add support for docker secrets (#8409)

* add support for docker secrets

* check for directory first

frigate/plus.py

@@ -3,6 +3,7 @@ import json
 import logging
 import os
 import re
+from pathlib import Path
 from typing import Any, List
 
 import cv2
@@ -36,6 +37,10 @@ class PlusApi:
         self.key = None
         if PLUS_ENV_VAR in os.environ:
             self.key = os.environ.get(PLUS_ENV_VAR)
+        elif os.path.isdir("/run/secrets") and PLUS_ENV_VAR in os.listdir(
+            "/run/secrets"
+        ):
+            self.key = Path(os.path.join("/run/secrets", PLUS_ENV_VAR)).read_text()
         # check for the addon options file
         elif os.path.isfile("/data/options.json"):
             with open("/data/options.json") as f: