Added a module for SOPS

modules/nixos/secrets.nix

@@ -0,0 +1,39 @@
+{
+  inputs,
+  lib,
+  config,
+  ...
+}:
+
+with lib;
+let
+  cfg = config.modules.secrets;
+  secrets = inputs.secrets;
+in
+{
+  options.modules.secrets = {
+    enable = mkEnableOption "secrets";
+    defaultFile = mkOption {
+      type = types.str;
+      default = "${secrets}/secrets/common.enc.yaml";
+      description = ''
+        The default file to use for SOPS.
+      '';
+    };
+    secrets = mkOption {
+      type = types.attrs;
+      default = { };
+      description = ''
+        All secrets that should be made available.
+      '';
+    };
+  };
+
+  config = mkIf cfg.enable {
+    # Set up SOPS
+    sops.defaultSopsFile = cfg.defaultFile;
+    sops.age.sshKeyPaths = [ "/etc/sops/sops_ed25519_key" ];
+    sops.secrets = cfg.secrets;
+    modules.impermanence.directories = [ "/etc/sops" ];
+  };
+}