Support multiple entity refs in the Resource

attribute/set.go

@@ -307,6 +307,15 @@ func filteredToFront(slice []KeyValue, keep Filter) int {
 	return j
 }
 
+func (l *Set) Clone() Set {
+	s, _ := l.Filter(
+		func(KeyValue) bool {
+			return true
+		},
+	)
+	return s
+}
+
 // Filter returns a filtered copy of this Set. See the documentation for
 // NewSetWithSortableFiltered for more details.
 func (l *Set) Filter(re Filter) (Set, []KeyValue) {

example/dice/otel.go

@@ -86,14 +86,24 @@ func setupOTelSDK(ctx context.Context, serviceName, serviceVersion string) (
 }
 
 func newResource(serviceName, serviceVersion string) (*resource.Resource, error) {
-	return resource.Merge(
-		resource.Default(),
-		resource.NewWithAttributes(
+	res, err := resource.New(
+		context.Background(),
+		resource.WithHost(),
+		resource.WithHostID(),
+		resource.WithEntity(
 			semconv.SchemaURL,
+			"service",
 			semconv.ServiceName(serviceName),
 			semconv.ServiceVersion(serviceVersion),
 		),
 	)
+	if err != nil {
+		return nil, err
+	}
+	return resource.Merge(
+		resource.Default(),
+		res,
+	)
 }
 
 func newPropagator() propagation.TextMapPropagator {

exporters/otlp/otlptrace/internal/tracetransform/resource.go

@@ -27,11 +27,21 @@ func Resource(r *resource.Resource) *resourcepb.Resource {
 	}
 
 	attrs := Iterator(r.Iter())
-	entityId := Iterator(r.EntityId().Iter())
 
-	return &resourcepb.Resource{
+	out := &resourcepb.Resource{
 		Attributes: attrs,
-		EntityType: r.EntityType(),
-		EntityId:   entityId,
 	}
+
+	for _, entity := range r.EntityRefs() {
+		out.Entities = append(
+			out.Entities, &resourcepb.ResourceEntityRef{
+				SchemaUrl:     entity.SchemaUrl,
+				Type:          entity.Type,
+				IdAttrKeys:    entity.IdKeys,
+				DescrAttrKeys: entity.AttrsKeys,
+			},
+		)
+	}
+
+	return out
 }

go.sum

@@ -9,6 +9,7 @@ github.com/google/go-cmp v0.6.0 h1:ofyhxvXcZhMsU5ulbFiLKl/XBFqE1GSq7atu8tAmTRI=
 github.com/google/go-cmp v0.6.0/go.mod h1:17dUlkBOakJ0+DkrSSNjCkIjxS6bF9zb3elmeNGIjoY=
 github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
 github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
+github.com/stretchr/objx v0.5.0/go.mod h1:Yh+to48EsGEfYuaHDzXPcE3xhTkx73EhmCGUpEOglKo=
 github.com/stretchr/testify v1.8.4 h1:CcVxjf3Q8PM0mHUKJCdn+eZZtm5yQwehR5yeSVQQcUk=
 github.com/stretchr/testify v1.8.4/go.mod h1:sz/lmYIOXD/1dqDmKjjqLyZ2RngseejIcXlSw2iwfAo=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405 h1:yhCVgyC4o1eVCa2tZl7eS0r+SDo693bJlVdllGtEeKM=

sdk/resource/builtin.go

@@ -22,7 +22,6 @@ import (
 
 	"go.opentelemetry.io/otel/attribute"
 	"go.opentelemetry.io/otel/sdk"
-	"go.opentelemetry.io/otel/sdk/resource/internal"
 	semconv "go.opentelemetry.io/otel/semconv/v1.24.0"
 )
 
@@ -70,7 +69,12 @@ func (telemetrySDK) Detect(context.Context) (*Resource, error) {
 
 // Detect returns a *Resource that describes the host being run on.
 func (host) Detect(ctx context.Context) (*Resource, error) {
-	return StringDetector(semconv.SchemaURL, semconv.HostNameKey, os.Hostname).Detect(ctx)
+	return StringDetectorWithEntity(
+		semconv.SchemaURL,
+		"host",
+		semconv.HostNameKey,
+		os.Hostname,
+	).Detect(ctx)
 }
 
