# Tests in: nixos/tests/ec2-image.nix

# This module defines a systemd service that sets the SSH host key and
# authorized client key and host name of virtual machines running on
# Amazon EC2, Eucalyptus and OpenStack Compute (Nova).

{
  config,
  lib,
  pkgs,
  ...
}:

with lib;

{
  imports = [
    (mkRemovedOptionModule [ "ec2" "metadata" ] "")
  ];

  config = {

    systemd.services.apply-ec2-data = {
      description = "Apply EC2 Data";

      wantedBy = [
        "multi-user.target"
        "sshd-keygen.service"
      ];
      before = [ "sshd-keygen.service" ];
      after = [ "fetch-ec2-metadata.service" ];

      path = [ pkgs.iproute2 ];

      script = ''
        ${optionalString (config.networking.hostName == "") ''
          echo "setting host name..."
          if [ -s /etc/ec2-metadata/hostname ]; then
              ${lib.getExe pkgs.hostname-debian} -F /etc/ec2-metadata/hostname
          fi
        ''}

        if ! [ -e /root/.ssh/authorized_keys ]; then
            echo "obtaining SSH key..."
            mkdir -p /root/.ssh
            chmod 0700 /root/.ssh
            if [ -s /etc/ec2-metadata/public-keys-0-openssh-key ]; then
                (umask 177; cat /etc/ec2-metadata/public-keys-0-openssh-key >> /root/.ssh/authorized_keys)
                echo "new key added to authorized_keys"
            fi
        fi

        # Extract the intended SSH host key for this machine from
        # the supplied user data, if available.  Otherwise sshd will
        # generate one normally.
        userData=/etc/ec2-metadata/user-data

        mkdir -p /etc/ssh
        chmod 0755 /etc/ssh

        if [ -s "$userData" ]; then
          key="$(sed 's/|/\n/g; s/SSH_HOST_DSA_KEY://; t; d' $userData)"
          key_pub="$(sed 's/SSH_HOST_DSA_KEY_PUB://; t; d' $userData)"
          if [ -n "$key" ] && [ -n "$key_pub" ] && [ ! -e /etc/ssh/ssh_host_dsa_key ]; then
              (umask 077; echo "$key" > /etc/ssh/ssh_host_dsa_key)
              echo "$key_pub" > /etc/ssh/ssh_host_dsa_key.pub
          fi

          key="$(sed 's/|/\n/g; s/SSH_HOST_ED25519_KEY://; t; d' $userData)"
          key_pub="$(sed 's/SSH_HOST_ED25519_KEY_PUB://; t; d' $userData)"
          if [ -n "$key" ] && [ -n "$key_pub" ] && [ ! -e /etc/ssh/ssh_host_ed25519_key ]; then
              (umask 077; echo "$key" > /etc/ssh/ssh_host_ed25519_key)
              echo "$key_pub" > /etc/ssh/ssh_host_ed25519_key.pub
          fi
        fi
      '';

      serviceConfig.Type = "oneshot";
      serviceConfig.RemainAfterExit = true;
    };

    systemd.services.print-host-key = {
      description = "Print SSH Host Key";
      wantedBy = [ "multi-user.target" ];
      after = [ "sshd-keygen.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.
        #
        # Format follows cloud-init conventions. The delimiters are based on:
        # - cloud-init write-ssh-key-fingerprints tool:
        #   https://github.com/canonical/cloud-init/blob/main/tools/write-ssh-key-fingerprints
        #
        # FINGERPRINTS section: for pre-26.05 tooling and human interactive consumption
        echo "-----BEGIN SSH HOST KEY FINGERPRINTS-----" > /dev/console
        for i in /etc/ssh/ssh_host_*_key.pub; do
            ${config.programs.ssh.package}/bin/ssh-keygen -l -f "$i" > /dev/console || true
        done
        echo "-----END SSH HOST KEY FINGERPRINTS-----" > /dev/console

        # KEYS section: full public keys for provisioning tools
        # Keys can be converted directly into SSH known_hosts files
        echo "-----BEGIN SSH HOST KEY KEYS-----" > /dev/console
        for i in /etc/ssh/ssh_host_*_key.pub; do
            cat "$i" > /dev/console
        done
        echo "-----END SSH HOST KEY KEYS-----" > /dev/console
      '';
      serviceConfig.Type = "oneshot";
      serviceConfig.RemainAfterExit = true;
    };

  };

  meta.maintainers = with maintainers; [ arianvp ];
}
