Managing IP addresses and ports effectively

As your production configuration grows, it may become more difficult to manage a large number of IP addresses and ports.

As such, it is often helpful to have them defined in their own section.

In 07-security-ports.cfg, we have:

[buildout]
extends = 07-security-localhost.cfg

[hosts]
localhost = 127.0.0.1

[ports]
instance1 = 8081
instance2 = 8082

Notice that we are not using these definitions for anything yet. But we can use them like this:

${hosts:localhost}:${ports:instance1} 
${hosts:localhost}:${ports:instance2}

Effectively from now on, we have to change IP addresses and port numbers only in one place (assuming we change all static references such as 127.0.0.1:8080 to the new syntax).