According to the README docker is a dependency of the wrapper. Moreover, VRE_RUNNER checks whether it is installed. However, disabling this check and running the executor works fine so I suspect docker is not really a dependency.

• Is it only required to run the basic test in /tests/basic? If so, I suggest we stop considering it a dependency.

It needs to compress the results returned by VRE tools if their tools return a directory.

Compressions will be made in zip format.

When cwltool is run with the singularity option, and the container is a docker container, a .sif file is created, which must be saved in a temporary folder. Therefore, this folder must be created and validated if the container already exists in it.

Is a new use case that to add, a data entity must be created to the RO-Crate for each item in input_files that it is a list:

The VRE_RUNNER bash script does two things that seem contradictory:

1. Checks if cwltool is available: type -a "$prog" >/dev/null in line 17
2. Activates virtual environment: source "$BASEDIR"/venv/bin/activate in line 26

These two steps are contradictory because for cwltool to be available it has to be installed globally or the virtual environment has to be activated first. I don't think we want cwltool to be installed globally so I would suggest that we revamp the script so that it first activates de environment and it then checks whether cwltool is installed.