#23344 2.32.0a1 uv resolver: remote cache hit can skip local `venv_cache` materialization Issue created by henridwyer Describe the bug With Pants

2.32.0a1

,

[python].resolver = "uv"

, and remote cache reads enabled, a clean reader can get a cache hit for

Create venv from uv lockfile ...

without materializing the local

venv_cache

. A later PEX build then tries to execute

.cache/venv_cache/.../bin/python

and fails with

No such file or directory

. This reproduces with Pants'

experimental-file

remote cache; I also saw the same failure with a REAPI/bazel-remote cache. Pants version 2.32.0a1 OS MacOS Additional info Minimal reproduction: Create three files: pants.toml [GLOBAL] pants_version = "2.32.0a1" backend_packages = ["pants.backend.python"] remote_provider = "experimental-file" remote_store_address = "file:///tmp/pants-uv-remote-cache-repro" [python] enable_resolves = true resolver = "uv" interpreter_constraints = ["==3.12.*"] [python.resolves] python-default = "uv.lock" requirements.txt

packaging>=24
typing-extensions>=4

test_smoke.py

from packaging.version import Version

def test_smoke():
    assert Version("1") < Version("2")

Generate BUILD and lockfile:

pants --no-pantsd tailor ::
pants --no-pantsd generate-lockfiles --resolve=python-default

Populate the remote cache:

rm -rf .pants.d ~/.cache/pants /tmp/pants-uv-remote-cache-repro
PANTS_REMOTE_CACHE_READ=false \
PANTS_REMOTE_CACHE_WRITE=true \
pants --no-pantsd test :tests0

Now edit test_smoke.py to add a second dependency from the same uv lockfile:

from packaging.version import Version
from typing_extensions import assert_never

def test_smoke():
    assert Version("1") < Version("2")
    assert assert_never

Read from remote cache with clean local state:

rm -rf .pants.d ~/.cache/pants
PANTS_REMOTE_CACHE_READ=true \
PANTS_REMOTE_CACHE_WRITE=false \
pants --no-pantsd test :tests0

Here I would expect pants to materialize the uv venv into local venv_cache, or avoid treating that venv creation process as remotely cacheable. Actually, the second run fails:

Canceled: Create venv from uv lockfile at uv.lock
Completed: Building 2 requirements for requirements.pex from the uv.lock resolve: packaging>=24, typing-extensions>=4

IntrinsicError: Failed to execute: Process {
    argv: [
        ".cache/venv_cache/.../python-default/.../bin/python",
        "./pex",
        ...
        "--venv-repository=.cache/venv_cache/...",
    ],
    append_only_caches: {
        CacheName("venv_cache"): RelativePath(".cache/venv_cache"),
    },
    cache_scope: Successful,
}

Error launching process: Os { code: 2, kind: NotFound, message: "No such file or directory" }

The clean reader's named_caches/venv_cache exists but is empty. pantsbuild/pants