fix(whl_library): remove --no-index and add --no-build-isolation when build sdist (bazel-contrib#2126)

Building sdist results in `Could not find a version that satisfies the
requirement setuptool` this regressed when a fix in parameter handling
got introduced in bazel-contrib#2091.

Before this change the building from sdist when using
`experimental_index_url`
would break because `--no-index` is passed to `pip`. This means that
`pip`
would fail to locate build time dependencies needed for the packages and
would
just not work. In `whl_library` we setup `PYTHONPATH` to have some build
dependencies available (like `setuptools`) and we could use them during
building from `sdist` and to do so we need to add `--no-build-isolation`
flag.
However, for some cases we need to also add other build-time
dependencies (e.g.
`flit_core`) so that the building of the wheel in the `repository_rule`
context
is successfuly. Removing `--no-index` allows `pip` to silently fetch the
needed
build dependencies from PyPI if they are missing and continue with the
build.

This is not a perfect solution, but it does unblock users to use the
`sdist`
distributions with the experimental feature enabled by using
`experimental_index_url` (see bazel-contrib#260 for tracking of the completion).

Fixes bazel-contrib#2118
Fixes bazel-contrib#2152

---------

Co-authored-by: aignas <[email protected]>

Author: ewianda

CHANGELOG.md

@@ -28,6 +28,9 @@ A brief description of the categories of changes:
 * (gazelle): Update error messages when unable to resolve a dependency to be more human-friendly.
 
 ### Fixed
+* (whl_library): Remove `--no-index` and add `--no-build-isolation` to the
+  `pip install` command when installing a wheel from a local file, which happens
+  when `experimental_index_url` flag is used.
 * (bzlmod) get the path to the host python interpreter in a way that results in
   platform non-dependent hashes in the lock file when the requirement markers need
   to be evaluated.

examples/bzlmod/MODULE.bazel.lock

@@ -227,8 +227,10 @@ def _whl_library_impl(rctx):
             whl_path = rctx.path(rctx.attr.filename)
         else:
             # It is an sdist and we need to tell PyPI to use a file in this directory
-            # and not use any indexes.
-            extra_pip_args.extend(["--no-index", "--find-links", "."])
+            # and, allow getting build dependencies from PYTHONPATH, which we
+            # setup in this repository rule, but still download any necessary
+            # build deps from PyPI (e.g. `flit_core`) if they are missing.
+            extra_pip_args.extend(["--no-build-isolation", "--find-links", "."])
 
     args = _parse_optional_attrs(rctx, args, extra_pip_args)
 

python/private/pypi/whl_library.bzl

@@ -0,0 +1,20 @@
+load("@bazel_skylib//rules:build_test.bzl", "build_test")
+load("@dev_pip//:requirements.bzl", "all_requirements")
+load(":transitions.bzl", "transition_rule")
+
+build_test(
+    name = "all_requirements_build_test",
+    targets = all_requirements,
+)
+
+# Rule that transitions dependencies to be built from sdist
+transition_rule(
+    name = "all_requirements_from_sdist",
+    testonly = True,
+    deps = all_requirements,
+)
+
+build_test(
+    name = "all_requirements_from_sdist_build_test",
+    targets = ["all_requirements_from_sdist"],
+)

tests/pypi/evaluate_markers/BUILD.bazel

@@ -0,0 +1,24 @@
+""" Define a custom transition that sets the pip_whl flag to no """
+
+def _flag_transition_impl(_settings, _ctx):
+    return {"//python/config_settings:pip_whl": "no"}
+
+flag_transition = transition(
+    implementation = _flag_transition_impl,
+    inputs = [],
+    outputs = ["//python/config_settings:pip_whl"],
+)
+
+# Define a rule that applies the transition to dependencies
+def _transition_rule_impl(_ctx):
+    return [DefaultInfo()]
+
+transition_rule = rule(
+    implementation = _transition_rule_impl,
+    attrs = {
+        "deps": attr.label_list(cfg = flag_transition),
+        "_allowlist_function_transition": attr.label(
+            default = "@bazel_tools//tools/allowlists/function_transition_allowlist",
+        ),
+    },
+)