Add secret handling

nix/modules/nixos/secrets.nix

@@ -0,0 +1,21 @@
+{ inputs, config, ... }:
+
+{
+  imports = [
+    inputs.sops-nix.nixosModules.sops
+  ];
+
+  sops = {
+    defaultSopsFile = ../../secrets/secrets.yaml;
+    defaultSopsFormat = "yaml";
+
+    age = {
+      # This will automatically import the SSH keys as age keys
+      sshKeyPaths = [ "/etc/ssh/ssh_host_ed25519_key" ];
+      # This is where the age key for sops-nix is stored
+      keyFile = "/var/lib/sops-nix/key.txt";
+      # This will generate a new age key from the SSH key if it doesn't exist
+      generateKey = true;
+    };
+  };
+}