Remove [python-protobuf].runtime_dependencies in favor of Pants dis…

…covering the dependency (pantsbuild#14691)

@tdyas had the idea that rather than you having to tell Pants where to load `protobuf`, `grpcio`, and `thrift`, we can simply discover it! We do this for Scala already and it works well.

There's minimal performance hit because we already will have created a third-party module mapping.

Two motivations:

1. Ergonomics.
2. Unblock codegen supporting multiple resolves: pantsbuild#14484. Otherwise we would need to add `[python-protobuf].runtime_dependencies_per_resolve`, which violates our goal for resolves to not make things more complex for the average user who only wants one resolve.

Note that this was already deprecated in 2.10, so we can outright remove here.

[ci skip-rust]

# Building wheels and fs_util will be skipped. Delete if not intended.
[ci skip-build-wheels]

src/python/pants/backend/codegen/protobuf/java/rules_integration_test.py

@@ -9,9 +9,6 @@
 
 from pants.backend.codegen.protobuf.java.rules import GenerateJavaFromProtobufRequest
 from pants.backend.codegen.protobuf.java.rules import rules as protobuf_rules
-from pants.backend.codegen.protobuf.python.python_protobuf_subsystem import (
-    rules as protobuf_subsystem_rules,
-)
 from pants.backend.codegen.protobuf.target_types import (
     ProtobufSourceField,
     ProtobufSourcesGeneratorTarget,
@@ -50,7 +47,6 @@ def rule_runner() -> RuleRunner:
     return RuleRunner(
         rules=[
             *protobuf_rules(),
-            *protobuf_subsystem_rules(),
             *stripped_source_files.rules(),
             *target_types_rules(),
             QueryRule(HydratedSources, [HydrateSourcesRequest]),

src/python/pants/backend/codegen/protobuf/python/python_protobuf_subsystem.py

@@ -2,16 +2,21 @@
 # Licensed under the Apache License, Version 2.0 (see LICENSE).
 
 
-from pants.backend.codegen.protobuf.target_types import ProtobufDependenciesField
+from pants.backend.codegen.protobuf.target_types import (
+    ProtobufDependenciesField,
+    ProtobufGrpcToggleField,
+)
+from pants.backend.codegen.utils import find_python_runtime_library_or_raise_error
+from pants.backend.python.dependency_inference.module_mapper import ThirdPartyPythonModuleMapping
 from pants.backend.python.goals import lockfile
 from pants.backend.python.goals.lockfile import GeneratePythonLockfile
 from pants.backend.python.subsystems.python_tool_base import PythonToolRequirementsBase
 from pants.core.goals.generate_lockfiles import GenerateToolLockfileSentinel
-from pants.engine.addresses import Addresses, UnparsedAddressInputs
+from pants.engine.addresses import Address
 from pants.engine.rules import Get, collect_rules, rule
-from pants.engine.target import InjectDependenciesRequest, InjectedDependencies
+from pants.engine.target import InjectDependenciesRequest, InjectedDependencies, WrappedTarget
 from pants.engine.unions import UnionRule
-from pants.option.option_types import BoolOption, TargetListOption
+from pants.option.option_types import BoolOption
 from pants.option.subsystem import Subsystem
 from pants.util.docutil import doc_url, git_url
 
@@ -20,16 +25,6 @@ class PythonProtobufSubsystem(Subsystem):
     options_scope = "python-protobuf"
     help = f"Options related to the Protobuf Python backend.\n\nSee {doc_url('protobuf')}."
 
-    _runtime_dependencies = TargetListOption(
-        "--runtime-dependencies",
-        help=(
-            "A list of addresses to `python_requirement` targets for the runtime "
-            "dependencies needed for generated Python code to work. For example, "
-            "`['3rdparty/python:protobuf', '3rdparty/python:grpcio']`. These dependencies will "
-            "be automatically added to every `protobuf_sources` target"
-        ),
-    )
-
     mypy_plugin = BoolOption(
         "--mypy-plugin",
         default=False,
@@ -39,9 +34,19 @@ class PythonProtobufSubsystem(Subsystem):
         ),
     )
 
