Docker Secrets

ℹ️ This feature is borrowed from mariadb docker image.

As an alternative to passing sensitive information via environment variables, _FILE may be appended to the below listed environment variables, causing the initialization script to load the values for those variables from files present in the container. In particular, this can be used to load passwords from Docker secrets stored in /run/secrets/<secret_name> files.

Supported are these variables:
APP_KEY, API_SECRET, CLOUDFLARE_API_KEY, DB_USERNAME, DB_PASSWORD, MAIL_USERNAME, MAIL_PASSWORD, MAILGUN_SECRET, S3_KEY, S3_SECRET