Fix comments and simplify a bit of code

CHANGELOG.md

@@ -31,6 +31,8 @@ This project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.htm
   It can be used to decode a `TraceState` from a `tracestate` header string value. (#1937)
 - The `Len` method is added to the `TraceState` type in the `go.opentelemetry.io/otel/trace` package.
   This method returns the number of list-members the `TraceState` holds. (#1937)
+- Changes `resource.NewWithAttributes` to require a schema URL. The old function is still available as `resource.NewSchemaless`. This is a breaking change. (#1938)
+- Several builtin resource detectors now correctly populate the schema URL. (#1938)
 
 ### Changed
 

sdk/resource/builtin.go

@@ -72,7 +72,8 @@ func (host) Detect(ctx context.Context) (*Resource, error) {
 }
 
 // StringDetector returns a Detector that will produce a *Resource
-// containing the string as a value corresponding to k.
+// containing the string as a value corresponding to k. The resulting Resource
+// will have the specified schemaURL.
 func StringDetector(schemaURL string, k attribute.Key, f func() (string, error)) Detector {
 	return stringDetector{schemaURL: schemaURL, K: k, F: f}
 }

sdk/resource/config.go

@@ -67,7 +67,7 @@ func WithBuiltinDetectors() Option {
 		fromEnv{})
 }
 
-// WithFromEnv adds attributes from environment variables to the  configured resource.
+// WithFromEnv adds attributes from environment variables to the configured resource.
 func WithFromEnv() Option {
 	return WithDetectors(fromEnv{})
 }
@@ -82,7 +82,7 @@ func WithTelemetrySDK() Option {
 	return WithDetectors(telemetrySDK{})
 }
 
-// WithSchemaURL sets the schema URL for the the configured resource.
+// WithSchemaURL sets the schema URL for the configured resource.
 func WithSchemaURL(schemaURL string) Option {
 	return schemaURLOption(schemaURL)
 }

sdk/resource/resource.go

@@ -59,14 +59,12 @@ func New(ctx context.Context, opts ...Option) (*Resource, error) {
 
 	resource, err := Detect(ctx, cfg.detectors...)
 
-	if resource != nil {
-		var err2 error
-		resource, err2 = Merge(resource, &Resource{schemaURL: cfg.schemaURL})
-		if err == nil {
-			err = err2
-		} else if err2 != nil {
-			err = fmt.Errorf("detecting resources: %s", []string{err.Error(), err2.Error()})
-		}
+	var err2 error
+	resource, err2 = Merge(resource, &Resource{schemaURL: cfg.schemaURL})
+	if err == nil {
+		err = err2
+	} else if err2 != nil {
+		err = fmt.Errorf("detecting resources: %s", []string{err.Error(), err2.Error()})
 	}
 
 	return resource, err

sdk/resource/resource_test.go

@@ -17,6 +17,7 @@ package resource_test
 import (
 	"context"
 	"encoding/json"
+	"errors"
 	"fmt"
 	"os"
 	"strings"
@@ -408,6 +409,7 @@ func TestNew(t *testing.T) {
 				resource.WithSchemaURL("https://opentelemetry.io/schemas/1.0.0"),
 			},
 			resourceValues: map[string]string{},
+			schemaURL:      "",
 			isErr:          true,
 		},
 		{
@@ -416,12 +418,12 @@ func TestNew(t *testing.T) {
 			options: []resource.Option{
 				resource.WithDetectors(
 					resource.StringDetector("https://opentelemetry.io/schemas/1.0.0", semconv.HostNameKey, os.Hostname),
-					resource.StringDetector("https://opentelemetry.io/schemas/1.1.0", semconv.HostNameKey, os.Hostname),
+					resource.StringDetector("https://opentelemetry.io/schemas/1.1.0", semconv.HostNameKey, func() (string, error) { return "", errors.New("fail") }),
 				),
 				resource.WithSchemaURL("https://opentelemetry.io/schemas/1.2.0"),
 			},
 			resourceValues: map[string]string{},
-			schemaURL:      "https://opentelemetry.io/schemas/1.2.0",
+			schemaURL:      "",
 			isErr:          true,
 		},
 	}