Postgres/Docker drops database

Hi
Dont know if its a Docker problem or a Postgres problem…

I have installed a Postgres container, installed Bitbucket container, and linked the two together.

After that I installed jira. And a jira database.
Both running fine.
Then I disconnected the Postgres server, and connected again. Then my Bitbucket DB was gone?

Anyone have a clue what happened?

Regards
J.