[chore][cmd/mdatagen] Use metadata.yaml as a schema source for references (#15272)

<!--Ex. Fixing a bug - Describe the bug and how this fixes the issue.
Ex. Adding a feature - Explain what this achieves.-->
#### Description

Previously, the schemagen loader used `config.schema.yaml` as the
standalone file format for schema references. This PR changes the source
of truth for cross-component schema references to `metadata.yaml` — the
same file that already exists in every component directory.

Instead of parsing a bare ConfigMetadata JSON-schema object, the loader
now reads the config: section from a component's `metadata.yaml`,
matching the structure that mdatagen already generates for every
component. The generated output is likewise renamed to metadata.yaml
(placed under internal/metadata/) and wrapped with the standard
`metadata.yaml` envelope (type, status, config), so it is usable as a
reference target by other components in the same way.

<!-- Issue number if applicable -->
#### Link to tracking issue
Fixes #15259

<!--Describe what testing was performed and which tests were added.-->
#### Testing

Existing unit tests in `internal/schemagen` and `cmd/mdatagen/internal`
were updated to reflect the new file name and Metadata wrapper format.
The persistToFile test was strengthened to verify a full round-trip
through loadFromFile. All tests pass.

Author: jkoronaAtCisco

cmd/mdatagen/go.mod

@@ -8,7 +8,6 @@ require (
 	github.com/stretchr/testify v1.11.1
 	go.opentelemetry.io/collector/component v1.58.0
 	go.opentelemetry.io/collector/component/componenttest v0.152.0
-	go.opentelemetry.io/collector/config/confighttp v0.152.0
 	go.opentelemetry.io/collector/config/configoptional v1.58.0
 	go.opentelemetry.io/collector/confmap v1.58.0
 	go.opentelemetry.io/collector/confmap/provider/fileprovider v1.58.0
@@ -34,7 +33,6 @@ require (
 	go.opentelemetry.io/collector/receiver/receivertest v0.152.0
 	go.opentelemetry.io/collector/receiver/xreceiver v0.152.0
 	go.opentelemetry.io/collector/scraper v0.152.0
-	go.opentelemetry.io/collector/scraper/scraperhelper v0.152.0
 	go.opentelemetry.io/collector/scraper/scrapertest v0.152.0
 	go.opentelemetry.io/collector/scraper/xscraper v0.152.0
 	go.opentelemetry.io/collector/service/hostcapabilities v0.152.0
@@ -50,56 +48,34 @@ require (
 )
 
 require (
-	github.com/Microsoft/go-winio v0.6.2 // indirect
 	github.com/cespare/xxhash/v2 v2.3.0 // indirect
 	github.com/davecgh/go-spew v1.1.2-0.20180830191138-d8f796af33cc // indirect
-	github.com/felixge/httpsnoop v1.0.4 // indirect
-	github.com/foxboron/go-tpm-keyfiles v0.0.0-20251226215517-609e4778396f // indirect
-	github.com/fsnotify/fsnotify v1.10.1 // indirect
 	github.com/go-logr/logr v1.4.3 // indirect
 	github.com/go-logr/stdr v1.2.2 // indirect
 	github.com/go-viper/mapstructure/v2 v2.5.0 // indirect
 	github.com/gobwas/glob v0.2.3 // indirect
-	github.com/golang/snappy v1.0.0 // indirect
-	github.com/google/go-tpm v0.9.8 // indirect
 	github.com/google/uuid v1.6.0 // indirect
 	github.com/hashicorp/go-version v1.9.0 // indirect
 	github.com/inconshreveable/mousetrap v1.1.0 // indirect
 	github.com/json-iterator/go v1.1.12 // indirect
-	github.com/klauspost/compress v1.18.6 // indirect
 	github.com/knadh/koanf/maps v0.1.2 // indirect
 	github.com/knadh/koanf/providers/confmap v1.0.0 // indirect
 	github.com/knadh/koanf/v2 v2.3.4 // indirect
 	github.com/mitchellh/copystructure v1.2.0 // indirect
 	github.com/mitchellh/reflectwalk v1.0.2 // indirect
 	github.com/modern-go/concurrent v0.0.0-20180306012644-bacd9c7ef1dd // indirect
 	github.com/modern-go/reflect2 v1.0.3-0.20250322232337-35a7c28c31ee // indirect
-	github.com/pierrec/lz4/v4 v4.1.26 // indirect
 	github.com/pmezard/go-difflib v1.0.1-0.20181226105442-5d4384ee4fb2 // indirect
-	github.com/rs/cors v1.11.1 // indirect
 	github.com/spf13/pflag v1.0.10 // indirect
 	go.opentelemetry.io/auto/sdk v1.2.1 // indirect
-	go.opentelemetry.io/collector/client v1.58.0 // indirect
 	go.opentelemetry.io/collector/component/componentstatus v0.152.0 // indirect
-	go.opentelemetry.io/collector/config/configauth v1.58.0 // indirect
-	go.opentelemetry.io/collector/config/configcompression v1.58.0 // indirect
-	go.opentelemetry.io/collector/config/configmiddleware v1.58.0 // indirect
-	go.opentelemetry.io/collector/config/confignet v1.58.0 // indirect
-	go.opentelemetry.io/collector/config/configopaque v1.58.0 // indirect
-	go.opentelemetry.io/collector/config/configtls v1.58.0 // indirect
 	go.opentelemetry.io/collector/consumer/consumererror v0.152.0 // indirect
-	go.opentelemetry.io/collector/extension/extensionauth v1.58.0 // indirect
-	go.opentelemetry.io/collector/extension/extensionmiddleware v0.152.0 // indirect
 	go.opentelemetry.io/collector/internal/componentalias v0.152.0 // indirect
 	go.opentelemetry.io/collector/internal/fanoutconsumer v0.152.0 // indirect
 	go.opentelemetry.io/collector/pdata/testdata v0.152.0 // indirect
-	go.opentelemetry.io/collector/receiver/receiverhelper v0.152.0 // indirect
 	go.opentelemetry.io/collector/service v0.152.0 // indirect
-	go.opentelemetry.io/contrib/instrumentation/net/http/otelhttp v0.68.0 // indirect
 	go.opentelemetry.io/otel/sdk v1.43.0 // indirect
-	golang.org/x/crypto v0.51.0 // indirect
 	golang.org/x/mod v0.36.0 // indirect
-	golang.org/x/net v0.54.0 // indirect
 	golang.org/x/sync v0.20.0 // indirect
 	golang.org/x/sys v0.44.0 // indirect
 	golang.org/x/tools v0.45.0 // indirect
@@ -239,8 +215,4 @@ replace go.opentelemetry.io/collector/internal/componentalias => ../../internal/
 
