Currently the distutils setup.py only installs the opsmop package, and none of its sub-packages resulting in the entrypoint script not being able to find the opsmop.client.cli module.
Normally I use setuputils as it has the find_pakages() function so that you don't have to add all of the packages by hand, and the python packaging guide recommends the use of setuputils as well. Additionally, setuputils will allow pip to resolve dependencies on it's own. Is there any reason we wanted to avoid setuputils aside from adding a setup dependency? If we are okay with switching I would be happy to submit a PR to get installs working on Linux systems.