ntfy

modules/nixos/power/default.nix

@@ -1,13 +1,96 @@
 {
   config,
   lib,
+  pkgs,
   namespace,
   ...
 }:
 with lib;
 let
-  inherit (lib.${namespace}) mkOpt;
+  inherit (lib.${namespace}) mkOpt mkBoolOpt;
   cfg = config.${namespace}.power.ups;
+
+  # Script called by upsmon for every UPS event.  Reads NTFY_USER and
+  # NTFY_PASSWORD from the environment (injected via EnvironmentFile on the
+  # upsmon systemd service).  upsmon passes the event type as the first
+  # argument (e.g. ONBATT, ONLINE, LOWBATT, FSD, COMMOK, COMMBAD, etc).
+  upsNotifyScript = pkgs.writeShellScript "ups-ntfy-notify" ''
+    EVENT="$1"
+    HOST="$(${pkgs.hostname}/bin/hostname)"
+    SERVER="https://ntfy.mjallen.dev"
+    TOPIC="ups"
+
+    case "$EVENT" in
+      ONBATT)
+        TITLE="UPS on battery: $HOST"
+        PRIORITY="high"
+        TAGS="battery,rotating_light"
+        MESSAGE="Power failure detected. UPS is now running on battery."
+        ;;
+      ONLINE)
+        TITLE="UPS back on mains: $HOST"
+        PRIORITY="low"
+        TAGS="electric_plug,white_check_mark"
+        MESSAGE="Power restored. UPS is back on mains power."
+        ;;
+      LOWBATT)
+        TITLE="UPS battery LOW: $HOST"
+        PRIORITY="urgent"
+        TAGS="battery,sos"
+        MESSAGE="UPS battery is critically low. Shutdown imminent."
+        ;;
+      FSD)
+        TITLE="UPS forced shutdown: $HOST"
+        PRIORITY="urgent"
+        TAGS="warning,sos"
+        MESSAGE="Forced shutdown initiated by UPS."
+        ;;
+      COMMOK)
+        TITLE="UPS comms restored: $HOST"
+        PRIORITY="low"
+        TAGS="electric_plug,white_check_mark"
+        MESSAGE="Communication with UPS restored."
+        ;;
+      COMMBAD)
+        TITLE="UPS comms lost: $HOST"
+        PRIORITY="high"
+        TAGS="warning,rotating_light"
+        MESSAGE="Lost communication with UPS."
+        ;;
+      SHUTDOWN)
+        TITLE="UPS shutdown in progress: $HOST"
+        PRIORITY="urgent"
+        TAGS="warning,sos"
+        MESSAGE="System is shutting down due to UPS condition."
+        ;;
+      REPLBATT)
+        TITLE="UPS battery needs replacement: $HOST"
+        PRIORITY="default"
+        TAGS="battery,warning"
+        MESSAGE="UPS reports battery needs replacement."
+        ;;
+      NOCOMM)
+        TITLE="UPS unreachable: $HOST"
+        PRIORITY="high"
+        TAGS="warning,rotating_light"
+        MESSAGE="UPS is not reachable."
+        ;;
+      *)
+        TITLE="UPS event on $HOST: $EVENT"
+        PRIORITY="default"
+        TAGS="electric_plug"
+        MESSAGE="UPS event: $EVENT"
+        ;;
+    esac
+
+    ${pkgs.curl}/bin/curl -sf \
+      --user "$NTFY_USER:$NTFY_PASSWORD" \
+      -H "Title: $TITLE" \
+      -H "Priority: $PRIORITY" \
+      -H "Tags: $TAGS" \
+      -d "$MESSAGE" \
+      "$SERVER/$TOPIC" || true
+  '';
 in
 {
   options.${namespace}.power.ups = {
@@ -17,6 +100,11 @@ in
     upsUser = mkOpt types.str "nas-admin" "Name of the ups user";
 
     upsdPort = mkOpt types.int 3493 "Port for upsd";
+
+    ntfy = {
+      enable = mkBoolOpt false "Send ntfy notifications on UPS events";
+      envFile = mkOpt types.str "" "Path to env file containing NTFY_USER and NTFY_PASSWORD";
+    };
   };
 
   config = mkIf cfg.enable {
@@ -61,6 +149,49 @@ in
           passwordFile = config.sops.secrets."jallen-nas/ups_password".path;
           user = cfg.upsUser;
         };
+
+        # Call the notify script for all event types we care about.
+        settings = mkIf cfg.ntfy.enable {
+          NOTIFYCMD = "${upsNotifyScript}";
+          NOTIFYFLAG = [
+            [
+              "ONLINE"
+              "SYSLOG+WALL+EXEC"
+            ]
+            [
+              "ONBATT"
+              "SYSLOG+WALL+EXEC"
+            ]
+            [
+              "LOWBATT"
+              "SYSLOG+WALL+EXEC"
+            ]
+            [
+              "FSD"
+              "SYSLOG+WALL+EXEC"
+            ]
+            [
+              "COMMOK"
+              "SYSLOG+WALL+EXEC"
+            ]
+            [
+              "COMMBAD"
+              "SYSLOG+WALL+EXEC"
+            ]
+            [
+              "SHUTDOWN"
+              "SYSLOG+WALL+EXEC"
+            ]
+            [
+              "REPLBATT"
+              "SYSLOG+WALL+EXEC"
+            ]
+            [
+              "NOCOMM"
+              "SYSLOG+WALL+EXEC"
+            ]
+          ];
+        };
       };
 
       upsd = {
@@ -74,5 +205,8 @@ in
       };
     };
 
+    # Inject ntfy credentials into the upsmon service so the notify script
+    # can read NTFY_USER and NTFY_PASSWORD from the environment.
+    systemd.services.upsmon.serviceConfig.EnvironmentFile = mkIf cfg.ntfy.enable [ cfg.ntfy.envFile ];
   };
 }