I'm wondering what solution(s) folks have arrived at for needing to run a

pex_binary

against the source code and modify the filesystem in-place. Specifically, I need to be able to run

django

management commands like

./pants run manage.py -- makemigrations

that writes out migrations files. I'm thinking the answer is that if I need to run side-effecting code like that that i need to do it via a pants plugin like other codegen tools?

Good question! Generally, I believe

./pants run

should work for mutating the build root - we do that in pantsbuild/pants, e.g. our

generate_github_workflows.py

script But for the sake of Django itself, @happy-kitchen-89482 has been working on creating an example Django repo and he is recommending running

manage.py

directly, at least for now. I don't yet totally understand why he came to this recommendation, but see https://github.com/pantsbuild/example-django/pull/2#discussion_r635578267 and I think a script to ensure things work properly

Following this. We currently run

makemigrations

in a super hacky way.

./pants run

 runs in a tmpdir under the chroot containing a copy of the relevant code. So  

makemigrations

 will create the migrations files under the tmpdir, which is not helpful...

./pants run

is allowed to mutate the repo, it's just that it can't do it in the right place.

A possible general-purpose solution is to optionally allow ./pants run to run against your actual sources.

The major complication I see there is codegen (including

relocated_files

) - we don't want to put those files in the actual build root. How was this achieved in v1? My first thought was "set the PYTHONPATH appropriately", but that doesn't work with

relocated_files

for example

@happy-kitchen-89482 would it be possible to have

run

discover newly created files in the tempdir and copy them back into the source tree? Right now we basically do that manually.

Hm, relevant: the tempdir approach already fails pretty badly with opening up loose files: https://github.com/pantsbuild/pants/issues/11109