Question

How would you access a variable of the first host in a group?

Answer 1

Executes the following commands to access a variable of the first host in a group:

{{ hostvars[groups['webservers'][0]]['ansible_eth0']['ipv4']['address'] }}  

This command is accessing the hostname of the first machine in the webservers group. If you are doing this by a template, then use the jinja2 '#set', or you can use set_fact.