I found it. ![]()
Whitelisting is required. I have a packaged setup. It appears that the whitelist variable can only be used in configuration.yaml and not inside a package file.
For the record, my current setup is:
configuration.yaml
homeassistant:
packages: !include_dir_named packages
whitelist_external_dirs:
- /config
# etc.
packages/system.yaml
sensor:
- platform: filesize
file_paths:
- /config/home-assistant_v2.db