Add arbi NixOS module

modules/arbi/default.nix

@@ -0,0 +1,22 @@
+{ config, pkgs, ... }:
+let
+  rev = "d531730d9640160f0519ef4b3640f8da49dd96f8";
+  arbi-flake = builtins.getFlake "git+ssh://git@github.com/aciceri/arbi.git?rev=${rev}";
+in
+{
+  imports = [ arbi-flake.nixosModules.arbi ];
+
+  services.arbi = {
+    enable = true;
+    log_level = "debug";
+    configFile = pkgs.writeText "arbi-config.kdl" ''
+      endpoint "wss://eth-mainnet.g.alchemy.com/v2/<REDACTED>"
+      pairs_file "pairs.json"
+      concurrency 4
+    '';
+  };
+
+  environment.persistence."/persist".directories = [
+    config.services.arbi.dataDir
+  ];
+}