Add and enable flakes as default.

Add Redis/Valkey database to database.nix

nix-system-configs/modules/lix-default.nix

@@ -109,5 +109,5 @@
   ];
 
   # Enable experimental features for nix command and flakes
-  nix.settings.experimental-features = [ "nix-command" "flakes" ];
+  nix.settings.experimental-features = ["nix-command" "flakes"];
 }

nix-system-configs/modules/system/database.nix

@@ -59,10 +59,12 @@ in {
     networking.firewall.allowedTCPPorts = [
       5432 # PostgreSQL
       3306 # MariaDB/MySQL
+      6379 # Valkey
     ];
     networking.firewall.allowedUDPPorts = [
       5432 # PostgreSQL
       3306 # MariaDB/MySQL
+      6379 # Valkey
     ];
 
     # Bootloader.
@@ -111,6 +113,48 @@ in {
       python3Packages.wheel
       python3Packages.cryptography
       google-cloud-sdk
+
+      # Valkey (as Redis alternative)
+      valkey
+    ];
+
+    # Systemd service for Valkey (port 6379). Creates config and directories via Nix-managed units.
+    systemd.services.valkey_6379 = {
+      description = "Valkey in-memory store (port 6379)";
+      wants = ["network.target"];
+      after = ["network.target"];
+      wantedBy = ["multi-user.target"];
+      serviceConfig = {
+        ExecStart = "${pkgs.valkey}/bin/valkey-server /etc/valkey/6379.conf";
+        Restart = "always";
+        User = "root";
+        RuntimeDirectory = "valkey_6379"; # places runtime dir under /run
+        # Keep logs in a file (configured below) but also keep unit re-start behavior
+      };
+      # Ensure the service is started at boot
+      wantedBy = ["multi-user.target"];
+    };
+
+    # Provide the Valkey config file at /etc/valkey/6379.conf
+    environment.etc = lib.mkOverride 0 (lib.attrsets.union environment.etc {
+      "valkey/6379.conf" = {
+        text = ''
+          # Valkey configuration managed by NixOS
+          daemonize yes
+          pidfile /var/run/valkey_6379.pid
+          port 6379
+          loglevel notice
+          logfile /var/log/valkey_6379.log
+          dir /var/valkey/6379
+        '';
+      };
+    });
+
+    # Create data and log directories using systemd tmpfiles rules so paths exist on boot
+    systemd.tmpfiles.rules = lib.mkForce [
+      "d /var/valkey 0755 root root - -"
+      "d /var/valkey/6379 0755 root root - -"
+      "f /var/log/valkey_6379.log 0644 root root - -"
     ];
 
     system.stateVersion = "25.11";