Liquibase requires JDBC drivers to connect to the different DBMSs it can manage
and they do not come with the liquibase binary distribution.

In order to add them to its classpath, you should put the JDBC driver jars (or
symlinks to them) in /opt/liquibase/lib/.

Please see http://www.liquibase.org/databases.html for a list of supported
DBMSs.