Immitate pip install --no-deps / Add --only-root

[Natureshadow]

• 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.

Feature Request

It would be great if Poetry could support installing only the root of the project, but leave all dependencies untouched, much like the --no-deps option to pip does.

The use case is a development environment where the code being worked on is spread across several packages, and I want to keep several of them editable in the same poetry environment without having to temporarily change/remove a dependency from pyproject.toml.

Poetry ould optionally still check whether the installed packages fulfill the dependencies or not, but with such an option that developers will explicitly use, this is not necessary I suppose.

[sinoroc]

To make sure I understand, you have tried the following and it does not fit your workflow, right?

[tool.poetry.dependencies]
# ...
library = "^0.1.0"

[tool.poetry.dev-dependencies]
library = {path = "../library", develop = true}

[Natureshadow]

Well, this is a nice hack, but it would require one of manipulating pyproject.toml every time I start developing on such a situation, or forcing relative paths on every developer in the project (given that the library is, or might be, in a different Git repository/whatever).

[wom]

I'd like to add a +1 here; sometimes upstream packages are too conservative when pinning dependencies. I'd rather avoid having to add a pip install --no-dep <package==... after my initial poetry install.

[cglacet]

Does anyone found a way to prevent install sub-dependencies? It would also be interesting when trying to generate documentation for another package (where you only want to be able to read the package's code).

My current fix is to put all the concerned package in my dev-dependencies, then run poetry with --no-dev and use pip to install the dependencies from a (git) submodule directory.

In my CI job, that looks like:

poetry install --no-dev -vv
git submodule sync --recursive
git submodule update --init --recursive
poetry run python -m pip install --no-deps submodules/*

[Badg]

Just adding another +1 for a different use case: multi-stage installations for quicker docker builds. Basically, the logic is, at my dayjob we build a new docker image for every code change, which means docker build time can be pretty important. Our application code changes a lot more frequently than our dependencies, so we split the install into two different phases: first, the dependencies, and then, the root project. That way, when all we have is changes in the application code, the docker image builder doesn't need to reinstall dependencies on every build. Hopefully that explanation makes sense (if you're familiar with docker anyways).

The relevant bit of our dockerfile currently looks like this (side note: I personally would rather be distributing the application package as a first-class python package hosted on a private package index, but that's a completely separate conversation that has nothing to do with poetry!):

# Copy and install the project definition and deps first, so that we
# don't need to re-run this step if we only changed our application code.
# Note that this is installed into a clean virtualenv
COPY pyproject.toml .
COPY poetry.lock .
RUN poetry install --no-root --no-dev

# copy the rest and install our application package
COPY . .
RUN poetry run pip install --no-dependencies .

What I'd love to see instead, is something like this:

COPY pyproject.toml .
COPY poetry.lock .
RUN poetry install --no-root --no-dev
COPY . .
RUN poetry install --only-root

Edit: I'm stupid busy right now, so I can't put together a PR, but if in a month or two I have some free time and nobody else has closed this, would the maintainers be open to a PR?

[cmin764]

I'm interested into this!

Use case: installing locally for development a package that requires a main dependency which isn't available anymore given the upgraded Python interpreter version for this local case only. Therefore I'm manually installing another version of the dependency, one that is available but can't continue on poetry install the project itself because that specific pinned down dependency version isn't satisfied. (and I don't want to edit pyproject.toml or the lock file neither)

[iamhatesz]

@Badg 100% agree with this use case. I noticed the same issue in our setup, where we have a tons of heavy ML libraries, which we'd like to avoid downloading each time.

[caniko]

+1

[abn]

Poetry on master should make this possible, albeit, via misfeature.

poetry install --only=non-existent-group

[Maciej-Zwolinski]

Yet Another Use Case:

Since poetry does not recognize torch==1.10.2+cu113 as satisfying torch>=1.10.2 it'd be great to force poetry to ignore dependencies for packages that require specific versions of torch.

[MikiGrit]

I'm also interested in this functionality.

Our usecase... pytorch-toolbelt depends on any opencv package and have specified opencv-python as a dependency. This is unfortunately problem for us since the opencv-python package have also dependency on OpenGL library which is difficult to install in our Gitlab CI. On the other hand it would be perfectly fine to install non-opengl variant (opencv-python-headless) ourselves but we also need a way how to tell poetry that we don't want to install dependencies for pytorch-toolbelt.

[cristianmtr]

Is this possible now? Couldn't figure it out from perusing the docs. We hit the problem:

• we have project A
• project A has a dependency on project B
• proj B has strict dependencies (versions) on projects C, D, etc.
• in proj A we don't want to install the specific versions of projects C, D, etc. that proj. B requires, but use other versions

Currently we solve this by having a two-step process (in proj. A):

pip install -e .[dev,whatever,etc.]
pip install --no-deps projB

It would be nice to find a packaging system that can add the --no-deps functionality in the requirements file itself (setup.py, project.toml, etc.)

[sinoroc]

@cristianmtr There is now poetry install --only-root:

• https://python-poetry.org/docs/cli/#options-2
• Add --only-root option to install command, excluding all dependencies. #5783

[cristianmtr]

@cristianmtr There is now poetry install --only-root:

* https://python-poetry.org/docs/cli/#options-2

* [Add `--only-root` option to install command, excluding all dependencies. #5783](https://github.com/python-poetry/poetry/pull/5783)

But this is only for the installation of the main project (project A) itself, not for the installation of dependencies (project B).

How can I add a dependency in my pyproject.toml and specify that I want to do --only-root for that dependency (project B in my above example).

[charlienewey-odin]

As @Maciej-Zwolinski has said, this poses difficulties for when certain libraries have unusual package suffixes.

For example, the official NVIDIA PyTorch image (nvcr.io/nvidia/pytorch:23.12-py3) comes preconfigured with at least 3 packages that cause errors:

numba = "0.57.1+1.g4157f3379"
torch = "2.2.0a0+81ea7a4"
torchvision = "0.17.0a0"

This makes poetry a bit frustrating to use in some edge cases, because poetry doesn't detect them as "valid"

[Natureshadow]

It seems for such cases, an override mechanism for recursive dependencies would be more appropriate.

[caniko]

I would recommend opening a separate issue for this problem

[sinoroc]

But this is only for the installation of the main project (project A) itself, not for the installation of dependencies (project B).

If it is for dependencies, then yes it needs a different GitHub issue, yes.

It seems for such cases, an override mechanism for recursive dependencies would be more appropriate.

I started a discussion on this here (not limited to Poetry): https://discuss.python.org/t/proposal-overrides-for-installers/23666

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