prep_conf() {

    ...    

    # if we are stopping and starting, we just read the env vars and we done

    if [ -f /opt/grouper/grouperEnv.sh ]

      then

        echo "grouperContainer; INFO: (libraryPrep.sh-prep_conf) Loading env vars from /opt/grouper/grouperEnv.sh"

        . /opt/grouper/grouperEnv.sh

        return

    fi

    prep_initDeprecatedEnvVars

    grouperScriptHooks_prepConfPost

}

Note that if /opt/grouper/grouperEnv.sh exists, the function returns early. However, even in the base image the file exists with zero bytes. Thus, grouperScriptHooks_prepConfPost is never called.

The next opportunity to call a hook is setupFilesPost, which happens after file manipulation. So there is no way to add any hooks for setup that setupFiles can act on.

The other opportunity to call a hook before Grouper does file configuration is prepComponentPost. The setupFilesPost hook happens after Grouper file manipulation.