Fix using InstrumenterCustomizerProvider SPI in extensions

examples/distro/gradle/instrumentation.gradle

@@ -38,7 +38,7 @@ shadowJar {
 
   mergeServiceFiles()
   // mergeServiceFiles requires that duplicate strategy is set to include
-  filesMatching("inst/META-INF/services/**") {
+  filesMatching("META-INF/services/**") {
     duplicatesStrategy = DuplicatesStrategy.INCLUDE
   }
 

examples/extension/src/test/java/com/example/javaagent/smoketest/SpringBootIntegrationTest.java

@@ -87,5 +87,6 @@ private void testAndVerify() throws IOException, InterruptedException {
     Assertions.assertNotEquals(
         0, countResourcesByValue(traces, "telemetry.distro.version", currentAgentVersion));
     Assertions.assertNotEquals(0, countResourcesByValue(traces, "custom.resource", "demo"));
+    Assertions.assertEquals(1, countSpansByAttributeValue(traces, "demo.custom", "demo-extension"));
   }
 }

gradle-plugins/src/main/kotlin/io.opentelemetry.instrumentation.muzzle-check.gradle.kts

@@ -73,52 +73,54 @@ val shadowMuzzleBootstrap by tasks.registering(ShadowJar::class) {
 
 // this is a copied from io.opentelemetry.instrumentation.javaagent-shadowing for now at least to
 // avoid publishing io.opentelemetry.instrumentation.javaagent-shadowing publicly
-tasks.withType<ShadowJar>().configureEach {
-  mergeServiceFiles()
-  // mergeServiceFiles requires that duplicate strategy is set to include
-  filesMatching("META-INF/services/**") {
-    duplicatesStrategy = DuplicatesStrategy.INCLUDE
-  }
-  // Merge any AWS SDK service files that may be present (too bad they didn't just use normal
-  // service loader...)
-  mergeServiceFiles("software/amazon/awssdk/global/handlers")
-  // mergeServiceFiles requires that duplicate strategy is set to include
-  filesMatching("software/amazon/awssdk/global/handlers/**") {
-    duplicatesStrategy = DuplicatesStrategy.INCLUDE
-  }
+listOf(shadowModule, shadowMuzzleTooling, shadowMuzzleBootstrap).forEach { task ->
+  task.configure {
+    mergeServiceFiles()
+    // mergeServiceFiles requires that duplicate strategy is set to include
+    filesMatching("META-INF/services/**") {
+      duplicatesStrategy = DuplicatesStrategy.INCLUDE
+    }
+    // Merge any AWS SDK service files that may be present (too bad they didn't just use normal
+    // service loader...)
+    mergeServiceFiles("software/amazon/awssdk/global/handlers")
+    // mergeServiceFiles requires that duplicate strategy is set to include
+    filesMatching("software/amazon/awssdk/global/handlers/**") {
+      duplicatesStrategy = DuplicatesStrategy.INCLUDE
+    }
 
-  exclude("**/module-info.class")
+    exclude("**/module-info.class")
 
-  // rewrite dependencies calling Logger.getLogger
-  relocate("java.util.logging.Logger", "io.opentelemetry.javaagent.bootstrap.PatchLogger")
+    // rewrite dependencies calling Logger.getLogger
+    relocate("java.util.logging.Logger", "io.opentelemetry.javaagent.bootstrap.PatchLogger")
 
-  if (project.findProperty("disableShadowRelocate") != "true") {
-    // prevents conflict with library instrumentation, since these classes live in the bootstrap class loader
-    relocate("io.opentelemetry.instrumentation", "io.opentelemetry.javaagent.shaded.instrumentation") {
-      // Exclude resource providers since they live in the agent class loader
-      exclude("io.opentelemetry.instrumentation.resources.*")
-      exclude("io.opentelemetry.instrumentation.spring.resources.*")
-    }
+    if (project.findProperty("disableShadowRelocate") != "true") {
+      // prevents conflict with library instrumentation, since these classes live in the bootstrap class loader
+      relocate("io.opentelemetry.instrumentation", "io.opentelemetry.javaagent.shaded.instrumentation") {
+        // Exclude resource providers since they live in the agent class loader
+        exclude("io.opentelemetry.instrumentation.resources.*")
+        exclude("io.opentelemetry.instrumentation.spring.resources.*")
+      }
 
