Switched to watchtower env file after all

watchtower/docker-compose.yml

@@ -5,8 +5,8 @@ services:
         image: 'containrrr/watchtower'
         restart: 'always'
 
-        environment:
-            - 'WATCHTOWER_LABEL_ENABLE=true'
+        env_file:
+            - 'watchtower.env'
         labels:
             - 'com.centurylinklabs.watchtower.enable=true'
         volumes:

watchtower/watchtower.env.example

@@ -0,0 +1,5 @@
+# Check https://containrrr.dev/watchtower/arguments/
+# for full explanation of env vars
+
+TZ=
+WATCHTOWER_LABEL_ENABLE=true