Since version 0.0.18 Gretty supports multiple web-apps feature: it can start arbitrary number of web-apps on the same servlet-container. Gretty supports web-apps of various types: gradle projects, WAR-files in the file system and even WAR-files from maven dependencies.
Multiple web-apps feature also works nicely with integration tests and with the debugger.
The central concept of Multiple web-apps feature is farm - a collection of web-apps, that should run together.
There are two ways to define and use farms:
Default farm is automatically created for you by Gretty. You may add artbitrary web-apps to it and then invoke farm-specific tasks: farmRun, farmRunDebug, etc. Note that farm-specific tasks are not using gretty tasks (appRun, appRunDebug, etc.).
Named farms, which you create yourself in gradle script. You can add as many named farms as you want, and you can add web-apps to farms in arbitrary constellations. Each named farm provides a specific set of farm tasks. For example, if you define farm with name "XYZ", there will be new tasks farmRunXYZ, farmRunDebugXYZ, etc. available.
You can start using multiple web-apps support right away. Take Multiple web apps configureless setup as a starting point.