title: How does EC2 install the public key from your keypair?
body: <p>I am debugging creation of a custom AMI and it's not clear to me how EC2 actually installs the public key of your keypair onto your AMI... I presume it goes into ~someuser/.ssh/authorized_keys, but I cannot figure out if this is done exactly once, on every boot, or how the target user is determined.</p>