diff --git a/.bazelci/presubmit.yml b/.bazelci/presubmit.yml index 3b70734eff..7e9d4dea53 100644 --- a/.bazelci/presubmit.yml +++ b/.bazelci/presubmit.yml @@ -51,9 +51,11 @@ buildifier: test_flags: - "--noenable_bzlmod" - "--enable_workspace" + - "--test_tag_filters=-integration-test" build_flags: - "--noenable_bzlmod" - "--enable_workspace" + - "--build_tag_filters=-integration-test" bazel: 7.x .common_bazelinbazel_config: &common_bazelinbazel_config build_flags: diff --git a/CHANGELOG.md b/CHANGELOG.md index 17e3cd3c86..d9cb14459d 100644 --- a/CHANGELOG.md +++ b/CHANGELOG.md @@ -84,6 +84,8 @@ END_UNRELEASED_TEMPLATE * Repo utilities `execute_unchecked`, `execute_checked`, and `execute_checked_stdout` now support `log_stdout` and `log_stderr` keyword arg booleans. When these are `True` (the default), the subprocess's stdout/stderr will be logged. +* (toolchains) Local toolchains can be activated with custom flags. See + [Conditionally using local toolchains] docs for how to configure. {#v0-0-0-removed} ### Removed diff --git a/docs/toolchains.md b/docs/toolchains.md index 2f8db66595..c8305e8f0d 100644 --- a/docs/toolchains.md +++ b/docs/toolchains.md @@ -377,15 +377,14 @@ local_runtime_repo( local_runtime_toolchains_repo( name = "local_toolchains", runtimes = ["local_python3"], + # TIP: The `target_settings` arg can be used to activate them based on + # command line flags; see docs below. ) # Step 3: Register the toolchains register_toolchains("@local_toolchains//:all", dev_dependency = True) ``` -Note that `register_toolchains` will insert the local toolchain earlier in the -toolchain ordering, so it will take precedence over other registered toolchains. - :::{important} Be sure to set `dev_dependency = True`. Using a local toolchain only makes sense for the root module. @@ -397,6 +396,72 @@ downstream modules. Multiple runtimes and/or toolchains can be defined, which allows for multiple Python versions and/or platforms to be configured in a single `MODULE.bazel`. +Note that `register_toolchains` will insert the local toolchain earlier in the +toolchain ordering, so it will take precedence over other registered toolchains. +To better control when the toolchain is used, see [Conditionally using local +toolchains] + +### Conditionally using local toolchains + +By default, a local toolchain has few constraints and is early in the toolchain +ordering, which means it will usually be used no matter what. This can be +problematic for CI (where it shouldn't be used), expensive for CI (CI must +initialize/download the repository to determine its Python version), and +annoying for iterative development (enabling/disabling it requires modifying +MODULE.bazel). + +These behaviors can be mitigated, but it requires additional configuration +to avoid triggering the local toolchain repository to initialize (i.e. run +local commands and perform downloads). + +The two settings to change are +{obj}`local_runtime_toolchains_repo.target_compatible_with` and +{obj}`local_runtime_toolchains_repo.target_settings`, which control how Bazel +decides if a toolchain should match. By default, they point to targets *within* +the local runtime repository (trigger repo initialization). We have to override +them to *not* reference the local runtime repository at all. + +In the example below, we reconfigure the local toolchains so they are only +activated if the custom flag `--//:py=local` is set and the target platform +matches the Bazel host platform. The net effect is CI won't use the local +toolchain (nor initialize its repository), and developers can easily +enable/disable the local toolchain with a command line flag. + +``` +# File: MODULE.bazel +bazel_dep(name = "bazel_skylib", version = "1.7.1") + +local_runtime_toolchains_repo( + name = "local_toolchains", + runtimes = ["local_python3"], + target_compatible_with = { + "local_python3": ["HOST_CONSTRAINTS"], + }, + target_settings = { + "local_python3": ["@//:is_py_local"] + } +) + +# File: BUILD.bazel +load("@bazel_skylib//rules:common_settings.bzl", "string_flag") + +config_setting( + name = "is_py_local", + flag_values = {":py": "local"}, +) + +string_flag( + name = "py", + build_setting_default = "", +) +``` + +:::{tip} +Easily switching between *multiple* local toolchains can be accomplished by +adding additional `:is_py_X` targets and setting `--//:py` to match. +to easily switch between different local toolchains. +::: + ## Runtime environment toolchain @@ -425,7 +490,7 @@ locally installed Python. ### Autodetecting toolchain The autodetecting