99 lines
3.5 KiB
Nix
99 lines
3.5 KiB
Nix
# This module defines a systemd service that obtains the SSH key and
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# host name of virtual machines running on Amazon EC2, Eucalyptus and
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# OpenStack Compute (Nova).
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{ config, pkgs, ... }:
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with pkgs.lib;
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{
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options = {
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ec2.metadata = mkOption {
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type = types.bool;
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default = false;
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description = ''
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Whether to allow access to EC2 metadata.
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'';
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};
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};
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config = {
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systemd.services."fetch-ec2-data" =
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{ description = "Fetch EC2 Data";
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wantedBy = [ "multi-user.target" ];
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before = [ "sshd.service" ];
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after = [ "network.target" ];
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path = [ pkgs.curl pkgs.iproute ];
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script =
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''
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ip route del blackhole 169.254.169.254/32 || true
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curl="curl --retry 3 --retry-delay 0 --fail"
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echo "setting host name..."
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${optionalString (config.networking.hostName == "") ''
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${pkgs.nettools}/bin/hostname $($curl http://169.254.169.254/1.0/meta-data/hostname)
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''}
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# Don't download the SSH key if it has already been injected
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# into the image (a Nova feature).
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if ! [ -e /root/.ssh/authorized_keys ]; then
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echo "obtaining SSH key..."
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mkdir -p /root/.ssh
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$curl -o /root/key.pub http://169.254.169.254/1.0/meta-data/public-keys/0/openssh-key
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if [ $? -eq 0 -a -e /root/key.pub ]; then
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if ! grep -q -f /root/key.pub /root/.ssh/authorized_keys; then
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cat /root/key.pub >> /root/.ssh/authorized_keys
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echo "new key added to authorized_keys"
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fi
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chmod 600 /root/.ssh/authorized_keys
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rm -f /root/key.pub
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fi
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fi
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# Extract the intended SSH host key for this machine from
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# the supplied user data, if available. Otherwise sshd will
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# generate one normally.
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$curl http://169.254.169.254/2011-01-01/user-data > /root/user-data || true
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key="$(sed 's/|/\n/g; s/SSH_HOST_DSA_KEY://; t; d' /root/user-data)"
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key_pub="$(sed 's/SSH_HOST_DSA_KEY_PUB://; t; d' /root/user-data)"
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if [ -n "$key" -a -n "$key_pub" -a ! -e /etc/ssh/ssh_host_dsa_key ]; then
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mkdir -m 0755 -p /etc/ssh
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(umask 077; echo "$key" > /etc/ssh/ssh_host_dsa_key)
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echo "$key_pub" > /etc/ssh/ssh_host_dsa_key.pub
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fi
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${optionalString (! config.ec2.metadata) ''
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# Since the user data is sensitive, prevent it from being
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# accessed from now on.
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ip route add blackhole 169.254.169.254/32
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''}
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'';
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serviceConfig.Type = "oneshot";
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serviceConfig.RemainAfterExit = true;
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};
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systemd.services."print-host-key" =
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{ description = "Print SSH Host Key";
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wantedBy = [ "multi-user.target" ];
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after = [ "sshd.service" ];
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script =
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''
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# Print the host public key on the console so that the user
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# can obtain it securely by parsing the output of
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# ec2-get-console-output.
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echo "-----BEGIN SSH HOST KEY FINGERPRINTS-----" > /dev/console
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${pkgs.openssh}/bin/ssh-keygen -l -f /etc/ssh/ssh_host_dsa_key.pub > /dev/console
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echo "-----END SSH HOST KEY FINGERPRINTS-----" > /dev/console
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'';
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serviceConfig.Type = "oneshot";
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serviceConfig.RemainAfterExit = true;
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};
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};
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}
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