How to use Custom Database?

[涂鸦]

According to the official doc https://www.keycloak.org/server/db, that keycloak supports natively five databases, but I am not sure if it also supports custom databases through the jdbc driver.

There is a so-called DM database (https://eco.dameng.com/download/) that I want to use, I downloaded the docker image and corresponding jdbc driver, but when I try to start the keycloak by `docker compose -f docker-compose.local-DM.yml up`, I got the error message saying:

```

keycloak-heroku-keycloak-1  | ERROR: Failed to run 'build' command.
keycloak-heroku-keycloak-1  | ERROR: No value present
keycloak-heroku-keycloak-1  | For more details run the same command passing the '--verbose' option. Also you can use '--help' to see the details about the usage of the particular command.

```

The docker compose file and Dockerfile are as attached.

Is it possible to make it run from the DM database? How should I fix the issues? What does the No value present error message mean?

Or is it not possible so I should give up?

Thanks in advance for any comments!