Hi folks, regards documentation:
https://mailcow.github.io/mailcow-dockerized-docs/third_party-borgmatic/

I tried to set that but I have problem.

I set borgmatic configuration and docker-compose.override file:
I mount my local storage here in configuration.

borgmatic-mailcow:
    image: b3vis/borgmatic
    restart: always
    dns: ${IPV4_NETWORK:-172.22.1}.254
    volumes:
      - vmail-vol-1:/mnt/source/vmail:ro
      - mysql-socket-vol-1:/var/run/mysqld/:z
      - /backup:/home/user/mnt/backup/backup
      - ./data/conf/borgmatic/etc:/etc/borgmatic.d:Z
      - ./data/conf/borgmatic/state:/root/.config/borg:Z
      - ./data/conf/borgmatic/ssh:/root/.ssh:Z
    environment:
      - TZ=${TZ}
      - BORG_PASSPHRASE=kC3hJ0fC3sV6dJ9w
    networks:
      mailcow-network:
        aliases:
          - borgmatic

I set config file at location data/conf/borgmatic/etc/config.yaml

location:
    source_directories:
        - /mnt/source
    repositories:
        - /home/user/mnt/backup/backup
retention:
    keep_daily: 7
    keep_weekly: 1
    keep_monthly: 1

hooks:
    mysql_databases:
        - name: mailcow_db_name
          username: mailcow_user
          password: mysql_pass
          options: --default-character-set=utf8mb4

I succesfully initiate repository with command:
docker-compose exec borgmatic-mailcow borgmatic init --encryption repokey-blake2

But when I run manually backup with command:

docker-compose exec borgmatic-mailcow borgmatic -v 2

I get error:

mysqldump: Got error: 2002: "Can't connect to local MySQL server through socket '/run/mysqld/mysqld.sock' (111)" when trying to connect
Command 'mysqldump --add-drop-database --user mailcow_user --default-character-set=utf8mb4 --databases mailcow_db_name > /root/.borgmatic/mysql_databases/localhost/mailcow' returned non-zero exit status 2.

I tried to connect to bormgatic container:
docker exec -it mailcowdockerized_borgmatic-mailcow_1 /bin/sh

I can see socket is mounted with this permissions:

-rw-rw----    1 5000     5000             2 Aug  3 11:07 mysqld.pid
srwxrwxrwx    1 5000     5000             0 Aug  3 11:07 mysqld.sock

When I try to login to mysql from borgmatic container I get same error.