Install docker https://docs.docker.com/install/linux/docker-ce/ubuntu/
Build the HAROS docker image, for your desired ROS distro version:
cd path-to-ros-model-extrcators-repo
[sudo] docker build --tag=haros_melodic -f melodic/Dockerfile .
Call the ros-model extractor plugin, remember you have to also clone the repository to be analysed:
[sudo] docker run -it haros_melodic:latest /haros_runner.sh *package_name* *node_name* *type* *path_to_resulted_model* *workspace_path* *github_repository* *branch*
For example:
[sudo] docker run -it haros_melodic:latest /haros_runner.sh hokuyo_node hokuyo_node node . /root/ws https://github.com/ros-drivers/hokuyo_node