Special host management using patterns

We have already established that you will often want to run either an ad hoc command or a playbook against only a subsection of your inventory. So far, we have been quite precise in doing that, but let’s now expand upon this by looking at how Ansible can work with patterns to figure out which hosts a command (or playbook) should be run against.

As a starting point, let’s again consider an inventory that we defined earlier in this chapter for the purposes of exploring host groups and child groups. For your convenience, the inventory contents are provided again here:

loadbalancer.example.org
[frontends]
web01.example.org
web02.example.org
[apps]
app01.example.org
app02.example.org
[databases]
db01.example.org
db02.example.org
[fedora:children]
apps
databases
[ubuntu:children]
frontends

To demonstrate host/group selection by pattern, we shall use the --list-hosts switch with the ansible command to see which hosts Ansible would...