Add support to retrieve a password from a file

[Sycri]

Would it be possible to retrieve the password of a database from a file instead of specifying it directly in an environment variable?

Example configuration in section databases:

databases:
  default:
    username: ${DB_USERNAME}
    passwordFile: ${DB_PASSWORD_FILE}
    url: localhost:1521/freepdb1

Example docker-compose.yaml:

secrets:
  database_password:
    file: ./secrets/database_password
services:
  exporter:
    image: container-registry.oracle.com/database/observability-exporter
    container_name: exporter
    command:
      - '--config.file=/exporter/config.yaml'
    ports:
      - 9161:9161
    environment:
      - DB_USERNAME=pdbadmin
      - DB_PASSWORD_FILE=/run/secrets/database_password
    secrets:
      - database_password
    volumes:
      - ./exporter:/exporter

In the configuration file passwordFile could be specified instead of password and the password itself would be served from a Docker secret.

[anders-swanson]

This seems reasonable & straighforward, don't mind adding this feature.