Add Telemetry for Extension Finder SPIs

dd-java-agent/agent-installer/src/main/java/datadog/trace/agent/tooling/ExtensionFinder.java

@@ -3,6 +3,7 @@
 import static datadog.opentelemetry.tooling.OtelExtensionHandler.OPENTELEMETRY;
 import static datadog.trace.agent.tooling.ExtensionHandler.DATADOG;
 
+import datadog.trace.api.telemetry.OtelSpiCollector;
 import de.thetaphi.forbiddenapis.SuppressForbidden;
 import java.io.File;
 import java.io.FileNotFoundException;
@@ -13,6 +14,7 @@
 import java.net.URLConnection;
 import java.net.URLStreamHandler;
 import java.util.ArrayList;
+import java.util.Enumeration;
 import java.util.List;
 import java.util.jar.JarEntry;
 import java.util.jar.JarFile;
@@ -26,6 +28,11 @@ public final class ExtensionFinder {
 
   private static final ExtensionHandler[] handlers = {OPENTELEMETRY, DATADOG};
 
+  private static final String EXTENSIONS_PATH_SOURCE = "extensions_path";
+
+  private static final String SERVICES_PREFIX = "META-INF/services/";
+  private static final String OTEL_NAMESPACE = "io.opentelemetry.";
+
   /**
    * Discovers extensions on the configured path and creates a classloader for each extension.
    * Registers the combined classloader with {@link Utils#setExtendedClassLoader(ClassLoader)}.
@@ -40,6 +47,7 @@ public static boolean findExtensions(String extensionsPath, Class<?>... extensio
     String[] descriptors = descriptors(extensionTypes);
 
     for (JarFile jar : findExtensionJars(extensionsPath)) {
+      recordOtelSpiTelemetry(jar);
       URL extensionURL = findExtensionURL(jar, descriptors);
       if (null != extensionURL) {
         log.debug("Found extension jar {}", jar.getName());
@@ -60,6 +68,24 @@ public static boolean findExtensions(String extensionsPath, Class<?>... extensio
     return !classLoaders.isEmpty();
   }
 
+  /**
+   * Reports telemetry for any OpenTelemetry SPI service descriptors present in the jar — any entry
+   * under {@code META-INF/services/} whose name lives in the {@code io.opentelemetry.*} namespace.
+   * The jar's existing handle is reused; no new file resources are opened or held.
+   */
+  static void recordOtelSpiTelemetry(JarFile jar) {
+    Enumeration<JarEntry> entries = jar.entries();
+    while (entries.hasMoreElements()) {
+      String name = entries.nextElement().getName();
+      if (name.startsWith(SERVICES_PREFIX)) {
+        String fqn = name.substring(SERVICES_PREFIX.length());
+        if (fqn.startsWith(OTEL_NAMESPACE)) {
+          OtelSpiCollector.getInstance().recordSpiDetected(fqn, EXTENSIONS_PATH_SOURCE);
+        }
+      }
+    }
+  }
+
   /** Closes jar resources from the extension path which did not contain any extensions. */
   private static void close(List<JarFile> unusedJars) {
     for (JarFile jar : unusedJars) {

dd-java-agent/agent-installer/src/test/java/datadog/trace/agent/tooling/ExtensionFinderTest.java

