[keycloak-dev] Connecting to an external database for a ProtocolMapper

[Thomas]

I need help finding the correct direction of creating a ProtocolMapper that
reads from an external database.

We currently have a Spring microservice application that uses Spring OAuth2
secured services with a Spring OAuth2 server that adds claims to the access
token to implement extra claims for security.  The application also reads
the extra claims from the user service database.  This database doesn't
store user authentication credentials. User authentication data is in an
enterprise LDAP/AD that is read only.  I will never be able to change the
read only LDAP.  We would like to get rid of the Spring OAuth2 server.

So far, I've been able to import users into Keycloak from the LDAP and get
every microservice to respond correctly to a request from a valid token
from Keycloak once a login has happened.  I've also been able to get a
ProtocolMapper running that adds hard coded claims to the user's access
token.

I would like to use a few custom Spring libraries that we have created for
other services to read data from the User Service Database.  The libraries
all ready have implemented a ReadOnly Repository that has custom SQL
types.  Particularly,  arrays of strings and ints.  As well as the Domain
model.

Should I create an EAR that includes the ProtocolMapper as a jar module?
What is the correct way to structure the EAR?  Will using my other
libraries that use Spring work?

Thanks,
Thomas