`.hegel` venv issues with containerized development

[kejadlen]

Installed and ran hegel in a container, but then trying to run the tests outside the container results in this error (and vice versa):

---- vec_structs_roundtrip stdout ----

thread 'vec_structs_roundtrip' (31955226) panicked at .../.cargo/registry/src/index.crates.io-1949cf8c6b5b557f/hegeltest-0.2.0/src/runner.rs:557:14:
Failed to spawn hegel at path .hegel/venv/bin/hegel: Os { code: 2, kind: NotFound, message: "No such file or directory" }

[DRMacIver]

Thanks for the report!

Some notes on what's happening here: Basically because we create a .venv inside .hegel, if it's created on what's functionally a different computer, it will have links to python interpreters that don't exist. The NotFound isn't actually the hegel server, but the python interpreter it's trying to run on.

We clearly need to handle this case and give a better error message, but we also need to be better about not triggering this problem in the first place. This is a very normal workflow and it should ideally Just Work rather than erroring.

One alternative implementation we considered and didn't implement is to put hegel core instances on $XDG_CACHE/hegel-core/<version>/ or similar, which would be much less likely to hit this problem because people don't generally share XDG_CACHE with containers because that would break a huge amount of software. Still need a better error message when someone makes the regrettable life choice of doing so, but I think it's totally fine to just error in this case.

[Liam-DeVoe]

To enumerate all our options: One option is to check if the venv path is valid, and print a warning + recreate it if not.

[DRMacIver]

To enumerate all our options: One option is to check if the venv path is valid, and print a warning + recreate it if not.

I think this option is bad, because it breaks incredibly messily if you try to concurrently run the tests inside and out of the container.

(Which is totally a thing I do sometimes)