@@ -0,0 +1,193 @@
+package datadog.trace.agent.tooling;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+import datadog.trace.api.telemetry.OtelSpiCollector;
+import java.io.IOException;
+import java.io.OutputStream;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.util.Collection;
+import java.util.HashSet;
+import java.util.Set;
+import java.util.jar.JarEntry;
+import java.util.jar.JarFile;
+import java.util.jar.JarOutputStream;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.io.TempDir;
+
+public class ExtensionFinderTest {
+
+  private static final String AUTOCONFIGURE_PROPAGATOR =
+      "io.opentelemetry.sdk.autoconfigure.spi.ConfigurablePropagatorProvider";
+  private static final String AUTOCONFIGURE_RESOURCE =
+      "io.opentelemetry.sdk.autoconfigure.spi.ResourceProvider";
+  private static final String AUTOCONFIGURE_SAMPLER =
+      "io.opentelemetry.sdk.autoconfigure.spi.ConfigurableSamplerProvider";
+  private static final String AUTOCONFIGURE_EXPORTER =
+      "io.opentelemetry.sdk.autoconfigure.spi.traces.ConfigurableSpanExporterProvider";
+  private static final String JAVAAGENT_INSTRUMENTATION_MODULE =
+      "io.opentelemetry.javaagent.extension.instrumentation.InstrumentationModule";
+  private static final String JAVAAGENT_AGENT_LISTENER =
+      "io.opentelemetry.javaagent.extension.AgentListener";
+  private static final String SHADED_AUTOCONFIGURE_SAMPLER =
+      "io.opentelemetry.javaagent.shaded.io.opentelemetry.sdk.autoconfigure.spi.ConfigurableSamplerProvider";
+
+  private final OtelSpiCollector collector = OtelSpiCollector.getInstance();
+
+  @BeforeEach
+  public void clearCollector() {
+    collector.drain();
+  }
+
+  @Test
+  public void singleOtelSpiIsReported(@TempDir Path tempDir) throws IOException {
+    Path jarPath = buildJar(tempDir, "ext.jar", AUTOCONFIGURE_PROPAGATOR);
+
+    try (JarFile jar = new JarFile(jarPath.toFile(), false)) {
+      ExtensionFinder.recordOtelSpiTelemetry(jar);
+    }
+
+    Collection<OtelSpiCollector.OtelSpiMetric> drained = collector.drain();
+    assertEquals(1, drained.size());
+    OtelSpiCollector.OtelSpiMetric metric = drained.iterator().next();
+    assertEquals("otel.spi.detected", metric.metricName);
+    assertTrue(metric.tags.contains("spi_class:" + AUTOCONFIGURE_PROPAGATOR));
+    assertTrue(metric.tags.contains("source:extensions_path"));
+  }
+
+  @Test
+  public void allFourAutoconfigureSpisAreReported(@TempDir Path tempDir) throws IOException {
+    Path jarPath =
+        buildJar(
+            tempDir,
+            "ext.jar",
+            AUTOCONFIGURE_PROPAGATOR,
+            AUTOCONFIGURE_RESOURCE,
+            AUTOCONFIGURE_SAMPLER,
+            AUTOCONFIGURE_EXPORTER);
+
+    try (JarFile jar = new JarFile(jarPath.toFile(), false)) {
+      ExtensionFinder.recordOtelSpiTelemetry(jar);
+    }
+
+    assertEquals(
+        new HashSet<>(
+            java.util.Arrays.asList(
+                AUTOCONFIGURE_PROPAGATOR,
+                AUTOCONFIGURE_RESOURCE,
+                AUTOCONFIGURE_SAMPLER,
+                AUTOCONFIGURE_EXPORTER)),
+        reportedFqns(collector.drain()));
+  }
+
+  @Test
+  public void javaagentExtensionSpisAreReported(@TempDir Path tempDir) throws IOException {
+    Path jarPath =
+        buildJar(tempDir, "ext.jar", JAVAAGENT_INSTRUMENTATION_MODULE, JAVAAGENT_AGENT_LISTENER);
+
+    try (JarFile jar = new JarFile(jarPath.toFile(), false)) {
+      ExtensionFinder.recordOtelSpiTelemetry(jar);
+    }
+
+    assertEquals(
+        new HashSet<>(
+            java.util.Arrays.asList(JAVAAGENT_INSTRUMENTATION_MODULE, JAVAAGENT_AGENT_LISTENER)),
+        reportedFqns(collector.drain()));
+  }
+
+  @Test
+  public void shadedJavaagentSpiIsReported(@TempDir Path tempDir) throws IOException {
+    Path jarPath = buildJar(tempDir, "ext.jar", SHADED_AUTOCONFIGURE_SAMPLER);
+
+    try (JarFile jar = new JarFile(jarPath.toFile(), false)) {
+      ExtensionFinder.recordOtelSpiTelemetry(jar);
+    }
+
+    Collection<OtelSpiCollector.OtelSpiMetric> drained = collector.drain();
+    assertEquals(1, drained.size());
+    assertTrue(
+        drained.iterator().next().tags.contains("spi_class:" + SHADED_AUTOCONFIGURE_SAMPLER));
+  }
+
+  @Test
+  public void nonOtelSpiIsIgnored(@TempDir Path tempDir) throws IOException {
+    Path jarPath =
+        buildJar(
+            tempDir,
+            "ext.jar",
+            "com.example.MyService",
+            "org.springframework.context.ApplicationContextInitializer",
+            "java.sql.Driver");
+
+    try (JarFile jar = new JarFile(jarPath.toFile(), false)) {
+      ExtensionFinder.recordOtelSpiTelemetry(jar);
+    }
+
+    assertEquals(0, collector.drain().size());
+  }
+
+  @Test
+  public void jarWithoutAnyServiceDescriptorsEmitsNothing(@TempDir Path tempDir)
+      throws IOException {
+    Path jarPath = tempDir.resolve("empty.jar");
+    try (JarOutputStream jos = new JarOutputStream(Files.newOutputStream(jarPath))) {
+      jos.putNextEntry(new JarEntry("README.txt"));
+      jos.write("not an extension".getBytes());
+      jos.closeEntry();
+    }
+
+    try (JarFile jar = new JarFile(jarPath.toFile(), false)) {
+      ExtensionFinder.recordOtelSpiTelemetry(jar);
+    }
+
+    assertEquals(0, collector.drain().size());
+  }
+
+  @Test
+  public void mixedOtelAndNonOtelReportsOnlyOtel(@TempDir Path tempDir) throws IOException {
+    Path jarPath =
+        buildJar(
+            tempDir,
+            "ext.jar",
+            AUTOCONFIGURE_PROPAGATOR,
+            "com.example.MyService",
+            JAVAAGENT_AGENT_LISTENER,
+            "java.sql.Driver");
+
+    try (JarFile jar = new JarFile(jarPath.toFile(), false)) {
+      ExtensionFinder.recordOtelSpiTelemetry(jar);
+    }
+
+    assertEquals(
+        new HashSet<>(java.util.Arrays.asList(AUTOCONFIGURE_PROPAGATOR, JAVAAGENT_AGENT_LISTENER)),
+        reportedFqns(collector.drain()));
+  }
+
+  private static Set<String> reportedFqns(Collection<OtelSpiCollector.OtelSpiMetric> drained) {
+    Set<String> fqns = new HashSet<>();
+    for (OtelSpiCollector.OtelSpiMetric metric : drained) {
+      for (String tag : metric.tags) {
+        if (tag.startsWith("spi_class:")) {
+          fqns.add(tag.substring("spi_class:".length()));
+        }
+      }
+    }
+    return fqns;
+  }
+
+  /** Builds a jar with empty {@code META-INF/services/<fqn>} entries for each given FQN. */
+  private static Path buildJar(Path dir, String name, String... serviceFqns) throws IOException {
+    Path jarPath = dir.resolve(name);
+    try (OutputStream out = Files.newOutputStream(jarPath);
+        JarOutputStream jos = new JarOutputStream(out)) {
+      for (String fqn : serviceFqns) {
+        jos.putNextEntry(new JarEntry("META-INF/services/" + fqn));
+        jos.closeEntry();
+      }
+    }
+    return jarPath;
+  }
+}