Rename resource pkg label vars and methods (#1692)

* Rename resource pkg label vars and methods

The former `labels` package is now named `attributes` to conform with
the specification requirement. This removes the lingering `label` term
from the `resource` package.

Resolve https://github.com/open-telemetry/opentelemetry-go/issues/1691

* Update PR number in CHANGELOG

* Propagate rename to the prometheus exporter pkg

CHANGELOG.md

@@ -24,6 +24,7 @@ This project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.htm
 - Add `description` to SpanStatus only when `StatusCode` is set to error. (#1662)
 - `trace.SpanContext` is now immutable and has no exported fields. (#1573)
   - `trace.NewSpanContext()` can be used in conjunction with the `trace.SpanContextConfig` struct to initialize a new `SpanContext` where all values are known.
+- Renamed the `LabelSet` method of `"go.opentelemetry.io/otel/sdk/resource".Resource` to `Set`. (#1692)
 
 ### Removed
 

exporters/metric/prometheus/prometheus.go

@@ -349,7 +349,7 @@ func mergeLabels(record export.Record, keys, values *[]string) {
 
 	// Duplicate keys are resolved by taking the record label value over
 	// the resource value.
-	mi := attribute.NewMergeIterator(record.Labels(), record.Resource().LabelSet())
+	mi := attribute.NewMergeIterator(record.Labels(), record.Resource().Set())
 	for mi.Next() {
 		label := mi.Label()
 		if keys != nil {

sdk/resource/env.go

@@ -43,17 +43,17 @@ var _ Detector = FromEnv{}
 
 // Detect collects resources from environment
 func (FromEnv) Detect(context.Context) (*Resource, error) {
-	labels := strings.TrimSpace(os.Getenv(envVar))
+	attrs := strings.TrimSpace(os.Getenv(envVar))
 
-	if labels == "" {
+	if attrs == "" {
 		return Empty(), nil
 	}
-	return constructOTResources(labels)
+	return constructOTResources(attrs)
 }
 
 func constructOTResources(s string) (*Resource, error) {
 	pairs := strings.Split(s, ",")
-	labels := []attribute.KeyValue{}
+	attrs := []attribute.KeyValue{}
 	var invalid []string
 	for _, p := range pairs {
 		field := strings.SplitN(p, "=", 2)
@@ -62,11 +62,11 @@ func constructOTResources(s string) (*Resource, error) {
 			continue
 		}
 		k, v := strings.TrimSpace(field[0]), strings.TrimSpace(field[1])
-		labels = append(labels, attribute.String(k, v))
+		attrs = append(attrs, attribute.String(k, v))
 	}
 	var err error
 	if len(invalid) > 0 {
 		err = fmt.Errorf("%w: %v", errMissingValue, invalid)
 	}
-	return NewWithAttributes(labels...), err
+	return NewWithAttributes(attrs...), err
 }

sdk/resource/resource.go

@@ -29,7 +29,7 @@ import (
 // (`*resource.Resource`).  The `nil` value is equivalent to an empty
 // Resource.
 type Resource struct {
-	labels attribute.Set
+	attrs attribute.Set
 }
 
 var (
@@ -48,7 +48,7 @@ var (
 // value found for the key is preserved.
 func NewWithAttributes(kvs ...attribute.KeyValue) *Resource {
 	return &Resource{
-		labels: attribute.NewSet(kvs...),
+		attrs: attribute.NewSet(kvs...),
 	}
 }
 
@@ -61,7 +61,7 @@ func (r *Resource) String() string {
 	if r == nil {
 		return ""
 	}
-	return r.labels.Encoded(attribute.DefaultEncoder())
+	return r.attrs.Encoded(attribute.DefaultEncoder())
 }
 
 // Attributes returns a copy of attributes from the resource in a sorted order.
@@ -70,7 +70,7 @@ func (r *Resource) Attributes() []attribute.KeyValue {
 	if r == nil {
 		r = Empty()
 	}
-	return r.labels.ToSlice()
+	return r.attrs.ToSlice()
 }
 
 // Iter returns an interator of the Resource attributes.
@@ -79,7 +79,7 @@ func (r *Resource) Iter() attribute.Iterator {
 	if r == nil {
 		r = Empty()
 	}
-	return r.labels.Iter()
+	return r.attrs.Iter()
 }
 
 // Equal returns true when a Resource is equivalent to this Resource.
@@ -109,9 +109,9 @@ func Merge(a, b *Resource) *Resource {
 		return a
 	}
 
-	// Note: 'b' labels will overwrite 'a' with last-value-wins in attribute.Key()
+	// Note: 'b' attributes will overwrite 'a' with last-value-wins in attribute.Key()
 	// Meaning this is equivalent to: append(a.Attributes(), b.Attributes()...)
-	mi := attribute.NewMergeIterator(b.LabelSet(), a.LabelSet())
+	mi := attribute.NewMergeIterator(b.Set(), a.Set())
 	combine := make([]attribute.KeyValue, 0, a.Len()+b.Len())
 	for mi.Next() {
 		combine = append(combine, mi.Label())
@@ -135,24 +135,24 @@ func Default() *Resource {
 // between two resources.  This value is suitable for use as a key in
 // a map.
 func (r *Resource) Equivalent() attribute.Distinct {
-	return r.LabelSet().Equivalent()
+	return r.Set().Equivalent()
 }
 
-// LabelSet returns the equivalent *attribute.Set.
-func (r *Resource) LabelSet() *attribute.Set {
+// Set returns the equivalent *attribute.Set of this resources attributes.
+func (r *Resource) Set() *attribute.Set {
 	if r == nil {
 		r = Empty()
 	}
-	return &r.labels
+	return &r.attrs
 }
 
-// MarshalJSON encodes labels as a JSON list of { "Key": "...", "Value": ... }
-// pairs in order sorted by key.
+// MarshalJSON encodes the resource attributes as a JSON list of { "Key":
+// "...", "Value": ... } pairs in order sorted by key.
 func (r *Resource) MarshalJSON() ([]byte, error) {
 	if r == nil {
 		r = Empty()
 	}
-	return r.labels.MarshalJSON()
+	return r.attrs.MarshalJSON()
 }
 
 // Len returns the number of unique key-values in this Resource.
@@ -160,15 +160,13 @@ func (r *Resource) Len() int {
 	if r == nil {
 		return 0
 	}
-	return r.labels.Len()
+	return r.attrs.Len()
 }
 
-// Encoded returns an encoded representation of the resource by
-// applying a label encoder.  The result is cached by the underlying
-// label set.
+// Encoded returns an encoded representation of the resource.
 func (r *Resource) Encoded(enc attribute.Encoder) string {
 	if r == nil {
 		return ""
 	}
-	return r.labels.Encoded(enc)
+	return r.attrs.Encoded(enc)
 }

sdk/resource/resource_test.go

@@ -168,9 +168,9 @@ func TestMerge(t *testing.T) {
 func TestDefault(t *testing.T) {
 	res := resource.Default()
 	require.False(t, res.Equal(resource.Empty()))
-	require.True(t, res.LabelSet().HasValue(semconv.ServiceNameKey))
+	require.True(t, res.Set().HasValue(semconv.ServiceNameKey))
 
-	serviceName, _ := res.LabelSet().Value(semconv.ServiceNameKey)
+	serviceName, _ := res.Set().Value(semconv.ServiceNameKey)
 	require.True(t, strings.HasPrefix(serviceName.AsString(), "unknown_service:"))
 	require.Greaterf(t, len(serviceName.AsString()), len("unknown_service:"),
 		"default service.name should include executable name")