This commit adds an option to use the local SSH Agent to authenticate
connections to source instances started by the the EBS and Instance
Store builders.
This is of use when the source AMI _already_ has configuration for
authorized SSH keys - for example if one uses an SSH certificate
authority.
A further extension (not implemented in this commit) is to allow SSH
agent use with a pre-defined key pair, in order to allow keys with
passphrases to be used without giving the passphrase to Packer.
This adds support for using amazon-ebs/amazon-instance builder without
a keypair. If a ssh_private_key_file is supplied without a
ssh_keypair_name no temporary ssh keypair is created. If ssh_password is
used no temporary ssh keypair is created and the password is used when
trying to connect.
Closes#2301Closes#3156
The refactor of StepRegisterAmi to add the from_scratch parameter
incorrectly replaced iteration over image.BlockDeviceMappings with
iteration over the new mapping array when not using from_scratch. This
fixes the regression and renames the parameters to newMappings and
mappings for better clarity.