nixos-config/modules/system/services/crowdsec/default.nix

{
  config,
  inputs,
  pkgs,
  lib,
  ...
}:
let
  cfg = config.custom.services.crowdsec;

  user = config.users.users.crowdsec.name;
in
{
  imports = [ inputs.crowdsec.nixosModules.crowdsec ];

  options.custom.services.crowdsec = {
    enable = lib.mkEnableOption "";
    apiPort = lib.mkOption {
      type = lib.types.port;
      default = 8080;
    };
    prometheusPort = lib.mkOption {
      type = lib.types.port;
      default = 6060;
    };
    sources = {
      iptables = lib.mkEnableOption "";
      caddy = lib.mkEnableOption "";
      sshd = lib.mkEnableOption "";
    };
  };

  config = lib.mkIf cfg.enable {
    meta.ports.tcp.list = [
      cfg.apiPort
      cfg.prometheusPort
    ];

    sops.secrets."crowdsec/enrollment-key" = {
      owner = user;
      restartUnits = [ "crowdsec.service" ];
    };

    users.groups.caddy.members = lib.mkIf cfg.sources.caddy [ user ];

    services.crowdsec = {
      enable = true;
      package = inputs.crowdsec.packages.${pkgs.system}.crowdsec;
      enrollKeyFile = config.sops.secrets."crowdsec/enrollment-key".path;
      settings = {
        api.server.listen_uri = "localhost:${builtins.toString cfg.apiPort}";
        cscli.prometheus_uri = "http://localhost:${builtins.toString cfg.prometheusPort}";
        prometheus = {
          listen_addr = "localhost";
          listen_port = cfg.prometheusPort;
        };
      };

      allowLocalJournalAccess = true;
      acquisitions =
        let
          mkJournalAcquisition = unit: {
            source = "journalctl";
            journalctl_filter = [ "_SYSTEMD_UNIT=${unit}" ];
            labels.type = "syslog";
          };
        in
        [
          (lib.mkIf cfg.sources.iptables {
            source = "journalctl";
            journalctl_filter = [ "-k" ];
            labels.type = "syslog";
          })
          (lib.mkIf cfg.sources.caddy {
            filenames = [ "${config.services.caddy.logDir}/*.log" ];
            labels.type = "caddy";
          })
          (lib.mkIf cfg.sources.sshd (mkJournalAcquisition "sshd.service"))
        ];
    };

    systemd.services.crowdsec.serviceConfig.ExecStartPre =
      let
        installCollection = collection: ''
          if ! cscli collections list | grep -q "${collection}"; then
            cscli collections install ${collection}
          fi
        '';
        mkScript =
          name: text:
          lib.getExe (
            pkgs.writeShellApplication {
              inherit name text;
            }
          );
        collectionsScript =
          [
            (lib.singleton "crowdsecurity/linux")
            (lib.optional cfg.sources.iptables "crowdsecurity/iptables")
            (lib.optional cfg.sources.caddy "crowdsecurity/caddy")
            (lib.optional cfg.sources.sshd "crowdsecurity/sshd")
          ]
          |> lib.concatLists
          |> lib.map installCollection
          |> lib.concatLines
          |> mkScript "crowdsec-install-collections";
      in
      lib.mkAfter collectionsScript;

    custom.persist.directories = [ config.services.crowdsec.settings.config_paths.data_dir ];
  };
}