PIP-1618: Simplify OTel resource configuration. (#114)

tracing/README.md

@@ -147,14 +147,7 @@ import (
 	semconv "go.opentelemetry.io/otel/semconv/v1.10.0"
 )
 
-res, err := resource.Merge(
-	resource.Default(),
-	resource.NewWithAttributes(
-		semconv.SchemaURL,
-		semconv.ServiceNameKey.String("My service"),
-		semconv.ServiceVersionKey.String("v1.0.0"),
-	),
-)
+res, err := tracing.NewResource("My service", "v1.0.0")
 ctx, tracer, err := tracing.InitTracing(ctx, "github.com/myrepo/myservice", sdktrace.WithResource(res))
 ```
 

tracing/tracing.go

@@ -12,7 +12,9 @@ import (
 	"go.opentelemetry.io/otel"
 	"go.opentelemetry.io/otel/exporters/jaeger"
 	"go.opentelemetry.io/otel/propagation"
+	"go.opentelemetry.io/otel/sdk/resource"
 	sdktrace "go.opentelemetry.io/otel/sdk/trace"
+	semconv "go.opentelemetry.io/otel/semconv/v1.10.0"
 	"go.opentelemetry.io/otel/trace"
 )
 
@@ -80,6 +82,31 @@ func InitTracing(ctx context.Context, libraryName string, opts ...sdktrace.Trace
 	return tracerCtx, tracer, err
 }
 
+// NewResource creates a resource with sensible defaults.
+// Replaces common use case of verbose usage.
+func NewResource(serviceName, version string, resources ...*resource.Resource) (*resource.Resource, error) {
+	res, err := resource.Merge(
+		resource.Default(),
+		resource.NewWithAttributes(
+			semconv.SchemaURL,
+			semconv.ServiceNameKey.String(serviceName),
+			semconv.ServiceVersionKey.String(version),
+		),
+	)
+	if err != nil {
+		return nil, errors.Wrap(err, "error in resource.Merge")
+	}
+
+	for i, res2 := range resources {
+		res, err = resource.Merge(res, res2)
+		if err != nil {
+			return nil, errors.Wrapf(err, "error in resource.Merge on resources index %d", i)
+		}
+	}
+
+	return res, nil
+}
+
 // NewTracer instantiates a new `Tracer` object with a custom library name.
 // Must call `InitTracing()` first.
 // Library name is set in span attribute `otel.library.name`.