How to format the inventory file for amazon ec2 hosts?

[gigi...@gmail.com]

Hello,

I am unable to run the example ad hoc command:

ansible -m ping hosts --private-key=~/home/ec2-user/ -u ec2-user

the error is: [WARNING]: Could not match supplied host pattern, ignoring: hosts

The hostname is: ip-10-200-2-21.us-west-2.compute.internal
The host ip is: 10.200.2.21

I can ping the host from my ansible control node OS by this hostname.

I created the hosts file with the touch command and it looks like this:

ip-10-200-2-21.us-west-2.compute.internal

Do I need to include something more? Do I need to save it with a particular extension? Thank You much for any help.  

[gigi...@gmail.com]

the answer was to change hosts file to:

[ec2]
ip-10-200-2-21.us-west-2.compute.internal 

and change the command to:

ansible ec2 -m ping -i /etc/ansible/hosts