docs: make readthedocs render a bit nicer and port docs over to Sphinx (bazel-contrib#1511)

This makes the Sphinx-based docs hosted on readthedocs render a bit more
nicely, fixes a few issues, and adds some features to //sphinxdocs

This also moves all the docs onto Sphinx, deleting the checked-in
documentation.

Doc fixes/improvements:
* Ports various docs over to Sphinx pages. They're split out from the
readme file.
* Version RTD is building is reflected in the docs
* Fixes some references to github files
* Includes the custom CSS file that styled the api docs
* Removes `-Q` from doc building; all warnings should be fixed now
* Added Bazel inventory file. Bazel doesn't provide one, but we can
manually provide on
  and still use intersphinx functionality.
* Added `gh-path` custom role. This is a shortcut for writing the whole
github URL.
* Sets the primary domain to None. The default is py, which we don't use
much of, so it
  just results in confusing crossref errors.
* Enable nitpicky mode to catch more errors.
* Remove the `starlark` marker from codeblocks; that name isn't
recognized by Sphinx.
  The highlighting is still sufficient.
* Adds a glossary

Sphinxdocs improvements:
* Added a flag to pass along arbitrary `-D` args to the Sphinx
invocations. This allows
e.g., the `version` setting of the docs to be set on the command line
from the
  `READTHEDOCS_VERSION` environment variable
* Added inventory file generation. These are files that allow
referencing external
  projects using intersphinx.
* `sphinx_stardocs` have their public load path set as their page title.
This groups the
  API docs more naturally by file. The path can be customized.
* `sphinx_stardocs` can have a footer specified for generated pages.
This allows easily
  added a list of link labels for easy re-use.
* `readthedocs_install` now tries harder to find an open port
* The conf.py file is moved into the generated sources directly. This
was done because some
config settings are relative to the conf.py file, which was being placed
one directory
  above the regular sources.

Fixes bazel-contrib#1484, bazel-contrib#1481

Author: rickeylev

.bazelrc

@@ -23,3 +23,7 @@ startup --windows_enable_symlinks
 # TODO: migrate all dependencies from WORKSPACE to MODULE.bazel
 # https://github.com/bazelbuild/rules_python/issues/1469
 common --noexperimental_enable_bzlmod
+
+# Additional config to use for readthedocs builds.
+# See .readthedocs.yml for additional flags
+build:rtd --stamp

.readthedocs.yml

@@ -6,5 +6,6 @@ build:
   tools:
     nodejs: "19"
   commands:
+    - env
     - npm install -g @bazel/bazelisk
-    - bazel run //docs/sphinx:readthedocs_install
+    - bazel run --config=rtd --//sphinxdocs:extra_defines=version=$READTHEDOCS_VERSION //docs/sphinx:readthedocs_install

README.md

@@ -8,9 +8,7 @@ This repository is the home of the core Python rules -- `py_library`,
 `py_binary`, `py_test`, `py_proto_library`, and related symbols that provide the basis for Python
 support in Bazel. It also contains package installation rules for integrating with PyPI and other indices. 
 
-Documentation for rules_python  lives in the
-[`docs/`](https://github.com/bazelbuild/rules_python/tree/main/docs)
-directory and in the
+Documentation for rules_python is at <https://rules-python.readthedocs.io> and in the
 [Bazel Build Encyclopedia](https://docs.bazel.build/versions/master/be/python.html).
 
 Examples live in the [examples](examples) directory.
@@ -25,356 +23,13 @@ rate, but this repository will still follow [semantic versioning](https://semver
 
 The Bazel community maintains this repository. Neither Google nor the Bazel team provides support for the code. However, this repository is part of the test suite used to vet new Bazel releases. See [How to contribute](CONTRIBUTING.md) page for information on our development workflow.
 
