Lost aws public key?

gistfile1.txt

Just do this: https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/ec2-key-pairs.html#replacing-lost-key-pair

Here is what I did, thanks to Eric Hammond's blog post:

Stop the running EC2 instance
Detach its /dev/xvda1 volume (let's call it volume A) - see here
Start new t1.micro EC2 instance, using my new key pair. Make sure you create it in the same subnet, otherwise you will have to terminate the instance and create it again. - see here
Attach volume A to the new micro instance, as /dev/xvdf (or /dev/sdf)
SSH to the new micro instance and mount volume A to /mnt/tmp

$ sudo mount /dev/xvdf1 /mnt/tmp

Copy ~/.ssh/authorized_keys to /mnt/tmp/home/ubuntu/.ssh/authorized_keys

Logout
Terminate micro instance
Detach volume A from it
Attach volume A back to the main instance as /dev/xvda
Start the main instance
Login as before, using your new .pem file
That's it.