        <Proxy balancer://cluster>
          BalancerMember http://aas-poc-sitea-node1.emcpoc.local
          BalancerMember http://aas-poc-sitea-node2.emcpoc.local/rest
          BalancerMember http://aas-poc-sitea-node3.emcpoc.local/rest
          BalancerMember http://aas-poc-sitea-node4.emcpoc.local/rest
          ProxySet stickysession=BALANCERID
        </Proxy>

Code:

[Fri May 23 10:12:27 2014] [debug] mod_proxy_balancer.c(46): proxy: BALANCER: canonicalising URL //cluster/
[Fri May 23 10:12:27 2014] [debug] mod_proxy_balancer.c(280): proxy: BALANCER: Found value (null) for stickysession BALANCERID
[Fri May 23 10:12:27 2014] [debug] mod_proxy_balancer.c(1021): proxy: Entering byrequests for BALANCER (balancer://cluster)
[Fri May 23 10:12:27 2014] [debug] mod_proxy_balancer.c(1064): proxy: byrequests selected worker "http://aas-poc-sitea-node2.emcpoc.local" : busy 0 : lbstatus -1
[Fri May 23 10:12:27 2014] [debug] mod_proxy_balancer.c(581): proxy: BALANCER (balancer://cluster) worker (http://aas-poc-sitea-node2.emcpoc.local) rewritten to http://aas-poc-sitea-node2.emcpoc.local/
[Fri May 23 10:12:27 2014] [debug] mod_proxy.c(1020): Running scheme balancer handler (attempt 0)
[Fri May 23 10:12:27 2014] [debug] mod_proxy_http.c(1962): proxy: HTTP: serving URL http://aas-poc-sitea-node2.emcpoc.local/
[Fri May 23 10:12:27 2014] [debug] proxy_util.c(2026): proxy: HTTP: has acquired connection for (aas-poc-sitea-node2.emcpoc.local)
[Fri May 23 10:12:27 2014] [debug] proxy_util.c(2082): proxy: connecting http://aas-poc-sitea-node2.emcpoc.local/ to aas-poc-sitea-node2.emcpoc.local:80
[Fri May 23 10:12:27 2014] [debug] proxy_util.c(2209): proxy: connected / to aas-poc-sitea-node2.emcpoc.local:80
[Fri May 23 10:12:27 2014] [debug] proxy_util.c(2460): proxy: HTTP: fam 2 socket created to connect to aas-poc-sitea-node2.emcpoc.local
[Fri May 23 10:12:27 2014] [debug] proxy_util.c(2592): proxy: HTTP: connection complete to 172.16.117.32:80 (aas-poc-sitea-node2.emcpoc.local)
[Fri May 23 10:12:27 2014] [debug] mod_proxy_http.c(1732): proxy: start body send
[Fri May 23 10:12:27 2014] [debug] mod_proxy_http.c(1836): proxy: end body send
[Fri May 23 10:12:27 2014] [debug] proxy_util.c(2044): proxy: HTTP: has released connection for (aas-poc-sitea-node2.emcpoc.local)
[Fri May 23 10:12:27 2014] [debug] mod_proxy_balancer.c(622): proxy_balancer_post_request for (balancer://cluster)