home/swaybar: add an indicator for systemd unit

Reports the number of systemd units (user and systems) that are in
failed state.

2 files changed, 38 insertions, 3 deletions

diff --git a/home/wm/waybar/default.nix b/home/wm/waybar/default.nix
index e712585..717d4c0 100644
--- a/home/wm/waybar/default.nix
+++ b/home/wm/waybar/default.nix
@@ -1,5 +1,12 @@
-{ config, lib, ... }:
-let isEnabled = config.my.home.wm.windowManager == "sway";
+{ config, lib, pkgs, ... }:
+let
+  isEnabled = config.my.home.wm.windowManager == "sway";
+  waybarSystemd =
+    pkgs.runCommandLocal "waybar-systemd"
+      { nativeBuildInputs = [ pkgs.makeWrapper ]; }
+      ''
+        makeWrapper ${./waybar-systemd.sh} $out/bin/waybar-systemd
+      '';
 in
 {
   config = lib.mkIf isEnabled {
@@ -9,13 +16,14 @@ in
 
       settings = [{
         layer = "bottom";
+        height = 25;
         position = "top";
         margin-top = 0;
         margin-left = 0;
         margin-right = 0;
         margin-bottom = 0;
         modules-left = [ "sway/workspaces" "sway/mode" ];
-        modules-right = [ "pulseaudio" "network" "battery" "clock" "tray" ];
+        modules-right = [ "custom/systemd" "pulseaudio" "network" "battery" "clock" "tray" ];
         "sway/workspaces" = { format = "{name}"; };
         "sway/mode" = { format = "{}"; };
         tray = { spacing = 10; };
@@ -29,6 +37,11 @@ in
           tooltip = true;
           tooltip-format = "{timeTo} ({capacity}%)";
         };
+        "custom/systemd" = {
+          exec = "${waybarSystemd}/bin/waybar-systemd";
+          return-type = "json";
+          interval = 10;
+        };
         pulseaudio = {
           format = "vol:{volume}%";
           format-bluetooth = "bt:{volume}%";
diff --git a/home/wm/waybar/waybar-systemd.sh b/home/wm/waybar/waybar-systemd.sh
new file mode 100755
index 0000000..bf4e8b8
--- /dev/null
+++ b/home/wm/waybar/waybar-systemd.sh
@@ -0,0 +1,22 @@
+#!/usr/bin/env bash
+
+failed_user="$(systemctl --plain --no-legend --user list-units --state=failed | awk '{ print $1 }')"
+failed_system="$(systemctl --plain --no-legend list-units --state=failed | awk '{ print $1 }')"
+
+failed_systemd_count="$(echo -n "$failed_system" | grep -c '^')"
+failed_user_count="$(echo -n "$failed_user" | grep -c '^')"
+
+text=$(( failed_systemd_count + failed_user_count ))
+
+if [ "$text" -eq 0 ]; then
+    printf '{"text": ""}\n'
+else
+    tooltip=""
+
+    [ -n "$failed_system" ] && tooltip="Failed system services:\n\n${failed_system}\n\n${tooltip}"
+    [ -n "$failed_user" ]   && tooltip="Failed user services:\n\n${failed_user}\n\n${tooltip}"
+
+    tooltip="$(printf  "%s" "$tooltip" | perl -pe 's/\n/\\n/g' | perl -pe 's/(?:\\n)+$//')"
+
+    printf '{"text": "%s", "tooltip": "%s" }\n' "$text" "$tooltip"
+fi