An example may COME up where we need to get the ipv4 address of an arbitrary interface, where the interface to be used may be supplied via a role PARAMETER or other input. Variable names can be built by adding strings together, like so:

{{ hostvars[inventory_hostname]['ansible_' + which_interface]['ipv4']['address'] }}

The TRICK about going through hostvars is necessary because it’s a dictionary of the entire namespace of variables. ‘inventory_hostname’ is a magic variable that indicates the current host you are looping over in the host LOOP.

An example may come up where we need to get the ipv4 address of an arbitrary interface, where the interface to be used may be supplied via a role parameter or other input. Variable names can be built by adding strings together, like so:

{{ hostvars[inventory_hostname]['ansible_' + which_interface]['ipv4']['address'] }}

The trick about going through hostvars is necessary because it’s a dictionary of the entire namespace of variables. ‘inventory_hostname’ is a magic variable that indicates the current host you are looping over in the host loop.