jellyfin: alert on failure

services/jellyfin/jellyfin-failure-alert.nix

@@ -0,0 +1,65 @@
+{
+  config,
+  lib,
+  pkgs,
+  ...
+}:
+let
+  jfCfg = config.services.jellyfin;
+  ntfyCfg = config.services.ntfyAlerts;
+in
+lib.mkIf (jfCfg.enable && ntfyCfg.enable) {
+  systemd.services.jellyfin-failure-alert = {
+    description = "Monitor Jellyfin logs for client playback failures and alert via ntfy";
+    after = [
+      "network.target"
+      "jellyfin.service"
+    ];
+    wants = [ "jellyfin.service" ];
+    wantedBy = [ "multi-user.target" ];
+
+    serviceConfig = {
+      Type = "simple";
+      ExecStart = pkgs.writeShellScript "jellyfin-failure-alert-start" ''
+        set -euo pipefail
+        export NTFY_TOPIC=$(cat "$CREDENTIALS_DIRECTORY/ntfy-topic" | tr -d '[:space:]')
+        ${lib.optionalString (ntfyCfg.tokenFile != null) ''
+          export NTFY_TOKEN_FILE="$CREDENTIALS_DIRECTORY/ntfy-token"
+        ''}
+        exec ${pkgs.python3}/bin/python ${./jellyfin-failure-alert.py}
+      '';
+      Restart = "always";
+      RestartSec = "10s";
+
+      # Security hardening
+      DynamicUser = true;
+      NoNewPrivileges = true;
+      ProtectSystem = "strict";
+      ProtectHome = true;
+      ProtectKernelTunables = true;
+      ProtectKernelModules = true;
+      ProtectControlGroups = true;
+      MemoryDenyWriteExecute = true;
+      RestrictRealtime = true;
+      RestrictSUIDSGID = true;
+      RemoveIPC = true;
+
+      # DynamicUser needs jellyfin group to read 0700 log dir
+      SupplementaryGroups = [ jfCfg.group ];
+
+      # Load credentials from agenix secrets
+      LoadCredential = [
+        "ntfy-topic:${ntfyCfg.topicFile}"
+      ]
+      ++ lib.optional (ntfyCfg.tokenFile != null) "ntfy-token:${ntfyCfg.tokenFile}";
+    };
+
+    environment = {
+      JELLYFIN_LOG_DIR = "${jfCfg.dataDir}/log";
+      NTFY_SERVER_URL = ntfyCfg.serverUrl;
+      HOSTNAME = config.networking.hostName;
+      POLL_INTERVAL = "15";
+      DEDUP_WINDOW = "300";
+    };
+  };
+}