SAP Java Buildpack can automatically provide JDBC drivers for SAP HANA and PostgreSQL in the classpath if the respective service instance is bound.
The application can also provide its own version of these drivers in the relevant directory:
WEB-INF/lib– for standard Java applications. It's loaded for all Java buildpacksBOOT-INF/lib– for Spring Boot applications. It's only loaded for SAP Java Buildpack 2.
In this case, the application-provided version of the driver will be set in the classpath, not the one that comes with SAP Java Buildpack. The drivers have to follow the respective file name pattern:
- ngdbc*.jar – for SAP HANA Driver
- postgresql*.jar – for PostgreSQL JDBC Driver
When using this mechanism, the application developer is responsible to keep the drivers up-to-date.
The application developer can provide additional components alongside the aforementioned libraries. For example, this can be a custom SSL factory for the PostgreSQL JDBC Driver, which has to be accessible to the class loader that loads the actual library.
To do so, the additional libraries have to be placed in a JAR file in the WEB-INF/lib or BOOT-INF/lib directory. The JAR file has to follow the respective file name pattern:
- sjb-ngdbc-aux*.jar – for SAP HANA Driver
- sjb-postgresql-aux*.jar – for PostgreSQL JDBC Driver
Any number of files following these patterns can be placed in the WEB-INF/lib or BOOT-INF/lib directory and will be handled by SAP Java Buildpack.
This mechanism works with both application-provided and buildpack-provided libraries.