MAGECLOUD-3978: [Spike][Cloud Docker] DB data should persist in a volume

[oshmyheliuk]

Description

Fixed Issues (if relevant)

https://magento2.atlassian.net/browse/MAGECLOUD-3978

Manual testing scenarios

1. Install magento on docker, check that site works
2. Run docker-compose down
3. Run docker-compose up -d
4. Connect to mysql from db container and check that database exists
5. Check that Magento frontend is opening.
6. Check in production and developer modes.

https://jira.corp.magento.com/browse/MAGECLOUD-70

Contribution checklist

• Pull request has a meaningful description of its purpose
• All commits are accompanied by meaningful commit messages

[joeshelton-wagento]

Pros:

• Increase DB data persistence and prevent unintentional loss of data from the use of the "down" command. Instead users will need to use "docker volume rm" command to dispose of data, which is much more explicit.
• The volume has better namespacing. Frequent users of Docker have many volumes, and a volume named with random characters is difficult to manage.
• Named volume for DB is used by most of the Magento community Docker configurations. User switching to Magento's solution should not find that their usual workflows lead to data loss.
  https://github.com/meanbee/docker-magento2
  https://github.com/markshust/docker-magento

[ngreimel-lt]

I love it! LGTM

NIT: Could .docker/mysql/docker-entrypoint-initdb.d be mounted ro?

[mattskr]

As mentioned in the closed PR usually we use docker-compose stop to shut down the containers and leave our DB intact. We use docker-compose down to destroy/recreate.

This works fine for my developers workflow so I think all we need here is better documentation between down and stop.

[shiftedreality]

Thanks for the review! Moved to QA

[andriyShevtsov]

QA approved