fix(tasks): locate v2 components by their def file's content, not just its name

comp/core/delegatedauth/def/delegatedauth.go was silently invisible to
components.lint-components because locate_component_def only recognized
'def/component.go' by exact filename. This meant its `// team: core-authn`
tag never made it into CODEOWNERS, and the component fell back to its
parent bundle's owner (agent-runtimes) instead.

locate_component_def now falls back to scanning 'def/' for a Go file
defining the Component interface, and check_component_contents_and_file_hiearchy
reports an explicit lint error when that file isn't named 'component.go',
so a misnamed def file is now caught instead of silently dropped.

Author: pgimalac

.github/CODEOWNERS

@@ -409,6 +409,7 @@
 /comp/core/configstream @DataDog/fleet-automation
 /comp/core/configstreamconsumer @DataDog/fleet-automation
 /comp/core/configsync @DataDog/fleet-automation
+/comp/core/delegatedauth @DataDog/core-authn
 /comp/core/diagnose @DataDog/fleet-remediation
 /comp/core/flare @DataDog/fleet-remediation
 /comp/core/gui @DataDog/fleet-remediation

comp/README.md

@@ -140,6 +140,12 @@ Package configstreamconsumer implements a component that consumes config streams
 
 Package configsync implements synchronizing the configuration using the core agent config API
 
+### [comp/core/delegatedauth](https://pkg.go.dev/github.com/DataDog/datadog-agent/comp/core/delegatedauth)
+
+*Datadog Team*: core-authn
+
+Package delegatedauth manages cloud-based delegated authentication for the agent.
+
 ### [comp/core/diagnose](https://pkg.go.dev/github.com/DataDog/datadog-agent/comp/core/diagnose)
 
 *Datadog Team*: fleet-remediation

comp/core/delegatedauth/def/BUILD.bazel

@@ -2,7 +2,7 @@ load("@rules_go//go:def.bzl", "go_library")
 
 go_library(
     name = "def",
-    srcs = ["delegatedauth.go"],
+    srcs = ["component.go"],
     importpath = "github.com/DataDog/datadog-agent/comp/core/delegatedauth/def",
     visibility = ["//visibility:public"],
     deps = [

…/core/delegatedauth/def/delegatedauth.go comp/core/delegatedauth/def/component.gocomp/core/delegatedauth/def/delegatedauth.go renamed to comp/core/delegatedauth/def/component.go comp/core/delegatedauth/def/delegatedauth.go renamed to comp/core/delegatedauth/def/component.go

@@ -169,6 +169,12 @@ def check_component_contents_and_file_hiearchy(comp):
     if comp.def_file == 'comp/api/api/def/component.go':
         return
 
+    # Definition file must be named 'component.go' for v2 components. This is found by content
+    # (its 'type Component' definition) rather than by name, so a wrongly-named file is reported
+    # here instead of silently failing to be recognized as the component's definition.
+    if comp.version == 2 and pathlib.Path(comp.def_file).name != 'component.go':
+        return f"** {comp.def_file} should be renamed to 'component.go'. See https://datadoghq.dev/datadog-agent/components/creating-components/"
+
     # Definition file `component.go` (v1) or `def/component.go` (v2) must use `package <compname>`
     pkgname = parse_package_name(comp.def_file)
     if pkgname != comp.name:
@@ -369,15 +375,40 @@ def get_components_and_bundles():
     return sorted(components, key=lambda c: c.path), sorted(sorted_bundles, key=lambda b: b.path)
 
 
+def find_component_def_file(def_dir):
+    """
+    Return the Go file in def_dir that defines the Component interface, if any.
+
+    Components are expected to name this file 'component.go' (checked separately in
+    check_component_contents_and_file_hiearchy), but we locate it here by content so that a
+    misnamed file still gets picked up as a component - and reported with an actionable error -
+    instead of silently vanishing from component/codeowners generation.
+    """
+    for entry in sorted(def_dir.iterdir()):
+        if not entry.is_file() or not entry.name.endswith('.go') or entry.name.endswith('_test.go'):
+            continue
+        content = read_file_content(entry).split('\n')
+        if any(line.startswith('type Component interface') or line.startswith('type Component = ') for line in content):
+            return entry
+
+    return None
+
+
 def locate_component_def(dir):
     """
     Locate the component, if this directory contains a component
     """
     component_name = dir.name.replace('-', '').lower()
 
-    # v2 component: this folder is a component root if it contains 'def/component.go'
+    # v2 component: this folder is a component root if it contains 'def/component.go', or, failing
+    # that, another Go file in 'def' that defines the Component interface (see find_component_def_file)
     def_file = dir / 'def/component.go'
-    if def_file.is_file():
+    if not def_file.is_file():
+        def_subdir = dir / 'def'
+        if def_subdir.is_dir():
+            def_file = find_component_def_file(def_subdir)
+
+    if def_file is not None and def_file.is_file():
         # comp/api/api/def/component.go is a special case, it's not a component using version 2
         # PLEASE DO NOT ADD MORE EXCEPTIONS
         if to_posix_path(def_file) == "comp/api/api/def/component.go":

tasks/components.py

@@ -61,6 +61,18 @@ def test_locate_root(self):
         root = components.locate_component_def(Path('comp/newstyle'))
         self.assertEqual(2, root.version)
 
+    def test_locate_root_misnamed_def_file(self):
+        # A def/component.go file that isn't named 'component.go' should still be located as the
+        # component's definition file (by its 'type Component' definition), rather than silently
+        # not being recognized as a component at all.
+        oldfilename = os.path.join('comp/newstyle', 'def/component.go')
+        newfilename = os.path.join('comp/newstyle', 'def/newstyle.go')
+        shutil.move(oldfilename, newfilename)
+
+        root = components.locate_component_def(Path('comp/newstyle'))
+        self.assertEqual(2, root.version)
+        self.assertEqual(components.to_posix_path(newfilename), root.def_file)
+
     def test_validate_bundles(self):
         _, bundles = components.get_components_and_bundles()
         errs = components.validate_bundles(bundles)
@@ -137,6 +149,18 @@ def test_validate_component_definition(self):
         self.assertEqual(1, len(errs))
         self.assertIn('separate implementation', errs[0])
 
+        # Lint error because def/component.go should be named 'component.go'
+        self.reset_component_src_in_tmpdir()
+
+        oldfilename = os.path.join(comps[3].path, 'def/component.go')
+        newfilename = os.path.join(comps[3].path, 'def/newstyle.go')
+        shutil.move(oldfilename, newfilename)
+
+        comps, _ = components.get_components_and_bundles()
+        errs = components.validate_components(comps)
+        self.assertEqual(1, len(errs))
+        self.assertIn("should be renamed to 'component.go'", errs[0])
+
     def test_validate_component_fx(self):
         comps, _ = components.get_components_and_bundles()
         errs = components.validate_components(comps)