while spawning the fab file it asks me the login password for 'ubuntu'
Looks like there's an issue with your "ec2 key pairs". Make sure you have the correct key and that the permission of that key are 400.
To know if the key is working try to manually connect to the instance with
ssh -i ~/.ssh/<your-key> ubuntu@<your-host>
I wrote the default password of my ami i.e. 'ubuntu' but it didn't work. I even tried with my ssh key. I've browsed enough and nothing worked yet.Can anybody please help me out?
[] Executing task 'spawn'
Started...
Creating instance
EC2Connection:ec2.us-west-2.amazonaws.com
Instance state: pending
Instance state: pending
Instance state: pending
Instance state: pending
Instance state: running
Public dns: ec2-52-89-191-143.us-west-2.compute.amazonaws.com
Waiting 60 seconds for server to boot...
[ec2-52-89-191-143.us-west-2.compute.amazonaws.com] run: whoami
[ec2-52-89-191-143.us-west-2.compute.amazonaws.com] Login password for 'ubuntu':