It saves the changes you had done in Docker’s container.
Docker’s container are brief. It means that any change you make in a container must be saved in order that you could recover it the next time you start the container. GorillaJS doesn’t save automatically the changes you have done in the containers. It’s only worried about the app files the databases.
If you need to install new libraries in a container or increase the usefulness that GorillaJS has automatically you can use this plugin to save the changes. You can also order to GorillaJS that the next time the project starts will have to use the modified container.