Add Liquibase extension to Keycloak - wildfly

Question

I am trying to use the Keycloak docker image with a non-standard database (HANA-DB).
Modifying the configuration as described in the documentation worked fine and keycloak connects to the database. The remaining problem seems to be that the Liquibase migrations can not run because Liquibase does not know how to handle HANA-DB out of the box.
Of course, there is an extension library (https://mvnrepository.com/artifact/org.liquibase.ext/liquibase-hanadb/4.0.0) that adds this capability to Liquibase. Now my question: How do I get Keycloak's Liquibase to use this library?
I already tried:
Packaging the library into its own module and adding a dependency to it in Keycloak's Liquibase module
Adding the library as a second resource-root to Keycloak's Liquibase module
Both did not work, i.e. Liquibase is still not recognizing the "HDB" database.
What would be the correct way to do this?

Answer 1

I actually made it!
The way i achieved it is not perfekt, but keycloak 11.0.2 Docker Image is running.
Keycloak with Hana and Liquibase Migration to Hana DB is working and by now all tests for us have passed.
I'll just give you a short description what I did. And maybe write a little Blog Entry for that.
Basically you answer helped me at some point and you were on the right track.
What I did:
Creating another DB Vendor for JBoss CLI Bootstrap Scripting (https://medium.com/#victor.boaventura/keycloak-using-alternative-databases-e2b13576c457).
Hana DB Driver also needed a Global Module /subsystem=ee:write-attribute(name="global-modules",value=[{"name" => "jdk.net","slot" => "main"}, {"name" => "org.liquibase","slot" => "main"}]) (JBOSS CLI)
Keycloak did not autodiscover the correct Hibernate Dialect, so had to add that as well: /subsystem=keycloak-server/spi=connectionsJpa/provider=default/:write-attribute(name=properties,value={"dataSource" => "java:jboss/datasources/KeycloakDS","initializeEmpty" => "true","driverDialect" => "org.hibernate.dialect.HANAColumnStoreDialect","migrationStrategy" => "update","migrationExport" => expression "${jboss.home.dir}/keycloak-database-update.sql"})
Updated the Liquibase Module to Version 3.6.3 and added Liquibase Hana DB Adapter 3.9.0 (https://github.com/liquibase/liquibase-hanadb) as second resource root in same module. (Was kinda tricky to get the versions working) Also the Module needed another dependency on 'org.slf4j' to get the Logging to work.
At this Point I struggled with Liquibase Package Scanning and Keycloaks exclusion on 'liquibase.ext'. Thats why I had to add the SystemProp 'liquibase.scan.packages' (Thanks to you here :))
liquibase.scan.packages=org.keycloak.connections.jpa.updater.liquibase.lock,liquibase.change,liquibase.changelog,liquibase.database,liquibase.parser.core.xml,liquibase.precondition,liquibase.datatype,liquibase.serializer.core.xml,liquibase.sqlgenerator,liquibase.executor,liquibase.snapshot,liquibase.logging,liquibase.diff,liquibase.structure,liquibase.structurecompare,liquibase.lockservice,liquibase.sdk.database,liquibase.ext
After that Keycloak recognized Hana DB for Liquibase and the Migration started. I was super happy, but one Problem solved the next comes up...
2 of the liquibase changelogs were not working with Hana DB due to some SQL specifics. Thats why I created two patches and applied them to the keycloak-model-jpa module. Basically they already handled special cases (that failed) for oracle, so I just added 'hana' to every preCondition, where 'oracle' was mentioned and it worked!
This is basically my solution. If you have any questions please feel free to ask them here or contact me.

Answer 2

It turns out, that adding the library as a second resource-root in Keycloaks's liquibase module is actually working. It does not get loaded because Keycloak removes liquibase.ext from the service loader used to find liquibase extensions.
This can be worked around by using the liquibase.scan.packages system property, though.
For all those trying to make Keycloak working with HANA:
Overriding the liquibase.scan.packages system property causes the library to be loaded
Now, a class (LoggingService) from liquibase that is referenced in the liquibase-hanadb library, can not be found because it was introduced in liquibase 3.6 and Keycloak comes with 3.5.5.
When hacking a more recent version of liquibase (3.6.0) into Keycloak's modules, for some reason a changeset only intended for DB2 is being run, causing errors. I suspect an incompatibility between Keycloak's changelogs and the updated liquibase version.
I gave up at this point.