GitHub PKI

github_pki is a command that can be used to retrieve and dump SSH keys from GitHub.

$ github_pki -a /home/bob/.ssh/authorized_keys \
             -o "zeorg" -T "devops" \
             -t 398d6d326b546d70f9e1ef91abad1fc5ee0f1f39

$ github_pki -s /etc/software/ssl \
             -u bob -u alice \
             -t 398d6d326b546d70f9e1ef91abad1fc5ee0f1f39

github_pki can be used directly in sshd_config to be called dynamically whenever an SSH session is started.

First, make sure github_pki is installed in a directory only writable by root:

$ make
$ sudo cp github_pki /usr/local/bin/

Next, configure your sshd_config, outputing the keys to stdout:

AuthorizedKeysCommand /usr/local/bin/github_pki -t 398d6d326b546d70f9e1ef91abad1fc5ee0f1f39 -u bob -u alice -a -
AuthorizedKeysCommandUser github_pki

Make sure the chosen user exists, and use the properly generated GitHub token.

Finally, restarted ssh (e.g. on Ubuntu):

$ sudo service ssh restart

You should now be able to login to any user on the machine using one of the GitHub keys specified in the command.

$ docker run -v $PWD/authorized_keys:/authorized_keys \
             -e GITHUB_TOKEN=398d6d326b546d70f9e1ef91abad1fc5ee0f1f39 \
             camptocamp/github_pki -u bob -u alice=jessie \
                -a /authorized_keys

Individual users (-u or GITHUB_USERS) can be passed in the following format:

$ github_pki -u bob -u alice

GitHub user bob is called alice locally:

$ github_pki -u bob=alice

$ github_pki -u bob:1234