I deployed a couple of mariadb services and was surprised to find out that its variables, and especially passwords, are identical across all deployments.

i.e. I deployed the wordpress template from the marketplace and a standalone mariadb directly from hub.docker.com and found out that all passwords are identical.

Is this voluntary? (feels a bit of a potential security issue but I may miss something)

(fwiw search didn't bring up any previous discussions)