[DOC] - Usage of opencv requires unique env build

[kcpevey]

Preliminary Checks

• This issue is not a question, feature request, RFC, or anything other than a bug report. Please post those things in GitHub Discussions: https://github.com/nebari-dev/nebari/discussions

Summary

In order to use opencv on Nebari, you need some additional libraries (OpenGL) that are not packaged with opencv on conda-forge.

If you only specify opencv in your environment, you'll get an error when you try to run import cv2:

---------------------------------------------------------------------------
ImportError                               Traceback (most recent call last)
Cell In[3], line 1
----> 1 import cv2

ImportError: libOpenGL.so.0: cannot open shared object file: No such file or directory

Steps to Resolve this Issue

Instead of installing opencv in your environment, you can install libopencv headless, like this:

channels:
  - conda-forge
dependencies:
  - python=3.10
  - libopencv *=headless*

We should document this process, probably as an FAQ, since we have a lot of users who are interested in opencv.