Nextcloud Docker Autoconfiguration bug example

bash steps to reproduce.sh

cp docker-compose-orig.yaml docker-compose.yaml
docker-compose up -d

# visit browser localhost:9090, it works

cp docker-compose-new.yaml docker-compose.yaml
docker-compose up -d  --remove-orphans
docker-compose restart

# visit browser localhost:9090, error 500
 
sudo cat containers/cloud/nextcloud/config/config.php | grep dbhost
# outputs   'dbhost' => 'db',
# should output:   'dbhost' => 'db2'


# try to fix it: install sudo
docker compose exec nextcloud bash -exc 'apt-get update -y && apt-get install sudo -y  '
docker compose exec nextcloud bash -exc 'sudo -u www-data php occ  config:system:set dbhost --value db2 '

# errors out with: Doctrine\DBAL\Exception: Failed to connect to the database: An exception occurred in the driver: SQLSTATE[HY000] [2002] php_network_getaddresses: getaddrinfo for db failed: Name or service not known in /var/www/html/lib/private/DB/Connection.php:140

docker-compose-new.yaml

version: '2'

services:

  nextcloud:
    container_name: nextcloud
    restart: unless-stopped
    image: nextcloud
    ports:
      - 9090:80
    volumes:
      - ./containers/cloud/nextcloud/apps:/var/www/html/apps
      - ./containers/cloud/nextcloud/config:/var/www/html/config
      - ./containers/cloud/nextcloud/data:/var/www/html/data
      - ./containers/cloud/nextcloud/themes:/var/www/html/themes
    depends_on:
      - db2
    environment:
      NEXTCLOUD_UPDATE: 1
      MYSQL_HOST: db2
      MYSQL_DATABASE: ncdb
      MYSQL_USER: nextcloud
      MYSQL_PASSWORD: nextcloud
      NEXTCLOUD_ADMIN_USER: nextcloud
      NEXTCLOUD_ADMIN_PASSWORD: nextcloud

  db2:
    container_name: maria-db
    restart: unless-stopped
    image: mariadb
    environment:
      MYSQL_ROOT_PASSWORD: root
      MYSQL_DATABASE: ncdb
      MYSQL_USER: nextcloud
      MYSQL_PASSWORD: nextcloud
    volumes:
      - ./containers/cloud/mariadb:/var/lib/mysql

docker-compose-orig.yaml

version: '2'

services:

  nextcloud:
    container_name: nextcloud
    restart: unless-stopped
    image: nextcloud
    ports:
      - 9090:80
    volumes:
      - ./containers/cloud/nextcloud/apps:/var/www/html/apps
      - ./containers/cloud/nextcloud/config:/var/www/html/config
      - ./containers/cloud/nextcloud/data:/var/www/html/data
      - ./containers/cloud/nextcloud/themes:/var/www/html/themes
    depends_on:
      - db
    environment:
      NEXTCLOUD_UPDATE: 1
      MYSQL_HOST: db
      MYSQL_DATABASE: ncdb
      MYSQL_USER: nextcloud
      MYSQL_PASSWORD: nextcloud
      NEXTCLOUD_ADMIN_USER: nextcloud
      NEXTCLOUD_ADMIN_PASSWORD: nextcloud

  db:
    container_name: maria-db
    restart: unless-stopped
    image: mariadb
    environment:
      MYSQL_ROOT_PASSWORD: root
      MYSQL_DATABASE: ncdb
      MYSQL_USER: nextcloud
      MYSQL_PASSWORD: nextcloud
    volumes:
      - ./containers/cloud/mariadb:/var/lib/mysql