+## Documentation
+
+For detailed documentation, see <https://rules-python.readthedocs.io>
+
 ## Bzlmod support
 
 - Status: Beta
 - Full Feature Parity: No
 
 See [Bzlmod support](BZLMOD_SUPPORT.md) for more details.
-
-## Getting started
-
-The following two sections cover using `rules_python` with bzlmod and
-the older way of configuring bazel with a `WORKSPACE` file.
-
-### Using bzlmod
-
-**IMPORTANT: bzlmod support is still in Beta; APIs are subject to change.**
-
-The first step to using rules_python with bzlmod is to add the dependency to
-your MODULE.bazel file:
-
-```starlark
-# Update the version "0.0.0" to the release found here:
-# https://github.com/bazelbuild/rules_python/releases.
-bazel_dep(name = "rules_python", version = "0.0.0")
-```
-
-Once added, you can load the rules and use them:
-
-```starlark
-load("@rules_python//python:py_binary.bzl", "py_binary")
-
-py_binary(...)
-```
-
-Depending on what you're doing, you likely want to do some additional
-configuration to control what Python version is used; read the following
-sections for how to do that.
-
-#### Toolchain registration with bzlmod
-
-A default toolchain is automatically configured depending on
-`rules_python`. Note, however, the version used tracks the most recent Python
-release and will change often.
-
-If you want to use a specific Python version for your programs, then how
-to do so depends on if you're configuring the root module or not. The root
-module is special because it can set the *default* Python version, which
-is used by the version-unaware rules (e.g. `//python:py_binary.bzl` et al). For
-submodules, it's recommended to use the version-aware rules to pin your programs
-to a specific Python version so they don't accidentally run with a different
-version configured by the root module.
-
-##### Configuring and using the default Python version
-
-To specify what the default Python version is, set `is_default = True` when
-calling `python.toolchain()`. This can only be done by the root module; it is
-silently ignored if a submodule does it. Similarly, using the version-unaware
-rules (which always use the default Python version) should only be done by the
-root module. If submodules use them, then they may run with a different Python
-version than they expect.
-
-```starlark
-python = use_extension("@rules_python//python/extensions:python.bzl", "python")
-
-python.toolchain(
-    python_version = "3.11",
-    is_default = True,
-)
-```
-
-Then use the base rules from e.g. `//python:py_binary.bzl`.
-
-##### Pinning to a Python version
-
-Pinning to a version allows targets to force that a specific Python version is
-used, even if the root module configures a different version as a default. This
-is most useful for two cases:
-
-1. For submodules to ensure they run with the appropriate Python version
-2. To allow incremental, per-target, upgrading to newer Python versions,
-   typically in a mono-repo situation.
-
-To configure a submodule with the version-aware rules, request the particular
-version you need, then use the `@python_versions` repo to use the rules that
-force specific versions:
-
-```starlark
-python = use_extension("@rules_python//python/extensions:python.bzl", "python")
-
-python.toolchain(
-    python_version = "3.11",
-)
-use_repo(python, "python_versions")
-```
-
-Then use e.g. `load("@python_versions//3.11:defs.bzl", "py_binary")` to use
-the rules that force that particular version. Multiple versions can be specified
-and use within a single build.
-
-For more documentation, see the bzlmod examples under the [examples](examples) folder.  Look for the examples that contain a `MODULE.bazel` file.
-
-##### Other toolchain details
-
-The `python.toolchain()` call makes its contents available under a repo named
-`python_X_Y`, where X and Y are the major and minor versions. For example,
-`python.toolchain(python_version="3.11")` creates the repo `@python_3_11`.
-Remember to call `use_repo()` to make repos visible to your module:
-`use_repo(python, "python_3_11")`
-
-### Using a WORKSPACE file
-
-To import rules_python in your project, you first need to add it to your
-`WORKSPACE` file, using the snippet provided in the
-[release you choose](https://github.com/bazelbuild/rules_python/releases)
-
-To depend on a particular unreleased version, you can do the following:
-
-```starlark
-load("@bazel_tools//tools/build_defs/repo:http.bzl", "http_archive")
-
-
-# Update the SHA and VERSION to the lastest version available here:
-# https://github.com/bazelbuild/rules_python/releases.
-
-SHA="84aec9e21cc56fbc7f1335035a71c850d1b9b5cc6ff497306f84cced9a769841"
