feat: add a virtual environment rule

python/BUILD

@@ -1,8 +1,14 @@
 py_binary(
     name = "poetry_deps",
     srcs = ["poetry_deps.py"],
-    visibility = ["//visibility:public"],
+    visibility = ["__subpackages__"],
     deps = [
         "@rules_poetry_pip//:pkg",
     ],
 )
+
+py_binary(
+    name = "py_venv",
+    srcs = ["py_venv.py"],
+    visibility = ["__subpackages__"],
+)

python/py_venv.bzl

@@ -0,0 +1,48 @@
+def _py_venv_impl(ctx):
+    """
+    Rule to link Python package into a virtual environment.
+
+    Arguments:
+        ctx: The rule context.
+
+    Attributes:
+        deps: label_list The package dependencies list.
+
+    Private attributes:
+        _py_venv:
+
+    Returns:
+        The providers list or a tuple with a venv package.
+    """
+
+    deps = ctx.attr.deps
+    output = ctx.actions.declare_directory("venv/{}".format(ctx.label.name))
+    import_paths = ["{}/external/{}".format(ctx.bin_dir.path, path) for dep in deps for path in dep[PyInfo].imports.to_list()]
+
+    ctx.actions.run(
+        outputs = [output],
+        inputs = ctx.files.deps,
+        mnemonic = "CreateVenv",
+        progress_message = "Creating venv {}".format(ctx.label.name),
+        arguments = [output.path] + import_paths,
+        use_default_shell_env = True,
+        executable = ctx.executable._py_venv,
+    )
+
+    transitive_depsets = [dep[PyInfo].transitive_sources for dep in deps]
+    runfiles = [output] + [item for dep in transitive_depsets for item in dep.to_list()]
+    files = depset([output], transitive = transitive_depsets)
+
+    return [
+        DefaultInfo(files = files, runfiles = ctx.runfiles(files = runfiles)),
+        PyInfo(transitive_sources = files, imports = depset(["_main/" + output.short_path])),
+    ]
+
+py_venv = rule(
+    implementation = _py_venv_impl,
+    provides = [PyInfo],
+    attrs = {
+        "deps": attr.label_list(doc = "The package dependencies list"),
+        "_py_venv": attr.label(default = ":py_venv", cfg = "exec", executable = True),
+    },
+)

python/py_venv.py

@@ -0,0 +1,30 @@
+import argparse
+from pathlib import Path
+
+SKIP_SET = {"requirements.txt"}
+MERGE_SET = {"bin"}
+
+if __name__ == "__main__":
+    parser = argparse.ArgumentParser(description="Download and install a Poetry package")
+
+    parser.add_argument("venv", type=Path, help="output environment directory")
+    parser.add_argument("path", type=Path, nargs="*", help="package path")
+
+    args = parser.parse_args()
+
+    args.venv.mkdir(parents=True, exist_ok=True)
+    for path in args.path:
+        if not path.exists():
+            raise RuntimeError(f"Required {path} does not exist")
+
+        for item in path.iterdir():
+            name = item.name
+            if name in SKIP_SET:
+                continue
+            if name in MERGE_SET:
+                continue  # TODO
+
+            # Requires permits_treeartifact_uplevel_symlinks feature
+            symlink_path = args.venv / name
+            target_path = item.relative_to(args.venv, walk_up=True)
+            symlink_path.symlink_to(target_path, target_is_directory=True)