nixpkgs/nixos/modules/virtualisation/ec2-data.nix
2015-06-30 17:25:56 +02:00

83 lines
3.1 KiB
Nix

# 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;
{
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 =
''
wget="wget -q --retry-connrefused -O -"
${optionalString (config.networking.hostName == "") ''
echo "setting host name..."
${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
'';
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
${config.programs.ssh.package}/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;
};
};
}