Add Docker secrets

[ahgraber]

Changes:

• Add docker/rootfs/etc/cont-init.d/01_s6-secret-init.sh to allow parsing of Docker secrets in s6 environment. (feature request: Does Project Support use of Docker Secrets? #818) and add stage2 logging if errors
• Change to ENTRYPOINT [ "/init" ]

This is up and running on dockerhub as ahgraber/nginx-proxy-manager if you'd like to test. The :test tag includes debug code to print the secret parsing to docker logs.

I'll also be sending a PR to allow mariadb-aria to also use docker secrets.

full compose stack (mariadb-aria and npm)

version: '3.7'

secrets:
  # secrets are single-line text files where the sole content is the secret
  DB_ROOT_PWD:
    file: .secrets/db_root_pwd.txt
  MYSQL_PWD:
    file: .secrets/mysql_pwd.txt

services:
  mariadb:
    image: ahgraber/mariadb-aria:latest
    container_name: mariadb
    secrets:
      - DB_ROOT_PWD
      - MYSQL_PWD
    environment:
      # MYSQL_ROOT_PASSWORD: "npm"  # use secret instead
      MYSQL_ROOT_PASSWORD__FILE: /run/secrets/DB_ROOT_PWD
      MYSQL_DATABASE: "npm"
      MYSQL_USER: "npm"
      # MYSQL_PASSWORD: "npm"  # use secret instead
      MYSQL_PASSWORD__FILE: /run/secrets/MYSQL_PWD 
    volumes:
      - ./data/mysql:/var/lib/mysql
    networks:
  npm:
    image: ahgraber/nginx-proxy-manager:latest
    container_name: npm
    secrets:
      - MYSQL_PWD
    environment:
      DISABLE_IPV6: 'true'
      DB_MYSQL_HOST: "mariadb"
      DB_MYSQL_PORT: 3306
      DB_MYSQL_USER: "npm"
      # DB_MYSQL_PASSWORD: "npm"  # use secret instead
      DB_MYSQL_PASSWORD__FILE: /run/secrets/MYSQL_PWD 
      DB_MYSQL_NAME: "npm"
    volumes:
      - ./data:/data
      - ./data/letsencrypt:/etc/letsencrypt
    ports:
      - 80:80
      - 443:443
      - 81:81
    depends_on:
      - mariadb

[jc21]

Docker Image for build 1 is available on DockerHub as jc21/nginx-proxy-manager:github-pr-872

[jc21]

Docker Image for build 2 is available on DockerHub as jc21/nginx-proxy-manager:github-pr-872

[jc21]

Docker Image for build 3 is available on DockerHub as jc21/nginx-proxy-manager:github-pr-872