Root Configuration Directory

Payara Micro is distributed as a single JAR file. However, at runtime, it creates and depends on a folder structure that is referred to as Root Configuration Directory or rootdir.

This directory stores all of the instance configuration, deployed applications, as well as implementation JAR files needed for running the instance.

Temporary Root Configuration Directory

By default, Payara Micro will create a folder in the system’s temporary directory and prepares a root configuration directory there. This makes instances' configuration stateless, but also has two potentially undesirable effects:

  • Temporary directory may be deleted by system cleanup procedure. It is therefore important not to use a temporary directory in production scenarios. If files are removed by a third party process, the application will not behave correctly anymore.

  • Preparing the directory has an impact on startup time

Persistent Root Configuration Directory

Root configuration directory can be explicitly specified with the command line parameter --rootDir <directory>. In such case, the directory is created only once, and instance configuration is preserved across restarts of the instance.

Following configuration is preserved:

  • Deployed applications

  • Effects of preboot, postboot and post-deploy commands

  • Logging configuration