Mod cluster Concepts

TODO Deplete: https://home.feodorov.com:9443/wiki/Wiki.jsp?page=Mod_clusterConcepts

Internal

• mod_cluster
• mod_proxy Concepts

Overview

mod_cluster general idea is that the httpd process instantiates balancers, which are mechanism capable of sending requests into a set of back end nodes. Each balancer has a set of worker nodes, each worker node corresponding to a back end node. The node population associated with a balancer is dynamic - explain that. Virtual hosts work with balancers - they have the capability to either send requests into balancers, which in turn send the requests into their node population, or they resolve requests locally in their DocumentRoot.

Lifecycle of a Request

TODO

Balancer

TODO: what is a "balancer". There's a default one, whose default name is "mycluster". The name of the balancer can be specified by the back-end nodes. What is it? What is its function. Represent it on the diagram.

balancer://<balancer-name> is used in ProxyPass directives.

Places in which a balancer can be configured:

• mod_proxy_cluster CreateBalancer

Modules

mod_manager

mod_manager Configuration

mod_proxy_cluster

mod_proxy_cluster cannot work correctly if mod_proxy's mod_proxy_balancer is loaded, so mod_proxy_balancer must be removed from the httpd configuration.

mod_proxy_cluster Configuration

Dependency on mod_proxy

TODO

• Why are mod_proxy.so and mod_proxy_ajp.so and how are they used?
• Are there any mod_proxy modules that must be removed?