-    @property
-    def runtime_dependencies(self) -> UnparsedAddressInputs:
-        return UnparsedAddressInputs(self._runtime_dependencies, owning_address=None)
+    infer_runtime_dependency = BoolOption(
+        "--infer-runtime-dependency",
+        default=True,
+        help=(
+            "If True, will add a dependency on a `python_requirement` target exposing the "
+            "`protobuf` module (usually from the `protobuf` requirement). If the `protobuf_source` "
+            "target sets `grpc=True`, will also add a dependency on the `python_requirement` "
+            "target exposing the `grpcio` module.\n\n"
+            "Unless this option is disabled, Pants will error if no relevant target is found or "
+            "if more than one is found which causes ambiguity."
+        ),
+        advanced=True,
+    )
 
 
 class PythonProtobufMypyPlugin(PythonToolRequirementsBase):
@@ -81,10 +86,40 @@ class InjectPythonProtobufDependencies(InjectDependenciesRequest):
 
 @rule
 async def inject_dependencies(
-    _: InjectPythonProtobufDependencies, python_protobuf: PythonProtobufSubsystem
+    request: InjectPythonProtobufDependencies,
+    python_protobuf: PythonProtobufSubsystem,
+    # TODO(#12946): Make this a lazy Get once possible.
+    module_mapping: ThirdPartyPythonModuleMapping,
 ) -> InjectedDependencies:
-    addresses = await Get(Addresses, UnparsedAddressInputs, python_protobuf.runtime_dependencies)
-    return InjectedDependencies(addresses)
+    if not python_protobuf.infer_runtime_dependency:
+        return InjectedDependencies()
+
+    result = [
+        find_python_runtime_library_or_raise_error(
+            module_mapping,
+            request.dependencies_field.address,
+            "google.protobuf",
+            recommended_requirement_name="protobuf",
+            recommended_requirement_url="https://pypi.org/project/protobuf/",
+            disable_inference_option=f"[{python_protobuf.options_scope}].infer_runtime_dependency",
+        )
+    ]
+
+    wrapped_tgt = await Get(WrappedTarget, Address, request.dependencies_field.address)
+    if wrapped_tgt.target.get(ProtobufGrpcToggleField).value:
+        result.append(
+            find_python_runtime_library_or_raise_error(
+                module_mapping,
+                request.dependencies_field.address,
+                # Note that the library is called `grpcio`, but the module is `grpc`.
+                "grpc",
+                recommended_requirement_name="grpcio",
+                recommended_requirement_url="https://pypi.org/project/grpcio/",
+                disable_inference_option=f"[{python_protobuf.options_scope}].infer_runtime_dependency",
+            )
+        )
+
+    return InjectedDependencies(result)
 
 
 def rules():

src/python/pants/backend/codegen/protobuf/python/python_protobuf_subsystem_test.py

@@ -1,45 +1,62 @@
 # Copyright 2020 Pants project contributors (see CONTRIBUTORS.md).
 # Licensed under the Apache License, Version 2.0 (see LICENSE).
-
 from pants.backend.codegen.protobuf import target_types
 from pants.backend.codegen.protobuf.python import python_protobuf_subsystem
 from pants.backend.codegen.protobuf.python.python_protobuf_subsystem import (
     InjectPythonProtobufDependencies,
 )
-from pants.backend.codegen.protobuf.target_types import (
-    ProtobufDependenciesField,
-    ProtobufSourcesGeneratorTarget,
+from pants.backend.codegen.protobuf.target_types import ProtobufSourcesGeneratorTarget
+from pants.backend.codegen.utils import (
+    AmbiguousPythonCodegenRuntimeLibrary,
+    MissingPythonCodegenRuntimeLibrary,
 )
-from pants.core.target_types import GenericTarget
+from pants.backend.python.dependency_inference import module_mapper
+from pants.backend.python.target_types import PythonRequirementTarget
+from pants.core.util_rules import stripped_source_files
 from pants.engine.addresses import Address
-from pants.engine.target import InjectedDependencies
-from pants.testutil.rule_runner import QueryRule, RuleRunner
+from pants.engine.target import Dependencies, InjectedDependencies
+from pants.testutil.rule_runner import QueryRule, RuleRunner, engine_error
 
