auto-upgrades and notify using email

modules/nixos/system/default.nix

@@ -15,6 +15,43 @@
     systemd.services.nix-gc.postStop =
       lib.mkIf (!config.server) "systemctl suspend";
 
+    # Update the system daily
+    system.autoUpgrade = {
+      enable = config.server; # Only auto upgrade servers
+      dates = "03:33";
+      flake = "git+${config.dotfilesRepo}";
+      randomizedDelaySec = "45min";
+      operation = "switch";
+      allowReboot = config.server; # Reboot servers
+      rebootWindow = {
+        lower = "00:01";
+        upper = "06:00";
+      };
+    };
+    systemd.services."notify-email@" =
+      let address = "system@${config.mail.server}";
+      in {
+        enable = config.mail.enable;
+        environment.SERVICE_ID = "%i";
+        script = ''
+          TEMPFILE=$(mktemp)
+          echo "From: ${address}" > $TEMPFILE
+          echo "To: ${address}" >> $TEMPFILE
+          echo "Subject: Failure in $SERVICE_ID" >> $TEMPFILE
+          echo -e "\nGot an error with $SERVICE_ID\n\n" >> $TEMPFILE
+          set +e
+          systemctl status $SERVICE_ID >> $TEMPFILE
+          set -e
+          ${pkgs.msmtp}/bin/msmtp \
+              --file=${config.homePath}/.config/msmtp/config \
+              --account=system \
+              ${address} < $TEMPFILE
+        '';
+      };
+    systemd.services.nixos-upgrade.onFailure =
+      lib.mkIf config.systemd.services."notify-email@".enable
+      [ "notify-email@%i.service" ];
+
   };
 
 }