Docker Compose: /mnt/sdb is always full – Magento

I’m working on a new docker-compose setup for Magento 2.4.2-p1.

I started to have issues with MySQL container running out of disk space.

There is a ton of space on my hard drive and on the Ubuntu (WSL2 on Windows 10).

Here is the output of MySQL container:

# df -h
Filesystem      Size  Used Avail Use% Mounted on
overlay         251G   23G  216G  10% /
tmpfs            64M     0   64M   0% /dev
tmpfs           7.9G     0  7.9G   0% /sys/fs/cgroup
shm             4.0G     0  4.0G   0% /dev/shm
/dev/sdd        251G   23G  216G  10% /etc/hosts
/dev/sdb        251G  238G  1.2G 100% /etc/mysql/conf.d/my.cnf
tmpfs           7.9G     0  7.9G   0% /proc/acpi
tmpfs           7.9G     0  7.9G   0% /sys/firmware

/mnt/sdb always full

So this must be something within Docker that is causing this. I noticed when I mount /var/www/php/ folder within docker-compose.yml to the mysql-74 container, it assigns it to /mnt/sdb. And every time /mnt/sdb is full!

mysql-74 container

Here is the output with the /var/www/php mounted on mysql-74 container:

# df -h
Filesystem      Size  Used Avail Use% Mounted on
overlay         251G   23G  216G  10% /
tmpfs            64M     0   64M   0% /dev
tmpfs           7.9G     0  7.9G   0% /sys/fs/cgroup
shm             4.0G     0  4.0G   0% /dev/shm
/dev/sdb        251G  238G  1.2G 100% /var/www/php
/dev/sdd        251G   23G  216G  10% /etc/hosts
tmpfs           7.9G     0  7.9G   0% /proc/acpi
tmpfs           7.9G     0  7.9G   0% /sys/firmware

php-74 container

If I look inside php-74 container there is a ton of space on it:

$ df -h
Filesystem      Size  Used Avail Use% Mounted on
overlay         251G   23G  216G  10% /
tmpfs            64M     0   64M   0% /dev
tmpfs           7.9G     0  7.9G   0% /sys/fs/cgroup
shm              64M     0   64M   0% /dev/shm
/dev/sdd        251G   23G  216G  10% /etc/hosts
tmpfs           7.9G     0  7.9G   0% /proc/acpi
tmpfs           7.9G     0  7.9G   0% /sys/firmware

Why is this happening? Is there another way to mount folder from another container? I just need it for ease of dumping / importing databases from my local folder.

docker-compose.yml

Here is my full docker-compose.yml file:

version: '3'

# Services
services:  
  # PHP Service
  php-74:
    build: ./.docker/php
    container_name: php-74
    #restart: always
    working_dir: /var/www/php
    environment:
      - COMPOSER_MEMORY_LIMIT=-1
    volumes:
      - ./src:/var/www/php
      - ./.ssh:/root/.ssh
    links:
      - mysql-74
      - redis-74
    depends_on:
      - mysql-74
    networks:
      - app-network-74

  # MySQL Service
  mysql-74:    
    shm_size: '4G'
    image: mysql:8.0.25
    container_name: mysql-74
    #restart: always
    environment:
      MYSQL_ROOT_PASSWORD: root
      MYSQL_DATABASE: magento
    volumes:
      - ./.docker/mysql/my.cnf:/etc/mysql/conf.d/my.cnf:ro
      #- mysqldata:/var/lib/mysqlmys
      #- ./assets:/var/www/php
      #- ./assets:/home/magento
    ports:
      - "3306:3306"
    networks:
      - app-network-74

  # PhpMyAdmin Service
  phpmyadmin-74:
    image: phpmyadmin/phpmyadmin:5-fpm
    container_name: phpmyadmin-74
    #restart: always
    environment:
      PMA_HOST: mysql-74
    volumes:
      - phpmyadmindata:/usr/src/phpmyadmin
    links:
      - mysql-74:db
    depends_on:
      - mysql-74
    networks:
      - app-network-74

  redis-74:
    image: redis:6
    #restart: always
    container_name: redis-74
    volumes:
      - redis-data:/data
    networks:
      - app-network-74

  # Nginx Service
  nginx-74:
    image: nginx:1.18
    container_name: nginx-74
    #restart: always
    ports:
      - 80:80
    volumes:
      - ./src:/var/www/php:ro
      - ./.docker/nginx/conf.d:/etc/nginx/conf.d:ro
      - phpmyadmindata:/usr/src/phpmyadmin
    depends_on:
      - php-74
      - phpmyadmin-74
    networks:
      - app-network-74

  elasticsearch-74:
    image: docker.elastic.co/elasticsearch/elasticsearch:7.9.3
    container_name: elasticsearch-74
    ports:
      - "9200:9200"
      - "9300:9300"
    networks:
      - app-network-74
    environment:
      - "discovery.type=single-node"
    

  rabbitmq-74:
    image: rabbitmq:3.8-management
    container_name: rabbitmq-74
    ports:
      - "15672:15672"
      - "5672:5672"
    volumes:
      - rabbitmqdata:/var/lib/rabbitmq
    networks:
        - app-network-74    

# Volumes
volumes:
  mysqldata:
  phpmyadmindata:
  redis-data:
    external: false
  elasticsearch:
  rabbitmqdata:

#Docker Networks
networks:
  app-network-74:
    driver: bridge

UPDATE:

Output of df on Ubuntu WSL2:

magento@PC:~/php74$ df -m
Filesystem     1M-blocks   Used Available Use% Mounted on
/dev/sdb          257007 242729      1155 100% /
tmpfs               8006    401      7606   6% /mnt/wsl
tools             976116 470182    505935  49% /init
none                8004      0      8004   0% /dev
none                8006      1      8006   1% /run
none                8006      0      8006   0% /run/lock
none                8006      0      8006   0% /run/shm
none                8006      0      8006   0% /run/user
tmpfs               8006      0      8006   0% /sys/fs/cgroup
C:               976116 470182    505935  49% /mnt/c
D:               476295   1535    474761   1% /mnt/d
/dev/sdd          257007  23347    220536  10% /mnt/wsl/docker-desktop-data/isocache
none                8006      1      8006   1% /mnt/wsl/docker-desktop/shared-sockets/host-services
/dev/sdc          257007    132    243752   1% /mnt/wsl/docker-desktop/docker-desktop-proxy
/dev/loop0           396    396         0 100% /mnt/wsl/docker-desktop/cli-tools

UPDATE:
Looks like I found the issue.

Magento 2.4.2-p1 has issues with CSP module dumping a lot of data into cache. Once you disable the CSP module the issue with cache overfilling (be it Redis or File cache) stops.

php bin/magento module:disable Magento_Csp