openmpi run as a non-root user

[caizexin]

When I tried to run python spinup/examples/bench_ppo_cartpole.py as said in homework 1, it failed as the openmpi command called by the python code raised an error saying that openmpi could not run as a root user. link to this issue

It works when I use an alternative command python -m spinup.run ppo --env CartPole-v0, otherwise I need to add a new user, switch the user and run the code.

[qiaoximing]

I find an easier solution for the OpenMPI's root user issue.
If you dig into Spinningup's source code, you'll notice that it calls mpirun in only one place, which is line 31, spinningup/spinup/utils/mpi_tools.py.
Changing args = ["mpirun", "-np", str(n)] to args = ["mpirun", "--allow-run-as-root", "-np", str(n)] solves the problem.