[sops] Move into proper module

nixos/modules/programs/sops/default.nix

@@ -0,0 +1,25 @@
+{ config, lib, pkgs, ... }:
+
+let
+  cfg = config.sisyphus.programs.sops;
+in {
+  options.sisyphus.programs.sops.enable = lib.mkEnableOption "Sops";
+
+  config = lib.mkIf cfg.enable {
+    environment.systemPackages = with pkgs; [
+      sops
+    ];
+
+    sops = {
+      # Add secrets.yml to the Nix Store.
+      defaultSopsFile = ../../../secrets/secrets.yaml;
+      age = {
+        # Automatically import SSH keys as age keys.
+        sshKeyPaths = [ "/etc/ssh/ssh_host_ed25519_key" ];
+        # Use an age key that is expected to already be in the filesystem.
+        # You will need to place this file manually.
+        keyFile = "/var/lib/sops-nix/key.txt";
+      };
+    };
+  };
+}