toolchain is a deprecated toolchain that is built into Bazel. -It's name is a bit misleading: it doesn't autodetect anything. All it does is +**It's name is a bit misleading: it doesn't autodetect anything**. All it does is use `python3` from the environment a binary runs within. This provides extremely limited functionality to the rules (at build time, nothing is knowable about the Python runtime). diff --git a/python/private/local_runtime_toolchains_repo.bzl b/python/private/local_runtime_toolchains_repo.bzl index adb3bb560d..004ca664ad 100644 --- a/python/private/local_runtime_toolchains_repo.bzl +++ b/python/private/local_runtime_toolchains_repo.bzl @@ -26,6 +26,9 @@ define_local_toolchain_suites( name = "toolchains", version_aware_repo_names = {version_aware_names}, version_unaware_repo_names = {version_unaware_names}, + repo_exec_compatible_with = {repo_exec_compatible_with}, + repo_target_compatible_with = {repo_target_compatible_with}, + repo_target_settings = {repo_target_settings}, ) """ @@ -39,6 +42,9 @@ def _local_runtime_toolchains_repo(rctx): rctx.file("BUILD.bazel", _TOOLCHAIN_TEMPLATE.format( version_aware_names = render.list(rctx.attr.runtimes), + repo_target_settings = render.string_list_dict(rctx.attr.target_settings), + repo_target_compatible_with = render.string_list_dict(rctx.attr.target_compatible_with), + repo_exec_compatible_with = render.string_list_dict(rctx.attr.exec_compatible_with), version_unaware_names = render.list(rctx.attr.default_runtimes or rctx.attr.runtimes), )) @@ -62,8 +68,36 @@ These will be defined as *version-unaware* toolchains. This means they will match any Python version. As such, they are registered after the version-aware toolchains defined by the `runtimes` attribute. +If not set, then the `runtimes` values will be used. + Note that order matters: it determines the toolchain priority within the package. +""", + ), + "exec_compatible_with": attr.string_list_dict( + doc = """ +Constraints that must be satisfied by an exec platform for a toolchain to be used. + +This is a `dict[str, list[str]]`, where the keys are repo names from the +`runtimes` or `default_runtimes` args, and the values are constraint +target labels (e.g. OS, CPU, etc). + +:::{note} +Specify `@//foo:bar`, not simply `//foo:bar` or `:bar`. The additional `@` is +needed because the strings are evaluated in a different context than where +they originate. +::: + +The list of settings become the {obj}`toolchain.exec_compatible_with` value for +each respective repo. + +This allows a local toolchain to only be used if certain exec platform +conditions are met, typically values from `@platforms`. + +See the [Local toolchains] docs for examples and further information. + +:::{versionadded} VERSION_NEXT_FEATURE +::: """, ), "runtimes": attr.string_list( @@ -76,6 +110,81 @@ are registered before `default_runtimes`. Note that order matters: it determines the toolchain priority within the package. +""", + ), + "target_compatible_with": attr.string_list_dict( + doc = """ +Constraints that must be satisfied for a toolchain to be used. + + +This is a `dict[str, list[str]]`, where the keys are repo names from the +`runtimes` or `default_runtimes` args, and the values are constraint +target labels (e.g. OS, CPU, etc), or the special string `"HOST_CONSTRAINTS"` +(which will be replaced with the current Bazel hosts's constraints). + +If a repo's entry is missing or empty, it defaults to the supported OS the +underlying runtime repository detects as compatible. + +:::{note} +Specify `@//foo:bar`, not simply `//foo:bar` or `:bar`. The additional `@` is +needed because the strings are evaluated in a different context than where +they originate. +::: + +The list of settings **becomes the** the {obj}`toolchain.target_compatible_with` +value for each respective repo; i.e. they _replace_ the auto-detected values +the local runtime itself computes. + +This allows a local toolchain to only be used if certain target platform +conditions are met, typically values from `@platforms`. + +See the [Local toolchains] docs for examples and further information. + +:::{seealso} +The `target_settings` attribute, which handles `config_setting` values, +instead of constraints. +::: + +:::{versionadded} VERSION_NEXT_FEATURE +::: +""", + ), + "target_settings": attr.string_list_dict( + doc = """ +Config settings that must be satisfied for a toolchain to be used. + +This is a `dict[str, list[str]]`, where the keys are repo names from the +`runtimes` or `default_runtimes` args, and the values are {obj}`config_setting()` +target labels. + +If a repo's entry is missing or empty, it will default to +`@//:is_match_python_version` (for repos in `runtimes`) or an empty list +(for repos in `default_runtimes`). + +:::{note} +Specify `@//foo:bar`, not simply `//foo:bar` or `:bar`. The additional `@` is +needed because the strings are evaluated in a different context than where +they originate. +::: + +The list of settings will be applied atop of any of the local runtime's +settings that are used for {obj}`toolchain.target_settings`. i.e. they are +evaluated first and guard the checking of the local runtime's auto-detected +conditions. + +This allows a local toolchain to only be used if certain flags or +config setting conditions are met. Such conditions can include user-defined +flags, platform constraints, etc. + +See the [Local toolchains] docs for examples and further information. + +:::{seealso} +The `target_compatible_with` attribute, which handles *constraint* values, +instead of `config_settings`. +::: + +:::{versionadded} VERSION_NEXT_FEATURE +::: """, ), "_rule_name": attr.string(default = "local_toolchains_repo"), diff --git a/python/private/py_toolchain_suite.bzl b/python/private/py_toolchain_suite.bzl index a69be376b4..e71882dafd 100644 --- a/python/private/py_toolchain_suite.bzl +++ b/python/private/py_toolchain_suite.bzl @@ -15,6 +15,7 @@ """Create the toolchain defs in a BUILD.bazel file.""" load("@bazel_skylib//lib:selects.bzl", "selects") +load("@platforms//host:constraints.bzl", "HOST_CONSTRAINTS") load(":text_util.bzl", "render") load( ":toolchain_types.bzl", @@ -95,9 +96,15 @@ def py_toolchain_suite( runtime_repo_name = user_repository_name, target_settings = target_settings, target_compatible_with = target_compatible_with, + exec_compatible_with = [], ) -def _internal_toolchain_suite(prefix, runtime_repo_name, target_compatible_with, target_settings): +def _internal_toolchain_suite( + prefix, + runtime_repo_name, + target_compatible_with, + target_settings, + exec_compatible_with): native.toolchain( name = "{prefix}_toolchain".format(prefix = prefix), toolchain = "@{runtime_repo_name}//:python_runtimes".format( @@ -106,6 +113,7 @@ def _internal_toolchain_suite(prefix, runtime_repo_name, target_compatible_with, toolchain_type = TARGET_TOOLCHAIN_TYPE, target_settings = target_settings, target_compatible_with = target_compatible_with, + exec_compatible_with = exec_compatible_with, ) native.toolchain( @@ -116,6 +124,7 @@ def _internal_toolchain_suite(prefix, runtime_repo_name, target_compatible_with, toolchain_type = PY_CC_TOOLCHAIN_TYPE, target_settings = target_settings, target_compatible_with = target_compatible_with, + exec_compatible_with = exec_compatible_with, ) native.toolchain( @@ -142,7 +151,13 @@ def _internal_toolchain_suite(prefix, runtime_repo_name, target_compatible_with, # call in python/repositories.bzl. Bzlmod doesn't need anything; it will # register `:all`. -def define_local_toolchain_suites(name, version_aware_repo_names, version_unaware_repo_names): +def define_local_toolchain_suites( + name, + version_aware_repo_names, + version_unaware_repo_names, + repo_exec_compatible_with, + repo_target_compatible_with, + repo_target_settings): """Define toolchains for `local_runtime_repo` backed toolchains. This generates `toolchain` targets that can be registered using `:all`. The @@ -156,24 +171,60 @@ def define_local_toolchain_suites(name, version_aware_repo_names, version_unawar version-aware toolchains defined. version_unaware_repo_names: `list[str]` of the repo names that will have version-unaware toolchains defined. + repo_target_settings: {type}`dict[str, list[str]]` mapping of repo names + to string labels that are added to the `target_settings` for the + respective repo's toolchain. + repo_target_compatible_with: {type}`dict[str, list[str]]` mapping of repo names + to string labels that are added to the `target_compatible_with` for + the respective repo's toolchain. + repo_exec_compatible_with: {type}`dict[str, list[str]]` mapping of repo names + to string labels that are added to the `exec_compatible_with` for + the respective repo's toolchain. """ + i = 0 for i, repo in enumerate(version_aware_repo_names, start = i): - prefix = render.left_pad_zero(i, 4) + target_settings = ["@{}//:is_matching_python_version".format(repo)] + + if repo_target_settings.get(repo): + selects.config_setting_group( + name = "_{}_user_guard".format(repo), + match_all = repo_target_settings.get(repo, []) + target_settings, + ) + target_settings = ["_{}_user_guard".format(repo)] _internal_toolchain_suite( - prefix = prefix, + prefix = render.left_pad_zero(i, 4), runtime_repo_name = repo, - target_compatible_with = ["@{}//:os".format(repo)], - target_settings = ["@{}//:is_matching_python_version".format(repo)], + target_compatible_with = _get_local_toolchain_target_compatible_with( + repo, + repo_target_compatible_with, + ), + target_settings = target_settings, + exec_compatible_with = repo_exec_compatible_with.get(repo, []), ) # The version unaware entries must go last because they will match any Python # version. for i, repo in enumerate(version_unaware_repo_names, start = i + 1): - prefix = render.left_pad_zero(i, 4) _internal_toolchain_suite( - prefix = prefix, + prefix = render.left_pad_zero(i, 4) + "_default", runtime_repo_name = repo, - target_settings = [], - target_compatible_with = ["@{}//:os".format(repo)], + target_compatible_with = _get_local_toolchain_target_compatible_with( + repo, + repo_target_compatible_with, + ), + # We don't call _get_local_toolchain_target_settings because that + # will add the version matching condition by default. + target_settings = repo_target_settings.get(repo, []), + exec_compatible_with = repo_exec_compatible_with.get(repo, []), ) + +def _get_local_toolchain_target_compatible_with(repo, repo_target_compatible_with): + if repo in repo_target_compatible_with: + target_compatible_with = repo_target_compatible_with[repo] + if "HOST_CONSTRAINTS" in target_compatible_with: + target_compatible_with.remove("HOST_CONSTRAINTS") + target_compatible_with.extend(HOST_CONSTRAINTS) + else: + target_compatible_with = ["@{}//:os".format(repo)] + return target_compatible_with diff --git a/python/private/text_util.bzl b/python/private/text_util.bzl index a64b5d6243..28979d8981 100644 --- a/python/private/text_util.bzl +++ b/python/private/text_util.bzl @@ -108,6 +108,10 @@ def _render_list(items, *, hanging_indent = ""): def _render_str(value): return repr(value) +def _render_string_list_dict(value): + """Render an attr.string_list_dict value (`dict[str, list[str]`)""" + return _render_dict(value, value_repr = _render_list) + def _render_tuple(items, *, value_repr = repr): if not items: return "tuple()" @@ -166,4 +170,5 @@ render = struct( str = _render_str, toolchain_prefix = _toolchain_prefix, tuple = _render_tuple, + string_list_dict = _render_string_list_dict, ) diff --git a/tests/integration/local_toolchains/.bazelrc b/tests/integration/local_toolchains/.bazelrc index 39df41d9f4..aed08b0790 100644 --- a/tests/integration/local_toolchains/.bazelrc +++ b/tests/integration/local_toolchains/.bazelrc @@ -4,3 +4,5 @@ test --test_output=errors # Windows requires these for multi-python support: build --enable_runfiles common:bazel7.x --incompatible_python_disallow_native_rules +build --//:py=local +common --announce_rc diff --git a/tests/integration/local_toolchains/BUILD.bazel b/tests/integration/local_toolchains/BUILD.bazel index 02b126b0ea..6b731181a6 100644 --- a/tests/integration/local_toolchains/BUILD.bazel +++ b/tests/integration/local_toolchains/BUILD.bazel @@ -12,6 +12,7 @@ # See the License for the specific language governing permissions and # limitations under the License. +load("@bazel_skylib//rules:common_settings.bzl", "string_flag") load("@rules_python//python:py_test.bzl", "py_test") py_test( @@ -20,3 +21,17 @@ py_test( # Make this test better respect pyenv env_inherit = ["PYENV_VERSION"], ) + +config_setting( + name = "is_py_local", + flag_values = { + ":py": "local", + }, +) + +# Set `--//:py=local` to use the local toolchain +# (This is set in this example's .bazelrc) +string_flag( + name = "py", + build_setting_default = "", +) diff --git a/tests/integration/local_toolchains/MODULE.bazel b/tests/integration/local_toolchains/MODULE.bazel index 98f1ed9ac4..6c06909cd7 100644 --- a/tests/integration/local_toolchains/MODULE.bazel +++ b/tests/integration/local_toolchains/MODULE.bazel @@ -14,6 +14,9 @@ module(name = "module_under_test") bazel_dep(name = "rules_python", version = "0.0.0") +bazel_dep(name = "bazel_skylib", version = "1.7.1") +bazel_dep(name = "platforms", version = "0.0.11") + local_path_override( module_name = "rules_python", path = "../../..", @@ -32,6 +35,16 @@ local_runtime_repo( local_runtime_toolchains_repo( name = "local_toolchains", runtimes = ["local_python3"], + target_compatible_with = { + "local_python3": [ + "HOST_CONSTRAINTS", + ], + }, + target_settings = { + "local_python3": [ + "@//:is_py_local", + ], + }, ) python = use_extension("@rules_python//python/extensions:python.bzl", "python")