Support docker secrets for web password

[lightswitch05]

Support docker secrets for web password.

Description

This is the initial implementation for #556. I wanted to go ahead open a pull request to start discussions about the changes before I spent too much time with tests and documentation.

• If WEBPASSWORD is set, WEBPASSWORD_FILE is ignored.
• If WEBPASSWORD is empty, and WEBPASSWORD_FILE is set to a valid readable file path, then WEBPASSWORD will be set to the contents of WEBPASSWORD_FILE.

TODO:

• Discuss changes with pihole team
• Update documentation
• Add tests for WEBPASSWORD_FILE

Example using with Docker Secrets:

version: "3.3"
services:
  pihole:
    container_name: pihole
    image: pihole/pihole:latest
    network_mode: "host"
    environment:
      WEBPASSWORD_FILE: '/run/secrets/pihole_webpw'
    secrets:
      - pihole_webpw
    # Volumes store your data between container upgrades
    volumes:
      - './etc-pihole/:/etc/pihole/'
      - './etc-dnsmasq.d/:/etc/dnsmasq.d/'
    dns:
      - 127.0.0.1
      - 1.1.1.1

secrets:
  pihole_webpw:
    file: my_file_secret.txt

Motivation and Context

This implements request #556

How Has This Been Tested?

Manually tested at the moment. Need to add actual tests once there has been some discussions on the implementation.

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)

Checklist:

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.

[diginc]

Thanks, we'll get this build into the :dev image for more testing

[dschaper]

@lightswitch05 Can you send me your email at dan.schaper@pi-hole.net? We'd like to have you stop by our Mattermost server.

[pralor-bot]

This pull request has been mentioned on Pi-hole Userspace. There might be relevant details there:

https://discourse.pi-hole.net/t/v6-on-docker-ftlconf-webserver-api-password-support-secrets/76150/4