helm: add option to disable k8s manifest parsing for dependency infer…

…ence (#21282)

We have a lot of `helm_deployments`, so any `pants dependents` call is
super slow, because helm is trying to parse all the helm_deployments.
It's really sad, because we don't even use the docker image inference
and specify the dependencies manually!

So here I introduce a flag `--helm-infer-deployment-dependencies` which
can disable that costly parsing. The option controls whether Pants will
parse k8s manifests generated by helm to find dependencies on other
targets like docker images.

docs/notes/2.23.x.md

@@ -298,6 +298,8 @@ Fixed pulling `helm_artifact`s from OCI repositories.
 
 Improve warning on dependent images not being found. Pants can now validate that values passed into Helm charts that will be used for container images are valid `docker_image` targets or known 3rd-party images. See the [documentation in the helm-infer subsystem](https://www.pantsbuild.org/2.23/reference/subsystems/helm-infer).
 
+Added option `[helm-infer].deployment_dependencies` to disable costly parsing of k8s manifests.
+
 #### Shell
 
 Added `workspace_invalidation_sources` field to `adhoc_tool` and `shell_command` target types. This new field allows declaring that these targets depend on files without bringing those files into the execution sandbox, but that the target should still be re-executed if those files change. This is intended to work with the `workspace_environment` support where processes are executed in the workspace and not in a separate sandbox.

src/python/pants/backend/helm/dependency_inference/deployment.py

@@ -278,16 +278,32 @@ class InferHelmDeploymentDependenciesRequest(InferDependenciesRequest):
 @rule(desc="Find the dependencies needed by a Helm deployment")
 async def inject_deployment_dependencies(
     request: InferHelmDeploymentDependenciesRequest,
+    infer_subsystem: HelmInferSubsystem,
 ) -> InferredDependencies:
-    chart_address, explicitly_provided_deps, mapping = await MultiGet(
-        Get(Address, AddressInput, request.field_set.chart.to_address_input()),
-        Get(ExplicitlyProvidedDependencies, DependenciesRequest(request.field_set.dependencies)),
-        Get(
-            FirstPartyHelmDeploymentMapping,
-            FirstPartyHelmDeploymentMappingRequest(request.field_set),
-        ),
+    get_address = Get(Address, AddressInput, request.field_set.chart.to_address_input())
+    get_explicit_deps = Get(
+        ExplicitlyProvidedDependencies,
+        DependenciesRequest(request.field_set.dependencies),
     )
 
+    if infer_subsystem.deployment_dependencies:
+        chart_address, explicitly_provided_deps, mapping = await MultiGet(
+            get_address,
+            get_explicit_deps,
+            Get(
+                FirstPartyHelmDeploymentMapping,
+                FirstPartyHelmDeploymentMappingRequest(request.field_set),
+            ),
+        )
+    else:
+        (chart_address, explicitly_provided_deps), mapping = (
+            await MultiGet(get_address, get_explicit_deps),
+            FirstPartyHelmDeploymentMapping(
+                request.field_set.address,
+                FrozenYamlIndex.empty(),
+            ),
+        )
+
     dependencies: OrderedSet[Address] = OrderedSet()
     dependencies.add(chart_address)
 

src/python/pants/backend/helm/dependency_inference/subsystem.py

@@ -5,7 +5,7 @@
 from enum import Enum
 from functools import cached_property
 
-from pants.option.option_types import EnumOption, StrListOption
+from pants.option.option_types import BoolOption, EnumOption, StrListOption
 from pants.option.subsystem import Subsystem
 from pants.util.strutil import softwrap
 
@@ -73,6 +73,12 @@ class HelmInferSubsystem(Subsystem):
         ),
     )
 
+    deployment_dependencies = BoolOption(
+        default=True,
+        help="If true, parse k8s manifests generated by helm to find dependencies on other targets like docker images.",
+        advanced=True,
+    )
+
     @cached_property
     def external_base_images(self) -> set[str]:
         return set(self.external_docker_images)

src/python/pants/backend/helm/utils/yaml.py

@@ -159,7 +159,7 @@ def insert(
     def frozen(self) -> FrozenYamlIndex[T]:
         """Transforms this collection into a frozen (immutable) one."""
 
-        return FrozenYamlIndex(self)
+        return FrozenYamlIndex.create(self)
 
 
 @dataclass(frozen=True)
@@ -190,7 +190,8 @@ class FrozenYamlIndex(Generic[T]):
 
     _data: FrozenDict[PurePath, Collection[_YamlDocumentIndexNode[T]]]
 
-    def __init__(self, other: MutableYamlIndex[T]) -> None:
+    @classmethod
+    def create(cls, other: MutableYamlIndex[T]) -> FrozenYamlIndex[T]:
         data: dict[PurePath, Collection[_YamlDocumentIndexNode[T]]] = {}
         for file_path, doc_index in other._data.items():
             max_index = max(doc_index.keys())
@@ -202,7 +203,11 @@ def __init__(self, other: MutableYamlIndex[T]) -> None:
                 doc_list[idx] = _YamlDocumentIndexNode(paths=FrozenDict(item_map))
 
             data[file_path] = Collection(doc_list)
-        object.__setattr__(self, "_data", FrozenDict(data))
+        return FrozenYamlIndex(_data=FrozenDict(data))
+
+    @classmethod
+    def empty(cls: type[FrozenYamlIndex[T]]) -> FrozenYamlIndex[T]:
+        return FrozenYamlIndex[T](_data=FrozenDict())
 
     def transform_values(self, func: Callable[[T], Optional[R]]) -> FrozenYamlIndex[R]:
         """Transforms the values of the given indexed collection into those that are returned from