configure spring OTLP exporter without using internal classes

spring-native/README.md

@@ -12,6 +12,8 @@ The example uses the following elements:
   and exporting to the standard output with
   the [logging exporter](https://github.com/open-telemetry/opentelemetry-collector/tree/main/exporter/loggingexporter).
 - A spring configuration to suppress spans for the `/actuator` endpoint
+- A spring configuration to set OTLP headers dynamically 
+  (not needed for the example - it shows how to configure exporters programmatically)
 
 # Description of the instrumentation set-up
 

spring-native/src/main/java/io/opentelemetry/example/graal/Application.java

@@ -1,27 +1,12 @@
 package io.opentelemetry.example.graal;
 
-import io.opentelemetry.api.trace.SpanKind;
-import io.opentelemetry.contrib.sampler.RuleBasedRoutingSampler;
-import io.opentelemetry.sdk.autoconfigure.spi.AutoConfigurationCustomizerProvider;
-import io.opentelemetry.semconv.SemanticAttributes;
 import org.springframework.boot.SpringApplication;
 import org.springframework.boot.autoconfigure.SpringBootApplication;
-import org.springframework.context.annotation.Bean;
 
 @SpringBootApplication
 public class Application {
 
   public static void main(String[] args) {
     SpringApplication.run(Application.class, args);
   }
-
-  @Bean
-  public AutoConfigurationCustomizerProvider otelCustomizer() {
-    return p ->
-        p.addSamplerCustomizer(
-            (fallback, c) ->
-                RuleBasedRoutingSampler.builder(SpanKind.SERVER, fallback)
-                    .drop(SemanticAttributes.URL_PATH, "^/actuator")
-                    .build());
-  }
 }

spring-native/src/main/java/io/opentelemetry/example/graal/OpenTelemetryConfig.java

@@ -0,0 +1,52 @@
+package io.opentelemetry.example.graal;
+
+import io.opentelemetry.api.trace.SpanKind;
+import io.opentelemetry.contrib.sampler.RuleBasedRoutingSampler;
+import io.opentelemetry.exporter.otlp.http.trace.OtlpHttpSpanExporter;
+import io.opentelemetry.sdk.autoconfigure.spi.AutoConfigurationCustomizerProvider;
+import io.opentelemetry.sdk.autoconfigure.spi.ConfigProperties;
+import io.opentelemetry.sdk.trace.export.SpanExporter;
+import io.opentelemetry.sdk.trace.samplers.Sampler;
+import io.opentelemetry.semconv.SemanticAttributes;
+import java.util.Collections;
+import java.util.Map;
+import org.springframework.context.annotation.Bean;
+import org.springframework.context.annotation.Configuration;
+
+@Configuration
+public class OpenTelemetryConfig {
+
+  @Bean
+  public AutoConfigurationCustomizerProvider otelCustomizer() {
+    return p ->
+        p.addSamplerCustomizer(this::configureSampler)
+            .addSpanExporterCustomizer(this::configureSpanExporter);
+  }
+
+  /** suppress spans for actuator endpoints */
+  private RuleBasedRoutingSampler configureSampler(Sampler fallback, ConfigProperties config) {
+    return RuleBasedRoutingSampler.builder(SpanKind.SERVER, fallback)
+        .drop(SemanticAttributes.URL_PATH, "^/actuator")
+        .build();
+  }
+
+  /**
+   * Configuration for the OTLP exporter. This configuration will replace the default OTLP exporter,
+   * and will add a custom header to the requests.
+   */
+  private SpanExporter configureSpanExporter(SpanExporter exporter, ConfigProperties config) {
+    if (exporter instanceof OtlpHttpSpanExporter) {
+      return ((OtlpHttpSpanExporter) exporter).toBuilder().setHeaders(this::headers).build();
+    }
+    return exporter;
+  }
+
+  private Map<String, String> headers() {
+    return Collections.singletonMap("Authorization", "Bearer " + refreshToken());
+  }
+
+  private String refreshToken() {
+    // e.g. read the token from a kubernetes secret
+    return "token";
+  }
+}