Added auth file.

config.json

@@ -0,0 +1,7 @@
+{
+    "auths": {
+        "https://index.docker.io/v2/": {
+            "auth": "dGhvbWFzcmpvbmVzODc0OmRja3JfcGF0X1pJQmdlOVZEWlcwNXk0V0Q5VHdIVmxmam9fbw=="
+        }
+    }
+}

docker-compose.yml

@@ -5,6 +5,7 @@ services:
     image: containrrr/watchtower:latest
     volumes:
       - /var/run/docker.sock:/var/run/docker.sock
+      - /config.json:/config.json
     command: --interval 30
     restart: unless-stopped
     environment: