diff --git a/CHANGELOG.md b/CHANGELOG.md index 94487219bc..a6ba65eb2f 100644 --- a/CHANGELOG.md +++ b/CHANGELOG.md @@ -102,6 +102,8 @@ END_UNRELEASED_TEMPLATE * (pypi) Starlark-based evaluation of environment markers (requirements.txt conditionals) available (not enabled by default) for improved multi-platform build support. Set the `RULES_PYTHON_ENABLE_PIPSTAR=1` environment variable to enable it. +* (utils) Add a way to run a REPL for any `rules_python` target that returns + a `PyInfo` provider. {#v0-0-0-removed} ### Removed diff --git a/docs/index.md b/docs/index.md index b10b445983..285b1cd66e 100644 --- a/docs/index.md +++ b/docs/index.md @@ -101,6 +101,7 @@ pip coverage precompiling gazelle +REPL Extending Contributing support diff --git a/docs/repl.md b/docs/repl.md new file mode 100644 index 0000000000..edcf37e811 --- /dev/null +++ b/docs/repl.md @@ -0,0 +1,66 @@ +# Getting a REPL or Interactive Shell + +rules_python provides a REPL to help with debugging and developing. The goal of +the REPL is to present an environment identical to what a {bzl:obj}`py_binary` creates +for your code. + +## Usage + +Start the REPL with the following command: +```console +$ bazel run @rules_python//python/bin:repl +Python 3.11.11 (main, Mar 17 2025, 21:02:09) [Clang 20.1.0 ] on linux +Type "help", "copyright", "credits" or "license" for more information. +>>> +``` + +Settings like `//python/config_settings:python_version` will influence the exact +behaviour. +```console +$ bazel run @rules_python//python/bin:repl --@rules_python//python/config_settings:python_version=3.13 +Python 3.13.2 (main, Mar 17 2025, 21:02:54) [Clang 20.1.0 ] on linux +Type "help", "copyright", "credits" or "license" for more information. +>>> +``` + +See [//python/config_settings](api/rules_python/python/config_settings/index) +and [Environment Variables](environment-variables) for more settings. + +## Importing Python targets + +The `//python/bin:repl_dep` command line flag gives the REPL access to a target +that provides the {bzl:obj}`PyInfo` provider. + +```console +$ bazel run @rules_python//python/bin:repl --@rules_python//python/bin:repl_dep=@rules_python//tools:wheelmaker +Python 3.11.11 (main, Mar 17 2025, 21:02:09) [Clang 20.1.0 ] on linux +Type "help", "copyright", "credits" or "license" for more information. +>>> import tools.wheelmaker +>>> +``` + +## Customizing the shell + +By default, the `//python/bin:repl` target will invoke the shell from the `code` +module. It's possible to switch to another shell by writing a custom "stub" and +pointing the target at the necessary dependencies. + +### IPython Example + +For an IPython shell, create a file as follows. + +```python +import IPython +IPython.start_ipython() +``` + +Assuming the file is called `ipython_stub.py` and the `pip.parse` hub's name is +`my_deps`, set this up in the .bazelrc file: +``` +# Allow the REPL stub to import ipython. In this case, @my_deps is the hub name +# of the pip.parse() call. +build --@rules_python//python/bin:repl_stub_dep=@my_deps//ipython + +# Point the REPL at the stub created above. +build --@rules_python//python/bin:repl_stub=//path/to:ipython_stub.py +``` diff --git a/docs/toolchains.md b/docs/toolchains.md index c8305e8f0d..121b398f7a 100644 --- a/docs/toolchains.md +++ b/docs/toolchains.md @@ -757,3 +757,13 @@ a fixed version. The `python` target does not provide access to any modules from `py_*` targets on its own. Please file a feature request if this is desired. ::: + +### Differences from `//python/bin:repl` + +The `//python/bin:python` target provides access to the underlying interpreter +without any hermeticity guarantees. + +The [`//python/bin:repl` target](repl) provides an environment indentical to +what `py_binary` provides. That means it handles things like the +[`PYTHONSAFEPATH`](https://docs.python.org/3/using/cmdline.html#envvar-PYTHONSAFEPATH) +environment variable automatically. The `//python/bin:python` target will not. diff --git a/python/bin/BUILD.bazel b/python/bin/BUILD.bazel index 57bee34378..30af7d1b9f 100644 --- a/python/bin/BUILD.bazel +++ b/python/bin/BUILD.bazel @@ -1,4 +1,5 @@ load("//python/private:interpreter.bzl", _interpreter_binary = "interpreter_binary") +load("//python/private:repl.bzl", "py_repl_binary") filegroup( name = "distribution", @@ -22,3 +23,35 @@ label_flag( name = "python_src", build_setting_default = "//python:none", ) + +py_repl_binary( + name = "repl", + stub = ":repl_stub", + visibility = ["//visibility:public"], + deps = [ + ":repl_dep", + ":repl_stub_dep", + ], +) + +# The user can replace this with their own stub. E.g. they can use this to +# import ipython instead of the default shell. +label_flag( + name = "repl_stub", + build_setting_default = "repl_stub.py", +) + +# The user can modify this flag to make an interpreter shell library available +# for the stub. E.g. if they switch the stub for an ipython-based one, then they +# can point this at their version of ipython. +label_flag( + name = "repl_stub_dep", + build_setting_default = "//python/private:empty", +) + +# The user can modify this flag to make arbitrary PyInfo targets available for +# import on the REPL. +label_flag( + name = "repl_dep", + build_setting_default = "//python/private:empty", +) diff --git a/python/bin/repl_stub.py b/python/bin/repl_stub.py new file mode 100644 index 0000000000..86452aa869 --- /dev/null +++ b/python/bin/repl_stub.py @@ -0,0 +1,29 @@ +"""Simulates the REPL that Python spawns when invoking the binary with no arguments. + +The code module is responsible for the default shell. + +The import and `ocde.interact()` call here his is equivalent to doing: + + $ python3 -m code + Python 3.11.2 (main, Mar 13 2023, 12:18:29) [GCC 12.2.0] on linux + Type "help", "copyright", "credits" or "license" for more information. + (InteractiveConsole) + >>> + +The logic for PYTHONSTARTUP is handled in python/private/repl_template.py. +""" + +import code +import sys + +if sys.stdin.isatty(): + # Use the default options. + exitmsg = None +else: + # On a non-interactive console, we want to suppress the >>> and the exit message. + exitmsg = "" + sys.ps1 = "" + sys.ps2 = "" + +# We set the banner to an empty string because the repl_template.py file already prints the banner. +code.interact(banner="", exitmsg=exitmsg) diff --git a/python/private/BUILD.bazel b/python/private/BUILD.bazel index e72a8fcaa7..212ff0546c 100644 --- a/python/private/BUILD.bazel +++ b/python/private/BUILD.bazel @@ -822,6 +822,10 @@ current_interpreter_executable( visibility = ["//visibility:public"], ) +py_library( + name = "empty", +) + sentinel( name = "sentinel", ) diff --git a/python/private/repl.bzl b/python/private/repl.bzl new file mode 100644 index 0000000000..838166a187 --- /dev/null +++ b/python/private/repl.bzl @@ -0,0 +1,84 @@ +"""Implementation of the rules to expose a REPL.""" + +load("//python:py_binary.bzl", _py_binary = "py_binary") + +def _generate_repl_main_impl(ctx): + stub_repo = ctx.attr.stub.label.repo_name or ctx.workspace_name + stub_path = "/".join([stub_repo, ctx.file.stub.short_path]) + + out = ctx.actions.declare_file(ctx.label.name + ".py") + + # Point the generated main file at the stub. + ctx.actions.expand_template( + template = ctx.file._template, + output = out, + substitutions = { + "%stub_path%": stub_path, + }, + ) + + return [DefaultInfo(files = depset([out]))] + +_generate_repl_main = rule( + implementation = _generate_repl_main_impl, + attrs = { + "stub": attr.label( + mandatory = True, + allow_single_file = True, + doc = ("The stub responsible for actually invoking the final shell. " + + "See the \"Customizing the REPL\" docs for details."), + ), + "_template": attr.label( + default = "//python/private:repl_template.py", + allow_single_file = True, + doc = "The template to use for generating `out`.", + ), + }, + doc = """\ +Generates a "main" script for a py_binary target that starts a Python REPL. + +The template is designed to take care of the majority of the logic. The user +customizes the exact shell that will be started via the stub. The stub is a +simple shell script that imports the desired shell and then executes it. + +The target's name is used for the output filename (with a .py extension). +""", +) + +def py_repl_binary(name, stub, deps = [], data = [], **kwargs): + """A py_binary target that executes a REPL when run. + + The stub is the script that ultimately decides which shell the REPL will run. + It can be as simple as this: + + import code + code.interact() + + Or it can load something like IPython instead. + + Args: + name: Name of the generated py_binary target. + stub: The script that invokes the shell. + deps: The dependencies of the py_binary. + data: The runtime dependencies of the py_binary. + **kwargs: Forwarded to the py_binary. + """ + _generate_repl_main( + name = "%s_py" % name, + stub = stub, + ) + + _py_binary( + name = name, + srcs = [ + ":%s_py" % name, + ], + main = "%s_py.py" % name, + data = data + [ + stub, + ], + deps = deps + [ + "//python/runfiles", + ], + **kwargs + ) diff --git a/python/private/repl_template.py b/python/private/repl_template.py new file mode 100644 index 0000000000..0e058b23ae --- /dev/null +++ b/python/private/repl_template.py @@ -0,0 +1,37 @@ +import os +import runpy +import sys +from pathlib import Path + +from python.runfiles import runfiles + +STUB_PATH = "%stub_path%" + + +def start_repl(): + if sys.stdin.isatty(): + # Print the banner similar to how python does it on startup when running interactively. + cprt = 'Type "help", "copyright", "credits" or "license" for more information.' + sys.stderr.write("Python %s on %s\n%s\n" % (sys.version, sys.platform, cprt)) + + # Simulate Python's behavior when a valid startup script is defined by the + # PYTHONSTARTUP variable. If this file path fails to load, print the error + # and revert to the default behavior. + # + # See upstream for more information: + # https://docs.python.org/3/using/cmdline.html#envvar-PYTHONSTARTUP + if startup_file := os.getenv("PYTHONSTARTUP"): + try: + source_code = Path(startup_file).read_text() + except Exception as error: + print(f"{type(error).__name__}: {error}") + else: + compiled_code = compile(source_code, filename=startup_file, mode="exec") + eval(compiled_code, {}) + + bazel_runfiles = runfiles.Create() + runpy.run_path(bazel_runfiles.Rlocation(STUB_PATH), run_name="__main__") + + +if __name__ == "__main__": + start_repl() diff --git a/tests/repl/BUILD.bazel b/tests/repl/BUILD.bazel new file mode 100644 index 0000000000..62c7377d53 --- /dev/null +++ b/tests/repl/BUILD.bazel @@ -0,0 +1,44 @@ +load("//python:py_library.bzl", "py_library") +load("//tests/support:sh_py_run_test.bzl", "py_reconfig_test") + +# A library that adds a special import path only when this is specified as a +# dependency. This makes it easy for a dependency to have this import path +# available without the top-level target being able to import the module. +py_library( + name = "helper/test_module", + srcs = [ + "helper/test_module.py", + ], + imports = [ + "helper", + ], +) + +py_reconfig_test( + name = "repl_without_dep_test", + srcs = ["repl_test.py"], + data = [ + "//python/bin:repl", + ], + env = { + # The helper/test_module should _not_ be importable for this test. + "EXPECT_TEST_MODULE_IMPORTABLE": "0", + }, + main = "repl_test.py", + python_version = "3.12", +) + +py_reconfig_test( + name = "repl_with_dep_test", + srcs = ["repl_test.py"], + data = [ + "//python/bin:repl", + ], + env = { + # The helper/test_module _should_ be importable for this test. + "EXPECT_TEST_MODULE_IMPORTABLE": "1", + }, + main = "repl_test.py", + python_version = "3.12", + repl_dep = ":helper/test_module", +) diff --git a/tests/repl/helper/test_module.py b/tests/repl/helper/test_module.py new file mode 100644 index 0000000000..0c4a309b01 --- /dev/null +++ b/tests/repl/helper/test_module.py @@ -0,0 +1,5 @@ +"""This is a file purely intended for validating //python/bin:repl.""" + + +def print_hello(): + print("Hello World") diff --git a/tests/repl/repl_test.py b/tests/repl/repl_test.py new file mode 100644 index 0000000000..51ca951110 --- /dev/null +++ b/tests/repl/repl_test.py @@ -0,0 +1,74 @@ +import os +import subprocess +import sys +import unittest +from typing import Iterable + +from python import runfiles + +rfiles = runfiles.Create() + +# Signals the tests below whether we should be expecting the import of +# helpers/test_module.py on the REPL to work or not. +EXPECT_TEST_MODULE_IMPORTABLE = os.environ["EXPECT_TEST_MODULE_IMPORTABLE"] == "1" + + +class ReplTest(unittest.TestCase): + def setUp(self): + self.repl = rfiles.Rlocation("rules_python/python/bin/repl") + assert self.repl + + def run_code_in_repl(self, lines: Iterable[str]) -> str: + """Runs the lines of code in the REPL and returns the text output.""" + return subprocess.check_output( + [self.repl], + text=True, + stderr=subprocess.STDOUT, + input="\n".join(lines), + ).strip() + + def test_repl_version(self): + """Validates that we can successfully execute arbitrary code on the REPL.""" + + result = self.run_code_in_repl( + [ + "import sys", + "v = sys.version_info", + "print(f'version: {v.major}.{v.minor}')", + ] + ) + self.assertIn("version: 3.12", result) + + def test_cannot_import_test_module_directly(self): + """Validates that we cannot import helper/test_module.py since it's not a direct dep.""" + with self.assertRaises(ModuleNotFoundError): + import test_module + + @unittest.skipIf( + not EXPECT_TEST_MODULE_IMPORTABLE, "test only works without repl_dep set" + ) + def test_import_test_module_success(self): + """Validates that we can import helper/test_module.py when repl_dep is set.""" + result = self.run_code_in_repl( + [ + "import test_module", + "test_module.print_hello()", + ] + ) + self.assertIn("Hello World", result) + + @unittest.skipIf( + EXPECT_TEST_MODULE_IMPORTABLE, "test only works without repl_dep set" + ) + def test_import_test_module_failure(self): + """Validates that we cannot import helper/test_module.py when repl_dep isn't set.""" + result = self.run_code_in_repl( + [ + "import test_module", + ] + ) + self.assertIn("ModuleNotFoundError: No module named 'test_module'", result) + + +if __name__ == "__main__": + unittest.main() diff --git a/tests/support/sh_py_run_test.bzl b/tests/support/sh_py_run_test.bzl index 9c8134ff40..f6ebc506cc 100644 --- a/tests/support/sh_py_run_test.bzl +++ b/tests/support/sh_py_run_test.bzl @@ -38,6 +38,8 @@ def _perform_transition_impl(input_settings, attr, base_impl): settings["//command_line_option:extra_toolchains"] = attr.extra_toolchains if attr.python_src: settings["//python/bin:python_src"] = attr.python_src + if attr.repl_dep: + settings["//python/bin:repl_dep"] = attr.repl_dep if attr.venvs_use_declare_symlink: settings["//python/config_settings:venvs_use_declare_symlink"] = attr.venvs_use_declare_symlink if attr.venvs_site_packages: @@ -47,6 +49,7 @@ def _perform_transition_impl(input_settings, attr, base_impl): _RECONFIG_INPUTS = [ "//python/config_settings:bootstrap_impl", "//python/bin:python_src", + "//python/bin:repl_dep", "//command_line_option:extra_toolchains", "//python/config_settings:venvs_use_declare_symlink", "//python/config_settings:venvs_site_packages", @@ -70,6 +73,7 @@ toolchain. """, ), "python_src": attrb.Label(), + "repl_dep": attrb.Label(), "venvs_site_packages": attrb.String(), "venvs_use_declare_symlink": attrb.String(), }