# This module defines a systemd service that obtains the SSH key and # host name of virtual machines running on Amazon EC2, Eucalyptus and # OpenStack Compute (Nova). { config, lib, pkgs, ... }: with lib; { options = { ec2.metadata = mkOption { type = types.bool; default = false; description = '' Whether to allow access to EC2 metadata. ''; }; }; config = { systemd.services."fetch-ec2-data" = { description = "Fetch EC2 Data"; wantedBy = [ "multi-user.target" "sshd.service" ]; before = [ "sshd.service" ]; wants = [ "ip-up.target" ]; after = [ "ip-up.target" ]; path = [ pkgs.wget pkgs.iproute ]; script = '' ip route del blackhole 169.254.169.254/32 || true wget="wget -q --retry-connrefused -O -" echo "setting host name..." ${optionalString (config.networking.hostName == "") '' ${pkgs.nettools}/bin/hostname $($wget http://169.254.169.254/1.0/meta-data/hostname) ''} # Don't download the SSH key if it has already been injected # into the image (a Nova feature). if ! [ -e /root/.ssh/authorized_keys ]; then echo "obtaining SSH key..." mkdir -m 0700 -p /root/.ssh $wget http://169.254.169.254/1.0/meta-data/public-keys/0/openssh-key > /root/key.pub if [ $? -eq 0 -a -e /root/key.pub ]; then if ! grep -q -f /root/key.pub /root/.ssh/authorized_keys; then cat /root/key.pub >> /root/.ssh/authorized_keys echo "new key added to authorized_keys" fi chmod 600 /root/.ssh/authorized_keys rm -f /root/key.pub fi fi # Extract the intended SSH host key for this machine from # the supplied user data, if available. Otherwise sshd will # generate one normally. $wget http://169.254.169.254/2011-01-01/user-data > /root/user-data || true key="$(sed 's/|/\n/g; s/SSH_HOST_DSA_KEY://; t; d' /root/user-data)" key_pub="$(sed 's/SSH_HOST_DSA_KEY_PUB://; t; d' /root/user-data)" if [ -n "$key" -a -n "$key_pub" -a ! -e /etc/ssh/ssh_host_dsa_key ]; then mkdir -m 0755 -p /etc/ssh (umask 077; echo "$key" > /etc/ssh/ssh_host_dsa_key) echo "$key_pub" > /etc/ssh/ssh_host_dsa_key.pub fi ${optionalString (! config.ec2.metadata) '' # Since the user data is sensitive, prevent it from being # accessed from now on. ip route add blackhole 169.254.169.254/32 ''} ''; serviceConfig.Type = "oneshot"; serviceConfig.RemainAfterExit = true; }; systemd.services."print-host-key" = { description = "Print SSH Host Key"; wantedBy = [ "multi-user.target" ]; after = [ "sshd.service" ]; script = '' # Print the host public key on the console so that the user # can obtain it securely by parsing the output of # ec2-get-console-output. echo "-----BEGIN SSH HOST KEY FINGERPRINTS-----" > /dev/console ${pkgs.openssh}/bin/ssh-keygen -l -f /etc/ssh/ssh_host_dsa_key.pub > /dev/console echo "-----END SSH HOST KEY FINGERPRINTS-----" > /dev/console ''; serviceConfig.Type = "oneshot"; serviceConfig.RemainAfterExit = true; }; }; }