-
-VERSION="0.23.1"
-
-http_archive(
-    name = "rules_python",
-    sha256 = SHA,
-    strip_prefix = "rules_python-{}".format(VERSION),
-    url = "https://github.com/bazelbuild/rules_python/releases/download/{}/rules_python-{}.tar.gz".format(VERSION,VERSION),
-)
-
-load("@rules_python//python:repositories.bzl", "py_repositories")
-
-py_repositories()
-```
-
-#### Toolchain registration
-
-To register a hermetic Python toolchain rather than rely on a system-installed interpreter for runtime execution, you can add to the `WORKSPACE` file:
-
-```starlark
-load("@rules_python//python:repositories.bzl", "python_register_toolchains")
-
-python_register_toolchains(
-    name = "python_3_11",
-    # Available versions are listed in @rules_python//python:versions.bzl.
-    # We recommend using the same version your team is already standardized on.
-    python_version = "3.11",
-)
-
-load("@python_3_11//:defs.bzl", "interpreter")
-
-load("@rules_python//python:pip.bzl", "pip_parse")
-
-pip_parse(
-    ...
-    python_interpreter_target = interpreter,
-    ...
-)
-```
-
-After registration, your Python targets will use the toolchain's interpreter during execution, but a system-installed interpreter
-is still used to 'bootstrap' Python targets (see https://github.com/bazelbuild/rules_python/issues/691).
-You may also find some quirks while using this toolchain. Please refer to [python-build-standalone documentation's _Quirks_ section](https://python-build-standalone.readthedocs.io/en/latest/quirks.html).
-
-### Toolchain usage in other rules
-
-Python toolchains can be utilized in other bazel rules, such as `genrule()`, by adding the `toolchains=["@rules_python//python:current_py_toolchain"]` attribute. You can obtain the path to the Python interpreter using the `$(PYTHON2)` and `$(PYTHON3)` ["Make" Variables](https://bazel.build/reference/be/make-variables). See the [`test_current_py_toolchain`](tests/load_from_macro/BUILD.bazel) target for an example.
-
-### "Hello World"
-
-Once you've imported the rule set into your `WORKSPACE` using any of these
-methods, you can then load the core rules in your `BUILD` files with the following:
-
-```starlark
-load("@rules_python//python:defs.bzl", "py_binary")
-
-py_binary(
-  name = "main",
-  srcs = ["main.py"],
-)
-```
-
-## Using dependencies from PyPI
-
-Using PyPI packages (aka "pip install") involves two main steps.
-
-1. [Installing third_party packages](#installing-third_party-packages)
-2. [Using third_party packages as dependencies](#using-third_party-packages-as-dependencies)
-
-### Installing third_party packages
-
-#### Using bzlmod
-
-To add pip dependencies to your `MODULE.bazel` file, use the `pip.parse` extension, and call it to create the central external repo and individual wheel external repos. Include in the `MODULE.bazel` the toolchain extension as shown in the first bzlmod example above.
-
-```starlark
-pip = use_extension("@rules_python//python/extensions:pip.bzl", "pip")
-pip.parse(
-    hub_name = "my_deps",
-    python_version = "3.11",
-    requirements_lock = "//:requirements_lock_3_11.txt",
-)
-use_repo(pip, "my_deps")
-```
-For more documentation, including how the rules can update/create a requirements file, see the bzlmod examples under the [examples](examples) folder.
-
-#### Using a WORKSPACE file
-
-To add pip dependencies to your `WORKSPACE`, load the `pip_parse` function and call it to create the central external repo and individual wheel external repos.
-
-```starlark
-load("@rules_python//python:pip.bzl", "pip_parse")
-
-# Create a central repo that knows about the dependencies needed from
-# requirements_lock.txt.
-pip_parse(
-   name = "my_deps",
-   requirements_lock = "//path/to:requirements_lock.txt",
-)
-# Load the starlark macro, which will define your dependencies.
-load("@my_deps//:requirements.bzl", "install_deps")
-# Call it to define repos for your requirements.
-install_deps()
-```
-
-#### pip rules
-
-Note that since `pip_parse` is a repository rule and therefore executes pip at WORKSPACE-evaluation time, Bazel has no
-information about the Python toolchain and cannot enforce that the interpreter
-used to invoke pip matches the interpreter used to run `py_binary` targets. By
-default, `pip_parse` uses the system command `"python3"`. To override this, pass in the
-`python_interpreter` attribute or `python_interpreter_target` attribute to `pip_parse`.
-
-You can have multiple `pip_parse`s in the same workspace.  Or use the pip extension multiple times when using bzlmod.
-This configuration will create multiple external repos that have no relation to one another 
