nixpkgs/modules/virtualisation/ec2-data.nix

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# This module defines an Upstart job that obtains the SSH key and host
# name of virtual machines running on Amazon EC2, Eucalyptus and
# OpenStack Compute (Nova).
{ config, pkgs, ... }:
{
jobs.fetchEC2Data =
{ name = "fetch-ec2-data";
startOn = "ip-up";
task = true;
script =
''
echo "setting host name..."
${pkgs.nettools}/bin/hostname $(${pkgs.curl}/bin/curl 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 -p /root/.ssh
${pkgs.curl}/bin/curl --retry 3 --retry-delay 0 --fail \
-o /root/key.pub \
http://169.254.169.254/1.0/meta-data/public-keys/0/openssh-key
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
# 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
'';
};
}