DANBOORU_API_KEY - your gold account danbooru API key
DANBOORU_LOGIN - your danbooru login
DOKKU_LETSENCRYPT_EMAIL - your let's encrypt email
TG_TOKEN - your bot token
You should restart app with dokku ps:restart <YOUR_APP> every day to rebuild cache (don't worry, bot will be up during restart, new container will replace old after building cache)
You could post into TG_CHAT channel with docker exec <YOUR_APP>.web.1 /app/sigusr1.sh