mdatagen: Add parent field to metadata.yaml file for subcomponents

This PR adds a `parent` field to the `metadata.yaml`. This is used in subcomponents, and the field contains the type of their parent component.

Issue: open-telemetry#23430

.chloggen/add-parent-field-metadata.yaml

@@ -0,0 +1,20 @@
+# Use this changelog template to create an entry for release notes.
+# If your change doesn't affect end users, such as a test fix or a tooling change,
+# you should instead start your pull request title with [chore] or use the "Skip Changelog" label.
+
+# One of 'breaking', 'deprecation', 'new_component', 'enhancement', 'bug_fix'
+change_type: enhancement
+
+# The name of the component, or a single word describing the area of concern, (e.g. filelogreceiver)
+component: mdatagen
+
+# A brief description of the change.  Surround your text with quotes ("") if it needs to start with a backtick (`).
+note: Adds a parent field to metadata.yaml for subcomponents.
+
+# Mandatory: One or more tracking issues related to the change. You can use the PR number here if no issue exists.
+issues: []
+
+# (Optional) One or more lines of additional information to render under the primary note.
+# These lines will be padded with 2 spaces and then inserted directly into the document.
+# Use pipe (|) for multiline entries.
+subtext:

cmd/mdatagen/loader.go

@@ -210,6 +210,8 @@ func (attr *attribute) Unmarshal(parser *confmap.Conf) error {
 type metadata struct {
 	// Type of the component.
 	Type string `mapstructure:"type"`
+	// Type of the parent component (applicable to subcomponents).
+	Parent string `mapstructure:"parent"`
 	// Status information for the component.
 	Status *Status `mapstructure:"status"`
 	// SemConvVersion is a version number of OpenTelemetry semantic conventions applied to the scraped metrics.

cmd/mdatagen/loader_test.go

@@ -158,6 +158,14 @@ func Test_loadMetadata(t *testing.T) {
 				ScopeName: "otelcol",
 			},
 		},
+		{
+			name: "testdata/parent.yaml",
+			want: metadata{
+				Type:      "subcomponent",
+				Parent:    "parentComponent",
+				ScopeName: "otelcol",
+			},
+		},
 		{
 			name:    "testdata/unknown_metric_attribute.yaml",
 			want:    metadata{},

cmd/mdatagen/metadata-schema.yaml

@@ -1,6 +1,9 @@
 # Required: The type of the component - Usually the name. The type and class combined uniquely identify the component (eg. receiver/otlp) or subcomponent (eg. receiver/hostmetricsreceiver/cpu)
 type:
 
+# Required for subcomponents: The type of the parent component.
+parent: string
+
 # Required for components (Optional for subcomponents): A high-level view of the development status and use of this component
 status:
   # Required: The class of the component (For example receiver)

cmd/mdatagen/templates/documentation.md.tmpl

@@ -38,6 +38,10 @@
 
 # {{ .Type }}
 
+{{- if .Parent }}
+**Parent Component:** {{ .Parent }}
+{{- end }}
+
 ## Default Metrics
 
 The following metrics are emitted by default. Each of them can be disabled by applying the following configuration:

cmd/mdatagen/testdata/parent.yaml

@@ -0,0 +1,3 @@
+type: subcomponent
+
+parent: parentComponent