 replace go.opentelemetry.io/collector/config/confignet => ../../config/confignet
 
-replace go.opentelemetry.io/collector/receiver/receiverhelper => ../../receiver/receiverhelper
-
-replace go.opentelemetry.io/collector/scraper/scraperhelper => ../../scraper/scraperhelper
-
 replace go.opentelemetry.io/collector/scraper/xscraper => ../../scraper/xscraper

cmd/mdatagen/go.sum

@@ -9,6 +9,7 @@ import (
 	"fmt"
 	"go/format"
 	"io/fs"
+	"maps"
 	"os"
 	"path/filepath"
 	"regexp"
@@ -194,7 +195,6 @@ func run(ymlPath string) error {
 		toGenerate[filepath.Join(tmplDir, "testdata", "config.yaml.tmpl")] = filepath.Join(testdataDir, "config.yaml")
 		toGenerate[filepath.Join(tmplDir, "config.go.tmpl")] = filepath.Join(codeDir, "generated_config.go")
 		toGenerate[filepath.Join(tmplDir, "config_test.go.tmpl")] = filepath.Join(codeDir, "generated_config_test.go")
-		toGenerate[filepath.Join(tmplDir, "config.schema.yaml.tmpl")] = filepath.Join(codeDir, "config.schema.yaml")
 	}
 
 	if len(md.ResourceAttributes) > 0 { // only generate resource files if resource attributes are configured
@@ -542,8 +542,42 @@ func validateYAMLKeyOrder(raw []byte) error {
 	return nil
 }
 
+func injectInternalMetadataDefs(md Metadata, mdDir string, src *cfggen.ConfigMetadata) error {
+	if len(md.Metrics) == 0 && len(md.Events) == 0 && len(md.ResourceAttributes) == 0 {
+		return nil
+	}
+	importRootPath, err := helpers.RootPackage(mdDir)
+	if err != nil {
+		return fmt.Errorf("unable to determine import root path: %w", err)
+	}
+	tmplFile := filepath.Join("templates", "config.schema.yaml.tmpl")
+	raw, err := executeTemplate(tmplFile, md, "metadata", importRootPath, getTemplateFuncMap(md, importRootPath))
+	if err != nil {
+		return fmt.Errorf("failed to render internal metadata defs: %w", err)
+	}
+	return mergeInternalMetadataDefs(raw, src)
+}
+
+func mergeInternalMetadataDefs(raw []byte, src *cfggen.ConfigMetadata) error {
+	var config cfggen.ConfigMetadata
+	if err := yaml.Unmarshal(raw, &config); err != nil {
+		return fmt.Errorf("failed to parse internal metadata defs: %w", err)
+	}
+	if len(config.Defs) == 0 {
+		return nil
+	}
+	if src.Defs == nil {
+		src.Defs = make(map[string]*cfggen.ConfigMetadata)
+	}
+	maps.Copy(src.Defs, config.Defs)
+	return nil
+}
+
 func generateConfigFiles(md Metadata, mdDir, _ string) error {
 	if md.Config != nil {
+		if err := injectInternalMetadataDefs(md, mdDir, md.Config); err != nil {
+			return err
+		}
 		resolver := cfggen.NewResolver(md.PackageName, md.Status.Class, md.Type, mdDir)
 		resolvedSchema, err := resolver.ResolveSchema(md.Config)
 		if err != nil {