exporting packages to stdout adds 'creating virtualenv ...' in v 1.2.0

[jegger]

• I have searched the issues of this repo and believe that this is not a duplicate.
• I have searched the documentation and believe that my question is not covered.

Issue

Not sure if that should be considered a bug - maybe more an annoying change. However it broke our pipelines this morning as the new version 1.2.0 came out :)
I don't mind if you close this in case you think that it should be like that. Maybe it is helpful for others which use poetry in the same way we do.

We pipe the output of package export to pip for installation.
E.g. poetry export -f requirements.txt | poetry run pip install -r /dev/stdin

In case there is not virtualenv created yet, poetry prints to stdout Creating virtualenv foobar-pyXX in /foo/bar which will result in pip trying to install a package called "Creating virtualenv...", which then ofc. fails.

Workaround

As a workaround, we can simply export the dependencies to a file, and use pip to query the file instead of stdin.
poetry export -f requirements.txt --output requirements.txt && poetry run pip install -r requirements.txt

Thanks!

[neersighted]

Likely related to the plugin migration. Going to tag in @finswimmer as he was doing work on environment commands (and implicit environment creation) recently.

[dimbleby]

-o requirements.txt was always the contract: IMO this is indeed "annoying change" rather than "bug".

That poetry export creates an unnecessary virtual environment is covered at python-poetry/poetry-plugin-export#78. You can run the command with POETRY_VIRTUALENVS_CREATE=false to avoid that, if you care to do so.

[dimbleby]

Also --quiet, probably

[alex]

FWIW -o doesn't seem to be compatible with using the results with pip's -c: pyca/cryptography#7553 (the certbot-josepy job)

[dimbleby]

you want pip install -r not pip install -c and this is nothing to do with whether the file came via stdout or not. The output format is requirements.txt, not constraints.txt

[alex]

This was working under the previous version of poetry with the > constraints.txt operation. This thread suggests that the redirect was never supported, and -o should be used. Perhaps constraints.txt was never supported in either of them, but just happened to work?

[dimbleby]

I don't know how to be clearer so I guess I'll just repeat myself. The output format is (and always was) requirements.txt, not constraints.txt.

[adferrand]

I am a little confused here. The poetry documentation about export states that if the --output flag is omitted, stdin will be used. So we should be able to pipe the result of poetry export to pip via the -c or -r flag no ?

To clarify about pip -c, an interesting usage of poetry export is to generate the dependency tree maintained by poetry into an understandable format for pip (the so-called "requirements.txt" format), then use the -c flag of pip to have reproducible pip install (typically in CI/CD pipelines).

[dimbleby]

pip install -c expects a different input format than pip install -r. poetry export produces the latter format. If it used to work with pip install -c then that was just lucky.

This is nothing to do with the stdout / --output thing (and this whole discussion doesn't belong in this issue at all)

[neersighted]

Closing this as duplicate -- the bug is tracked at python-poetry/poetry-plugin-export#78 and things have gone off-topic.

[github-actions]

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