Mod cluster Concepts
TODO Deplete: https://home.feodorov.com:9443/wiki/Wiki.jsp?page=Mod_clusterConcepts
Internal
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.
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:
Worker Node
Modules
mod_cluster_slotmem
mod_manager
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_advertise
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?