feat(node-sdk): add spanProcessors option

Since span processors can be chained together, it makes sense to expose
this option as an array of span processors. This change also deprecates
the `spanProcessor` option in favor of `spanProcessors`.

experimental/packages/opentelemetry-sdk-node/README.md

@@ -124,6 +124,12 @@ Configure a custom sampler. By default, all traces will be sampled.
 
 ### spanProcessor
 
+Deprecated, please use [`spanProcessors](#spanprocessors) instead.
+
+### spanProcessors
+
+An array of span processors to register to the tracer provider.
+
 ### traceExporter
 
 Configure a trace exporter. If an exporter is configured, it will be used with a [BatchSpanProcessor](../../../packages/opentelemetry-sdk-trace-base/src/platform/node/export/BatchSpanProcessor.ts). If an exporter OR span processor is not configured programatically, this package will auto setup the default `otlp` exporter  with `http/protobuf` protocol with a `BatchSpanProcessor`.

experimental/packages/opentelemetry-sdk-node/src/sdk.ts

@@ -75,7 +75,7 @@ export type LoggerProviderConfig = {
 export class NodeSDK {
   private _tracerProviderConfig?: {
     tracerConfig: NodeTracerConfig;
-    spanProcessor: SpanProcessor;
+    spanProcessors: SpanProcessor[];
     contextManager?: ContextManager;
     textMapPropagator?: TextMapPropagator;
   };
@@ -147,9 +147,11 @@ export class NodeSDK {
         configuration.spanProcessor ??
         new BatchSpanProcessor(configuration.traceExporter!);
 
+      const spanProcessors = configuration.spanProcessors ?? [spanProcessor];
+
       this.configureTracerProvider(
         tracerProviderConfig,
-        spanProcessor,
+        spanProcessors,
         configuration.contextManager,
         configuration.textMapPropagator
       );
@@ -192,13 +194,13 @@ export class NodeSDK {
    */
   public configureTracerProvider(
     tracerConfig: NodeTracerConfig,
-    spanProcessor: SpanProcessor,
+    spanProcessors: SpanProcessor[],
     contextManager?: ContextManager,
     textMapPropagator?: TextMapPropagator
   ): void {
     this._tracerProviderConfig = {
       tracerConfig,
-      spanProcessor,
+      spanProcessors,
       contextManager,
       textMapPropagator,
     };
@@ -334,7 +336,9 @@ export class NodeSDK {
     this._tracerProvider = tracerProvider;
 
     if (this._tracerProviderConfig) {
-      tracerProvider.addSpanProcessor(this._tracerProviderConfig.spanProcessor);
+      for (const spanProcessor of this._tracerProviderConfig.spanProcessors) {
+        tracerProvider.addSpanProcessor(spanProcessor);
+      }
     }
 
     tracerProvider.register({

experimental/packages/opentelemetry-sdk-node/src/types.ts

@@ -40,7 +40,9 @@ export interface NodeSDKConfiguration {
   resourceDetectors: Array<Detector | DetectorSync>;
   sampler: Sampler;
   serviceName?: string;
-  spanProcessor: SpanProcessor;
+  /** @deprecated use spanProcessors instead*/
+  spanProcessor?: SpanProcessor;
+  spanProcessors?: SpanProcessor[];
   traceExporter: SpanExporter;
   spanLimits: SpanLimits;
   idGenerator: IdGenerator;

experimental/packages/opentelemetry-sdk-node/test/sdk.test.ts

@@ -200,12 +200,15 @@ describe('Node SDK', () => {
       delete env.OTEL_TRACES_EXPORTER;
     });
 
-    it('should register a tracer provider if a span processor is provided', async () => {
+    it('should register a tracer provider if a span processors are provided', async () => {
       const exporter = new ConsoleSpanExporter();
-      const spanProcessor = new SimpleSpanProcessor(exporter);
 
       const sdk = new NodeSDK({
-        spanProcessor,
+        spanProcessors: [
+          new NoopSpanProcessor(),
+          new SimpleSpanProcessor(exporter),
+          new BatchSpanProcessor(exporter),
+        ],
         autoDetectResources: false,
       });
 
@@ -223,6 +226,16 @@ describe('Node SDK', () => {
       const apiTracerProvider =
         trace.getTracerProvider() as ProxyTracerProvider;
       assert.ok(apiTracerProvider.getDelegate() instanceof NodeTracerProvider);
+
+
+      const listOfProcessors =
+      sdk['_tracerProvider']!['_registeredSpanProcessors']!;
+
+      assert(sdk['_tracerProvider'] instanceof TracerProviderWithEnvExporters);
+      assert(listOfProcessors.length === 3);
+      assert(listOfProcessors[0] instanceof NoopSpanProcessor);
+      assert(listOfProcessors[1] instanceof SimpleSpanProcessor);
+      assert(listOfProcessors[2] instanceof BatchSpanProcessor);
     });
 
     it('should register a meter provider if a reader is provided', async () => {