renaming hosts

I’m fairly new to ansible, so I’m still learning it. Please bare with me. I have a variable file that defines maps current hostnames of devices to new hostnames. I’m trying to write a playbook that will re the variable file and change the hostnames of the devices. So far I haven’t had any luck, can some one tell me where I’m going wrong with this?

The variable file and play book are pasted below

[joec@automation change_hostname]# cat hostname.yml