How to install Torch CPU in Poetry

It sucks, at least for now.

Having a working poetry environment that installs only cpu supported versions of torch is a good way to reduce the size of your docker container and speed up deployments. The following is a rough solution but seems to work (locally on Mac and Docker container) and could be used while torch and poetry solve their compatibility issues.

Inside your regular pyproject.toml file, include in [tool.poetry.dependencies] the following torch definition:

torch = [
     {url="https://download.pytorch.org/whl/cpu/torch-2.0.0%2Bcpu-cp39-cp39-linux_x86_64.whl", markers="platform_system == \"Linux\""},
     {url="https://download.pytorch.org/whl/cpu/torch-2.0.0-cp39-none-macosx_10_9_x86_64.whl", markers="platform_system == \"Darwin\" and platform_machine == \"x86_64\""},
     {url="https://download.pytorch.org/whl/cpu/torch-2.0.0-cp39-none-macosx_11_0_arm64.whl", markers="platform_system == \"Darwin\" and platform_machine == \"arm64\""}
 ]

Why is such an ugly solution required? Here are some apparent torch-poetry compatibility issues:

• poetry install torch==2.0.1 omits required gpu drivers for linux, which makes the container small but unusable Pytorch 2.0.1 pypi wheel does not install dependent cuda libraries pytorch/pytorch#100974

• pip and poetry install by default torch-cpu in mac and torch-gpu in linux . When specifying https://download.pytorch.org/whl/cpu as package source to install torch-cpu-linux, Poetry is unable to find a torch-cpu-mac version to use (Does not find a *+cpu version for mac). poetry add with --index-url option python-poetry/poetry#7685, Instructions for installing PyTorch python-poetry/poetry#6409 (comment)

• poetry may have issues dynamically selecting python wheels based on platforms (doesn't happen if you use the wheel link) Install wheel based on platform python-poetry/poetry#1616

Here are some (so far) unsuccessful attempts to find a more elegant solution:

Attempt 1:

[tool.poetry.dependencies]
torch = { version = "2.0.0", source="torch"}

[[tool.poetry.source]]
name = "torch"
url = "https://download.pytorch.org/whl/cpu"
priority = "explicit" or "suplemental"

Attempt 2:

[tool.poetry.dependencies]
torch = [
     {version = "^2.0.0", platform = "darwin"},
     {version = "^2.0.0", platform = "linux", source = "torch"},
     {version = "^2.0.0", platform = "win32", source = "torch"},
]

[[tool.poetry.source]]
name = "torch"
url = "https://download.pytorch.org/whl/cpu"
priority = "explicit"

Attempt 3:

[[tool.poetry.source]]
name = "torch_cpu"
url = "https://download.pytorch.org/whl/cpu"
priority = "supplemental"

[[tool.poetry.source]]
name = "PyPI"
priority = "primary"

[tool.poetry.dependencies]
torch = { version = ">=2.0.0, !=2.0.1", source="torch_cpu" }

Attempt 4:

[[tool.poetry.source]]
name = "PyPI"
priority = "primary"

[[tool.poetry.source]]
name = "linux_cpu"
url = "https://download.pytorch.org/whl/cpu"
priority = "supplemental"

[tool.poetry.group.linux_cpu]
optional = true

[tool.poetry.group.linux_cpu.dependencies]
torch = { version = ">=2.0.0, !=2.0.1", source="linux_cpu"}

[tool.poetry.group.darwin_cpu]
optional = true

[tool.poetry.group.darwin_cpu.dependencies]
torch = { version = ">=2.0.0, !=2.0.1"}

In most attempts, the error was around the inability to find a torch-cpu-mac version to install when the https://download.pytorch.org/whl/cpu repo was included.