[BUG] rendering of dm_control fails on circleci #329
Description
Description
Rendering must be tested in headless mode in the CI. dm_control relies on mujoco for physic simulation and rendering. In turn, mujoco rendering can use one of the following backends (indicated by the env variable MUJOCO_GL=$backend)
backend=egl: supports headless rendering. Requires OpenGL /pyopengl.
backend=osmesa: supports headless rendering but slow
backend=glfw: does not support headless rendering
Problem
We used to rely on osmesa for rendering on gpu machines in circleci. Osmesa was installed with conda from menpo
conda install -c menpo osmesa
This command now fails due to an http error. Installing libmesa from conda-forge should work but the rendering stays idle in the tests, hence all gpu tests are failing.
We could try to use egl but this fails too because of an error described here: google-deepmind/mujoco#398
Strangely this error disappears when logging through ssh on the machine!
The solution should make it possible to run test_env.py without error.