Docker simplify (phase 2)

[garth-wells]

Use a virtual env in the Dockerfile for installing dependencies. This is nicer than overwriting system Python packages when installing/updating. Will also allow advanced users to test Python package versions more freely.

[jorgensd]

I think this is a rather intrusive change, as all CIs must change from python3 to python for running code. Can't we use an alias so that we keep some backwards compatibility? I am not saying we should use venv, but is there a point of having another python3 in that environment, as it is bound to cause confusion.

All my CIs will now fail and need adjustment, and those that are customized to test against both stable and nightly can no longer be merged into a build matrix without extra arguments.

[garth-wells]

Why would a change python3 -> python be required?

[jorgensd]

Why would a change python3 -> python be required?

I inferred that from the changes in the CI, where you have replaced python3 -m pip with pip and python3 with python. Please let me know if I am mistaken, or if there is another motivation for this change.

[francesco-ballarin]

Will the script at https://github.com/FEniCS/dolfinx/blob/main/docker/dolfinx-real-mode (and similarly dolfinx-complex-mode) need adjustament?

I guess I am a bit confused of what having a venv will mean now for real vs complex build.

[garth-wells]

Why would a change python3 -> python be required?

I inferred that from the changes in the CI, where you have replaced python3 -m pip with pip and python3 with python. Please let me know if I am mistaken, or if there is another motivation for this change.

There should be no change required.

python3 -m pip is visual noise when pip is enough.

[jorgensd]

Why would a change python3 -> python be required?

I inferred that from the changes in the CI, where you have replaced python3 -m pip with pip and python3 with python. Please let me know if I am mistaken, or if there is another motivation for this change.

There should be no change required.

python3 -m pip is visual noise when pip is enough.

I dont necessarily agree, as by running pip you do not know what Python installation you are using.

Good to know that no changes are required. Is there a specific reason for the build docker and test Ci failing?