 // StringDetector returns a Detector that will produce a *Resource
@@ -100,12 +104,12 @@ func (sd stringDetector) Detect(ctx context.Context) (*Resource, error) {
 		return nil, fmt.Errorf("invalid attribute: %q -> %q", a.Key, a.Value.Emit())
 	}
 	id := attribute.NewSet(sd.K.String(value))
-	entity := internal.EntityData{
-		Type:  sd.entityType,
-		Id:    id,
-		Attrs: id,
+	entity := Entity{
+		Type:      sd.entityType,
+		Id:        id,
+		SchemaURL: sd.schemaURL,
 	}
-	return NewWithEntity(sd.schemaURL, &entity), nil
+	return NewWithEntities([]Entity{entity})
 }
 
 // Detect implements Detector.

sdk/resource/config.go

@@ -27,8 +27,8 @@ type config struct {
 	// SchemaURL to associate with the Resource.
 	schemaURL string
 
-	entityType string
-	entityId   []attribute.KeyValue
+	//entityType string
+	//entityId   []attribute.KeyValue
 }
 
 // Option is the interface that applies a configuration option.
@@ -96,22 +96,48 @@ func (o schemaURLOption) apply(cfg config) config {
 	return cfg
 }
 
-// WithEntity sets the schema URL for the configured resource.
-func WithEntity(entityType string, entityId ...attribute.KeyValue) Option {
-	return entityOption{entityType, entityId}
+type entityDetector struct {
+	SchemaURL string
+	Type      string
+	Id        []attribute.KeyValue
+	Attrs     []attribute.KeyValue
 }
 
-type entityOption struct {
-	entityType string
-	entityId   []attribute.KeyValue
+func (e entityDetector) Detect(ctx context.Context) (*Resource, error) {
+	return NewWithEntities(
+		[]Entity{
+			{
+				Type:      e.Type,
+				Id:        attribute.NewSet(e.Id...),
+				Attrs:     attribute.NewSet(e.Attrs...),
+				SchemaURL: e.SchemaURL,
+			},
+		},
+	)
 }
 
-func (o entityOption) apply(cfg config) config {
-	cfg.entityType = o.entityType
-	cfg.entityId = o.entityId
-	return cfg
+// WithEntity sets the schema URL for the configured resource.
+func WithEntity(schemaURL string, entityType string, Id ...attribute.KeyValue) Option {
+	return WithDetectors(
+		entityDetector{
+			SchemaURL: schemaURL,
+			Type:      entityType,
+			Id:        Id,
+		},
+	)
 }
 
+//type entityOption struct {
+//	entityType string
+//	entityId   []attribute.KeyValue
+//}
+//
+//func (o entityOption) apply(cfg config) config {
+//	cfg.entityType = o.entityType
+//	cfg.entityId = o.entityId
+//	return cfg
+//}
+
 // WithOS adds all the OS attributes to the configured Resource.
 // See individual WithOS* functions to configure specific attributes.
 func WithOS() Option {

sdk/resource/entity.go

@@ -0,0 +1,10 @@
+package resource
+
+import "go.opentelemetry.io/otel/attribute"
+
+type Entity struct {
+	Type      string
+	Id        attribute.Set
+	Attrs     attribute.Set
+	SchemaURL string
+}

sdk/resource/entityref.go

@@ -0,0 +1,29 @@
+package resource
+
+import "go.opentelemetry.io/otel/attribute"
+
+type resourceEntityRef struct {
+	SchemaUrl string
+
+	// Defines the entity type, e.g "service", "k8s.pod", etc.
+	Type string
+
+	// Set of Resource attribute keys that identify the entity.
+	Id map[attribute.Key]bool
+
+	// Set of Resource attribute keys that describe the entity.
+	Attrs map[attribute.Key]bool
+
+	// Id and Attrs materialized as slices for faster exporting.
+	IdKeys    []string
+	AttrsKeys []string
+}
+
+func (r *resourceEntityRef) materialize() {
+	for k := range r.Id {
+		r.IdKeys = append(r.IdKeys, string(k))
+	}
+	for k := range r.Attrs {
+		r.AttrsKeys = append(r.AttrsKeys, string(k))
+	}
+}

sdk/resource/host_id.go

@@ -113,8 +113,12 @@ func (hostIDDetector) Detect(ctx context.Context) (*Resource, error) {
 		return nil, err
 	}
 
-	return NewWithAttributes(
+	return StringDetectorWithEntity(
 		semconv.SchemaURL,
-		semconv.HostID(hostID),
-	), nil
+		"host",
+		semconv.HostIDKey,
+		func() (string, error) {
+			return hostID, nil
+		},
+	).Detect(ctx)
 }