Feature or enhancement
Proposal:
The central idea is to allow a venv to be relocatable between different hosts by using a relative path in pyvenv.cfg for the home value. Relative paths allow avoiding use of an absolute path that is likely host-specific. Concretely, I propose making a relative home value relative to the pyvenv.cfg file.
Today, the home key is officially documented to be an absolute path. If a relative path is used, then official behavior is undefined. In practice, it is treated as relative to the current working directory (so, in effect, could be anywhere). (By omitting the home key entirely (#135773), it gets computed based on the bin/python3 symlink, but this is undesirable behavior).
I think there's a variety of things this enables or otherwise makes much simpler. The main one that comes to mind is that multiple venvs can efficiently share a runtime (while still being host-relocatable). Not needing a system Python itself to create the venv is another benefit. The explicitly looser coupling between the venv and system state (i.e where the desired Python is) is also appealing.
For the runtime itself, making relative home paths work is simple and about 2 lines. See main...rickeylev:cpython:feat.relative.pyvenv.home
As the python-ideas discussion points out, other parts of venv creation and dependency installation would also need to be aware of this.
I expect a PEP will be requested, so I'll start on that and put more details there rather than here.
Parties that should probably be part of the discussion:
Related
Has this already been discussed elsewhere?
I have already discussed this feature proposal on Discourse
Links to previous discussion of this feature:
https://discuss.python.org/t/making-venvs-relocatable-friendly/96177
https://discuss.python.org/t/q-what-stops-a-venv-from-being-relocatable/57166
Feature or enhancement
Proposal:
The central idea is to allow a venv to be relocatable between different hosts by using a relative path in
pyvenv.cfgfor thehomevalue. Relative paths allow avoiding use of an absolute path that is likely host-specific. Concretely, I propose making a relativehomevalue relative to the pyvenv.cfg file.Today, the
homekey is officially documented to be an absolute path. If a relative path is used, then official behavior is undefined. In practice, it is treated as relative to the current working directory (so, in effect, could be anywhere). (By omitting the home key entirely (#135773), it gets computed based on thebin/python3symlink, but this is undesirable behavior).I think there's a variety of things this enables or otherwise makes much simpler. The main one that comes to mind is that multiple venvs can efficiently share a runtime (while still being host-relocatable). Not needing a system Python itself to create the venv is another benefit. The explicitly looser coupling between the venv and system state (i.e where the desired Python is) is also appealing.
For the runtime itself, making relative home paths work is simple and about 2 lines. See main...rickeylev:cpython:feat.relative.pyvenv.home
As the python-ideas discussion points out, other parts of venv creation and dependency installation would also need to be aware of this.
I expect a PEP will be requested, so I'll start on that and put more details there rather than here.
Parties that should probably be part of the discussion:
Related
uv venv --relocatable. From a cursory look, the basic thing it does is generate "relative aware" scripts inbin/and put arelocatable=truesetting in pyvenv.cfg.Has this already been discussed elsewhere?
I have already discussed this feature proposal on Discourse
Links to previous discussion of this feature:
https://discuss.python.org/t/making-venvs-relocatable-friendly/96177
https://discuss.python.org/t/q-what-stops-a-venv-from-being-relocatable/57166