nixfiles/modules/restic/default.nix

{ config, lib, options, pkgs, ... }: let
  cfg = config.kyouma.restic;
in {
  options.kyouma.restic = let
    inherit (lib) mkOption types;
  in {
    inherit (options.services.restic.backups.type.getSubOptions [])
      timerConfig backupPrepareCommand backupCleanupCommand;
    enable = lib.mkEnableOption "Enable restic backup";
    paths = mkOption {
      description = "paths to backup";
      type = with types; listOf path;
      default = [];
    };
    pruneOpts = mkOption {
      description = "paths to backup";
      type = with types; listOf str;
      default = [
        "--keep-hourly 24"
        "--keep-daily 14"
        "--keep-weekly 8"
        "--keep-monthly 12"
      ];
    };
    remote = mkOption {
      description = "restic remote to use";
      type = types.nonEmptyStr;
      default = "zh3485.rsync.net";
    };
    remoteUser = mkOption {
      description = "remote ssh user";
      type = types.nonEmptyStr;
      default = "";
    };
    user = mkOption {
      description = "user who runs the backup job";
      type = types.nonEmptyStr;
      default = "root";
    };
    repo = mkOption {
      description = "restic repo";
      type = types.nonEmptyStr;
      default = "${config.networking.hostName}-backup";
    };
  };
  config = lib.mkIf cfg.enable {
    sops.secrets."restic/${cfg.remoteUser}/password" = {
      sopsFile = ../../secrets/restic/${cfg.remoteUser}.yaml;
    };
    sops.secrets."restic/${cfg.remoteUser}/id_ed25519" = {
      sopsFile = ../../secrets/restic/${cfg.remoteUser}.yaml;
    };

    services.restic.backups."${config.networking.hostName}-${cfg.remote}" = {
      inherit (cfg) paths user pruneOpts timerConfig backupPrepareCommand backupCleanupCommand;
      initialize = true;
      repository = "sftp:${cfg.remoteUser}@${cfg.remote}:${cfg.repo}";
      passwordFile = config.sops.secrets."restic/${cfg.remoteUser}/password".path;
      extraBackupArgs = [
        "--compression=max"
        "--pack-size=128"
        "--read-concurrency=8"
      ];
      extraOptions = let
        knownHost = pkgs.writeText "${cfg.remote}-known-host" (builtins.readFile ./${cfg.remote}/ssh_host_ed25519_key.pub);
        sshKey = config.sops.secrets."restic/${cfg.remoteUser}/id_ed25519".path;
      in [
        "sftp.command='ssh ${cfg.remoteUser}@${cfg.remote} -i ${sshKey} -o UserKnownHostsFile=${knownHost} -s sftp'"
      ];
    };
  }; 
}