[DRAFT] [DO NOT MERGE] Entities support prototype

Makefile

@@ -168,7 +168,7 @@ ocb:
 # Definitions for ProtoBuf generation.
 
 # The source directory for OTLP ProtoBufs.
-OPENTELEMETRY_PROTO_SRC_DIR=pdata/internal/opentelemetry-proto
+OPENTELEMETRY_PROTO_SRC_DIR?=pdata/internal/opentelemetry-proto
 
 # The branch matching the current version of the proto to use
 OPENTELEMETRY_PROTO_VERSION=v1.4.0
@@ -200,7 +200,7 @@ genproto: genproto-cleanup
 	# Call a sub-make to ensure OPENTELEMETRY_PROTO_FILES is populated
 	$(MAKE) genproto_sub
 	$(MAKE) fmt
-	$(MAKE) genproto-cleanup
+	# $(MAKE) genproto-cleanup
 
 genproto_sub:
 	@echo Generating code for the following files:
@@ -234,8 +234,8 @@ genproto_sub:
 	cp -R $(PROTO_INTERMEDIATE_DIR)/$(PROTO_PACKAGE)/* $(PROTO_TARGET_GEN_DIR)/
 	rm -rf $(PROTO_INTERMEDIATE_DIR)/go.opentelemetry.io
 
-	@rm -rf $(OPENTELEMETRY_PROTO_SRC_DIR)/*
-	@rm -rf $(OPENTELEMETRY_PROTO_SRC_DIR)/.* > /dev/null 2>&1 || true
+	#@rm -rf $(OPENTELEMETRY_PROTO_SRC_DIR)/*
+	#@rm -rf $(OPENTELEMETRY_PROTO_SRC_DIR)/.* > /dev/null 2>&1 || true
 
 # Generate structs, functions and tests for pdata package. Must be used after any changes
 # to proto and after running `make genproto`

cmd/mdatagen/internal/metadata.go

@@ -29,6 +29,8 @@ type Metadata struct {
 	SemConvVersion string `mapstructure:"sem_conv_version"`
 	// ResourceAttributes that can be emitted by the component.
 	ResourceAttributes map[AttributeName]Attribute `mapstructure:"resource_attributes"`
+	// Entities associated with the emitted resource attributes.
+	Entities []Entity `mapstructure:"entities"`
 	// Attributes emitted by one or more metrics.
 	Attributes map[AttributeName]Attribute `mapstructure:"attributes"`
 	// Metrics that can be emitted by the component.
@@ -65,6 +67,9 @@ func (md *Metadata) Validate() error {
 	if err := md.validateMetrics(); err != nil {
 		errs = errors.Join(errs, err)
 	}
+	if err := md.validateEntities(); err != nil {
+		errs = errors.Join(errs, err)
+	}
 	return errs
 }
 
@@ -114,6 +119,18 @@ func (md *Metadata) validateMetrics() error {
 	return errs
 }
 
+func (md *Metadata) validateEntities() error {
+	var errs error
+	for _, entity := range md.Entities {
+		for _, attr := range append(entity.IDAttributes, entity.DescriptiveAttributes...) {
+			if _, ok := md.ResourceAttributes[attr]; !ok {
+				errs = errors.Join(errs, fmt.Errorf("undefined resource attribute: %v", attr))
+			}
+		}
+	}
+	return errs
+}
+
 func (md *Metadata) validateAttributes(usedAttrs map[AttributeName]bool) error {
 	var errs error
 	unusedAttrs := make([]AttributeName, 0, len(md.Attributes))
@@ -157,6 +174,15 @@ func validateMetrics(metrics map[MetricName]Metric, attributes map[AttributeName
 	return errs
 }
 
+type Entity struct {
+	// Type of the entity.
+	Type string `mapstructure:"type"`
+	// Identifying attributes of the entity.
+	IDAttributes []AttributeName `mapstructure:"id_attributes"`
+	// Descriptive attributes of the entity.
+	DescriptiveAttributes []AttributeName `mapstructure:"descriptive_attributes"`
+}
+
 type AttributeName string
 
 func (mn AttributeName) Render() (string, error) {

cmd/mdatagen/internal/status.go

@@ -109,6 +109,7 @@ func (ms StabilityMap) Validate() error {
 				c != "traces" &&
 				c != "logs" &&
 				c != "profiles" &&
+				c != "entities" &&
 				c != "traces_to_traces" &&
 				c != "traces_to_metrics" &&
 				c != "traces_to_logs" &&

cmd/mdatagen/internal/templates/resource.go.tmpl

@@ -46,6 +46,22 @@ func (rb *ResourceBuilder) Set{{ $name.Render }}(val {{ $attr.Type.Primitive }})
 // Emit returns the built resource and resets the internal builder state.
 func (rb *ResourceBuilder) Emit() pcommon.Resource {
 	r := rb.res
+	{{- range $entity := .Entities }}
+	{{- range $attr := .IDAttributes }}
+	_, found{{ $attr.Render }} := r.Attributes().Get("{{ $attr }}")
+	{{- end }}
+	if {{ range $i, $attr := .IDAttributes }}{{ if $i }}&& {{ end }}found{{ $attr.Render }} {{ else }}true {{ end }}{
+		ref := pcommon.NewResourceEntityRef()
+		ref.SetType("{{ $entity.Type }}")
+		ref.IdAttrKeys().Append({{ range $i, $attr := .IDAttributes }}{{ if $i }}, {{ end }}"{{ $attr }}"{{ end }})
+		{{- range $attr := .DescriptiveAttributes }}
+		if _, ok := r.Attributes().Get("{{ $attr }}"); ok {
+			ref.DescrAttrKeys().Append("{{ $attr }}")
+		}
+		{{- end }}
+		ref.CopyTo(r.Entities().AppendEmpty())
+	}
+	{{- end }}
 	rb.res = pcommon.NewResource()
 	return r
 }

cmd/mdatagen/metadata-schema.yaml

@@ -59,6 +59,13 @@ resource_attributes:
       # Should be used for deprecated optional resource_attributes that will be removed soon.
       if_configured:
 
+# Optional: list of entities associated with the produced resource.
+entities:
+  - type: string
+    # Array of attribute names that are used to identify the entity.
+    id_attributes: [string]
+    # Optional: array of attribute names that are used to describe the entity.
+    descriptive_attributes: [string]
 
 # Optional: map of attribute definitions with the key being the attribute name and value
 # being described below.