 
-def test_inject_dependencies() -> None:
+def test_find_protobuf_python_requirement() -> None:
     rule_runner = RuleRunner(
         rules=[
             *python_protobuf_subsystem.rules(),
             *target_types.rules(),
+            *module_mapper.rules(),
+            *stripped_source_files.rules(),
             QueryRule(InjectedDependencies, (InjectPythonProtobufDependencies,)),
         ],
-        target_types=[ProtobufSourcesGeneratorTarget, GenericTarget],
+        target_types=[ProtobufSourcesGeneratorTarget, PythonRequirementTarget],
     )
-    rule_runner.set_options(["--python-protobuf-runtime-dependencies=protos:injected_dep"])
-    # Note that injected deps can be any target type for `--python-protobuf-runtime-dependencies`.
+
     rule_runner.write_files(
-        {
-            "protos/BUILD": "protobuf_sources()\ntarget(name='injected_dep')",
-            "protos/f.proto": "",
-        }
+        {"codegen/dir/f.proto": "", "codegen/dir/BUILD": "protobuf_sources(grpc=True)"}
     )
+    proto_tgt = rule_runner.get_target(Address("codegen/dir", relative_file_path="f.proto"))
+    request = InjectPythonProtobufDependencies(proto_tgt[Dependencies])
 
-    def assert_injected(addr: Address) -> None:
-        tgt = rule_runner.get_target(addr)
-        injected = rule_runner.request(
-            InjectedDependencies, [InjectPythonProtobufDependencies(tgt[ProtobufDependenciesField])]
-        )
-        assert injected == InjectedDependencies([Address("protos", target_name="injected_dep")])
+    # Start with no relevant requirements.
+    with engine_error(MissingPythonCodegenRuntimeLibrary, contains="protobuf"):
+        rule_runner.request(InjectedDependencies, [request])
+    rule_runner.write_files({"proto1/BUILD": "python_requirement(requirements=['protobuf'])"})
+    with engine_error(MissingPythonCodegenRuntimeLibrary, contains="grpcio"):
+        rule_runner.request(InjectedDependencies, [request])
+
+    # If exactly one, match it.
+    rule_runner.write_files({"grpc1/BUILD": "python_requirement(requirements=['grpc'])"})
+    assert rule_runner.request(InjectedDependencies, [request]) == InjectedDependencies(
+        [Address("proto1"), Address("grpc1")]
+    )
 
-    assert_injected(Address("protos"))
-    assert_injected(Address("protos", relative_file_path="f.proto"))
+    # If multiple, error.
+    rule_runner.write_files({"grpc2/BUILD": "python_requirement(requirements=['grpc'])"})
+    with engine_error(
+        AmbiguousPythonCodegenRuntimeLibrary, contains="['grpc1:grpc1', 'grpc2:grpc2']"
+    ):
+        rule_runner.request(InjectedDependencies, [request])
+    rule_runner.write_files({"proto2/BUILD": "python_requirement(requirements=['protobuf'])"})
+    with engine_error(
+        AmbiguousPythonCodegenRuntimeLibrary, contains="['proto1:proto1', 'proto2:proto2']"
+    ):
+        rule_runner.request(InjectedDependencies, [request])

src/python/pants/backend/codegen/protobuf/python/register.py

@@ -20,6 +20,8 @@
     ProtobufSourceTarget,
 )
 from pants.backend.codegen.protobuf.target_types import rules as protobuf_target_rules
+from pants.backend.python.dependency_inference import module_mapper
+from pants.core.util_rules import stripped_source_files
 
 
 def rules():
@@ -32,6 +34,8 @@ def rules():
         *protobuf_tailor.rules(),
         *export_codegen_goal.rules(),
         *protobuf_target_rules(),
+        *module_mapper.rules(),
+        *stripped_source_files.rules(),
     ]
 
