Possebility of corrupted mysqldump when using docker

[TheOneRing]

WHAT Needs to be Documented?

When following the instructions to create a mysqldump with docker

docker-compose exec mariadb \
     /usr/bin/mysqldump -u root --password=owncloud \
     owncloud > owncloud_$(date +%Y%m%d).sql

The process appears to be stuck and when it eventually finishes the dump is corrupted,
namely only the table definitions made it to the dump, not the data.

Adding -T to the exec however solves that issue

docker-compose exec -T mariadb \
     /usr/bin/mysqldump -u root --password=owncloud \
     owncloud > owncloud_$(date +%Y%m%d).sql

https://docs.docker.com/compose/reference/exec/

Dumping in a non interactive shell works without a problem.

WHERE Does This Need To Be Documented (Link)?

https://doc.owncloud.com/server/next/admin_manual/installation/docker/

WHY Should This Change Be Made?

Working backups are kind of important

(Optional) What Type Of Content Change Is This?

• New Content Addition
• Old Content Deprecation
• Existing Content Simplification
• Bug Fix to Existing Content

(Optional) Which Manual Does This Relate To?

• Admin Manual
• Developer Manual
• User Manual
• Android
• iOS
• Branded Clients
• Desktop Client
• Other