-and may result in downloading the same wheels numerous times.
-
-As with any repository rule, if you would like to ensure that `pip_parse` is
-re-executed to pick up a non-hermetic change to your environment (e.g.,
-updating your system `python` interpreter), you can force it to re-execute by running
-`bazel sync --only [pip_parse name]`.
-
-Note: The `pip_install` rule is deprecated. `pip_parse` offers identical functionality, and both `pip_install` and `pip_parse` now have the same implementation. The name `pip_install` may be removed in a future version of the rules.
-
-The maintainers have made all reasonable efforts to facilitate a smooth transition. Still, some users of `pip_install` will need to replace their existing `requirements.txt` with a fully resolved set of dependencies using a tool such as `pip-tools` or the `compile_pip_requirements` repository rule.
-
-### Using third_party packages as dependencies
-
-Each extracted wheel repo contains a `py_library` target representing
-the wheel's contents. There are two ways to access this library. The
-first uses the `requirement()` function defined in the central
-repo's `//:requirements.bzl` file. This function maps a pip package
-name to a label:
-
-```starlark
-load("@my_deps//:requirements.bzl", "requirement")
-
-py_library(
-    name = "mylib",
-    srcs = ["mylib.py"],
-    deps = [
-        ":myotherlib",
-        requirement("some_pip_dep"),
-        requirement("another_pip_dep"),
-    ]
-)
-```
-
-The reason `requirement()` exists is that the pattern for the labels,
-while not expected to change frequently, is not guaranteed to be
-stable. Using `requirement()` ensures you do not have to refactor
-your `BUILD` files if the pattern changes.
-
-On the other hand, using `requirement()` has several drawbacks; see
-[this issue][requirements-drawbacks] for an enumeration. If you don't
-want to use `requirement()`, you can use the library
-labels directly instead. For `pip_parse`, the labels are of the following form:
-
-```starlark
-@{name}_{package}//:pkg
-```
-
-Here `name` is the `name` attribute that was passed to `pip_parse` and
-`package` is the pip package name with characters that are illegal in
-Bazel label names (e.g. `-`, `.`) replaced with `_`. If you need to
-update `name` from "old" to "new", then you can run the following
-buildozer command:
-
-```shell
-buildozer 'substitute deps @old_([^/]+)//:pkg @new_${1}//:pkg' //...:*
-```
-
-For `pip_install`, the labels are instead of the form:
-
-```starlark
-@{name}//pypi__{package}
-```
-
-[requirements-drawbacks]: https://github.com/bazelbuild/rules_python/issues/414
-
-#### 'Extras' dependencies
-
-Any 'extras' specified in the requirements lock file will be automatically added as transitive dependencies of the package. In the example above, you'd just put `requirement("useful_dep")`.
-
-### Consuming Wheel Dists Directly
-
-If you need to depend on the wheel dists themselves, for instance, to pass them
-to some other packaging tool, you can get a handle to them with the `whl_requirement` macro. For example:
-
-```starlark
-filegroup(
-    name = "whl_files",
-    data = [
-        whl_requirement("boto3"),
-    ]
-)
-```
-# Python Gazelle plugin
-
-[Gazelle](https://github.com/bazelbuild/bazel-gazelle)
-is a build file generator for Bazel projects. It can create new `BUILD.bazel` files for a project that follows language conventions and update existing build files to include new sources, dependencies, and options.
-
-Bazel may run Gazelle using the Gazelle rule, or it may be installed and run as a command line tool.
-
-See the documentation for Gazelle with rules_python [here](gazelle).
-
-## Migrating from the bundled rules
-
-The core rules are currently available in Bazel as built-in symbols, but this
-form is deprecated. Instead, you should depend on rules_python in your
-`WORKSPACE` file and load the Python rules from
-`@rules_python//python:defs.bzl`.
-
-A [buildifier](https://github.com/bazelbuild/buildtools/blob/master/buildifier/README.md)
-fix is available to automatically migrate `BUILD` and `.bzl` files to add the
-appropriate `load()` statements and rewrite uses of `native.py_*`.
-
-```sh
-# Also consider using the -r flag to modify an entire workspace.
-buildifier --lint=fix --warnings=native-py <files>
-```
-
-Currently, the `WORKSPACE` file needs to be updated manually as per [Getting
-started](#Getting-started) above.
-
-Note that Starlark-defined bundled symbols underneath
-`@bazel_tools//tools/python` are also deprecated. These are not yet rewritten
-by buildifier.
-