 

src/python/pants/backend/codegen/protobuf/python/rules_integration_test.py

@@ -19,6 +19,7 @@
     ProtobufSourcesGeneratorTarget,
 )
 from pants.backend.codegen.protobuf.target_types import rules as target_types_rules
+from pants.backend.python.dependency_inference import module_mapper
 from pants.core.util_rules import stripped_source_files
 from pants.engine.addresses import Address
 from pants.engine.target import GeneratedSources, HydratedSources, HydrateSourcesRequest
@@ -58,6 +59,7 @@ def rule_runner() -> RuleRunner:
             *additional_fields.rules(),
             *stripped_source_files.rules(),
             *target_types_rules(),
+            *module_mapper.rules(),
             QueryRule(HydratedSources, [HydrateSourcesRequest]),
             QueryRule(GeneratedSources, [GeneratePythonFromProtobufRequest]),
         ],
@@ -74,7 +76,11 @@ def assert_files_generated(
     mypy: bool = False,
     extra_args: list[str] | None = None,
 ) -> None:
-    args = [f"--source-root-patterns={repr(source_roots)}", *(extra_args or ())]
+    args = [
+        f"--source-root-patterns={repr(source_roots)}",
+        "--no-python-protobuf-infer-runtime-dependency",
+        *(extra_args or ()),
+    ]
     if mypy:
         args.append("--python-protobuf-mypy-plugin")
     rule_runner.set_options(args, env_inherit={"PATH", "PYENV_ROOT", "HOME"})

src/python/pants/backend/codegen/thrift/apache/python/register.py

@@ -9,6 +9,8 @@
     ThriftSourcesGeneratorTarget,
     ThriftSourceTarget,
 )
+from pants.backend.python.dependency_inference import module_mapper
+from pants.core.util_rules import stripped_source_files
 
 
 def target_types():
@@ -21,4 +23,6 @@ def rules():
         *apache_thrift_rules(),
         *apache_thrift_python_rules(),
         *python_thrift_module_mapper.rules(),
+        *module_mapper.rules(),
+        *stripped_source_files.rules(),
     ]

src/python/pants/backend/codegen/thrift/apache/python/rules.py

@@ -1,15 +1,18 @@
 # Copyright 2021 Pants project contributors (see CONTRIBUTORS.md).
 # Licensed under the Apache License, Version 2.0 (see LICENSE).
 
+from __future__ import annotations
+
 from pants.backend.codegen.thrift.apache.python import subsystem
 from pants.backend.codegen.thrift.apache.python.subsystem import ThriftPythonSubsystem
 from pants.backend.codegen.thrift.apache.rules import (
     GeneratedThriftSources,
     GenerateThriftSourcesRequest,
 )
 from pants.backend.codegen.thrift.target_types import ThriftDependenciesField, ThriftSourceField
+from pants.backend.codegen.utils import find_python_runtime_library_or_raise_error
+from pants.backend.python.dependency_inference.module_mapper import ThirdPartyPythonModuleMapping
 from pants.backend.python.target_types import PythonSourceField
-from pants.engine.addresses import Addresses, UnparsedAddressInputs
 from pants.engine.fs import AddPrefix, Digest, Snapshot
 from pants.engine.internals.selectors import Get
 from pants.engine.rules import collect_rules, rule
@@ -63,11 +66,24 @@ class InjectApacheThriftPythonDependencies(InjectDependenciesRequest):
 
 
 @rule
-async def inject_apache_thrift_java_dependencies(
-    _: InjectApacheThriftPythonDependencies, thrift_python: ThriftPythonSubsystem
+async def find_apache_thrift_python_requirement(
+    request: InjectApacheThriftPythonDependencies,
+    thrift_python: ThriftPythonSubsystem,
+    # TODO(#12946): Make this a lazy Get once possible.
+    module_mapping: ThirdPartyPythonModuleMapping,
 ) -> InjectedDependencies:
-    addresses = await Get(Addresses, UnparsedAddressInputs, thrift_python.runtime_dependencies)
-    return InjectedDependencies(addresses)
+    if not thrift_python.infer_runtime_dependency:
+        return InjectedDependencies()
+
+    addr = find_python_runtime_library_or_raise_error(
+        module_mapping,
+        request.dependencies_field.address,
+        "thrift",
+        recommended_requirement_name="thrift",
+        recommended_requirement_url="https://pypi.org/project/thrift/",
+        disable_inference_option=f"[{thrift_python.options_scope}].infer_runtime_dependency",
+    )
+    return InjectedDependencies([addr])
 
 
 def rules():