Which load balancer supports Master/Slave configuration? - apache

Question

I am looking for load balancer for my web application that will support master-slave kind of configuration or algorithm support.
For now I am using apache proxy but with round robin LB method.
I am not sure if apache load balancer has master-slave support or any module?
Here is what I want exactly: Forward all request to one back end server and once the master server is down the slave or other server will act as hot stub.
Please suggest if any open source load balancer I can use w.r.t to my above requirement.

Answer 1

You can use nginx with its Upstream module.
Example configuration:
upstream myBackend {
server main.example.com:8080;
server back.example.com:8080 backup;
}
server {
location / {
proxy_pass http://myBackend;
}
}
While the first server (main.example.com) is up, nginx will use it. When it comes down, it will use the second server. You can read in the linked manual page for various other tuning parameters (for example when to mark server as failed). Nginx supports HTTPS for both incoming connections and also for connections to the proxy backend.
EDIT: For Apache it seems to be possible in version 2.4 using the Proxy Balancer. I have not tested this config. For more details see manual for ProxyPass.
ProxyPass "/" "balancer://hotcluster/"
<Proxy "balancer://hotcluster">
BalancerMember "http://1.2.3.4:8000"
# The server below is on hot standby
BalancerMember "http://1.2.3.6:8000" status=+H
</Proxy>