-    // relocate(OpenTelemetry API) since these classes live in the bootstrap class loader
-    relocate("io.opentelemetry.api", "io.opentelemetry.javaagent.shaded.io.opentelemetry.api")
-    relocate("io.opentelemetry.semconv", "io.opentelemetry.javaagent.shaded.io.opentelemetry.semconv")
-    relocate("io.opentelemetry.context", "io.opentelemetry.javaagent.shaded.io.opentelemetry.context")
-    relocate("io.opentelemetry.common", "io.opentelemetry.javaagent.shaded.io.opentelemetry.common")
-  }
+      // relocate(OpenTelemetry API) since these classes live in the bootstrap class loader
+      relocate("io.opentelemetry.api", "io.opentelemetry.javaagent.shaded.io.opentelemetry.api")
+      relocate("io.opentelemetry.semconv", "io.opentelemetry.javaagent.shaded.io.opentelemetry.semconv")
+      relocate("io.opentelemetry.context", "io.opentelemetry.javaagent.shaded.io.opentelemetry.context")
+      relocate("io.opentelemetry.common", "io.opentelemetry.javaagent.shaded.io.opentelemetry.common")
+    }
 
-  // relocate(the OpenTelemetry extensions that are used by instrumentation modules)
-  // these extensions live in the AgentClassLoader, and are injected into the user's class loader
-  // by the instrumentation modules that use them
-  relocate("io.opentelemetry.contrib.awsxray", "io.opentelemetry.javaagent.shaded.io.opentelemetry.contrib.awsxray")
-  relocate("io.opentelemetry.extension.kotlin", "io.opentelemetry.javaagent.shaded.io.opentelemetry.extension.kotlin")
+    // relocate(the OpenTelemetry extensions that are used by instrumentation modules)
+    // these extensions live in the AgentClassLoader, and are injected into the user's class loader
+    // by the instrumentation modules that use them
+    relocate("io.opentelemetry.contrib.awsxray", "io.opentelemetry.javaagent.shaded.io.opentelemetry.contrib.awsxray")
+    relocate("io.opentelemetry.extension.kotlin", "io.opentelemetry.javaagent.shaded.io.opentelemetry.extension.kotlin")
 
-  // this is for instrumentation of opentelemetry-api and opentelemetry-instrumentation-api
-  relocate("application.io.opentelemetry", "io.opentelemetry")
-  relocate("application.io.opentelemetry.instrumentation.api", "io.opentelemetry.instrumentation.api")
+    // this is for instrumentation of opentelemetry-api and opentelemetry-instrumentation-api
+    relocate("application.io.opentelemetry", "io.opentelemetry")
+    relocate("application.io.opentelemetry.instrumentation.api", "io.opentelemetry.instrumentation.api")
 
-  // this is for instrumentation on java.util.logging (since java.util.logging itself is shaded above)
-  relocate("application.java.util.logging", "java.util.logging")
+    // this is for instrumentation on java.util.logging (since java.util.logging itself is shaded above)
+    relocate("application.java.util.logging", "java.util.logging")
+  }
 }
 
 val compileMuzzle by tasks.registering {

javaagent-tooling/src/main/java/io/opentelemetry/javaagent/tooling/ExtensionClassLoader.java

@@ -25,6 +25,7 @@
 import java.util.Collections;
 import java.util.Enumeration;
 import java.util.List;
+import java.util.NoSuchElementException;
 import java.util.jar.JarEntry;
 import java.util.jar.JarFile;
 import javax.annotation.Nullable;
@@ -201,4 +202,50 @@ private ExtensionClassLoader(
     super(new URL[] {url}, parent);
     this.isSecurityManagerSupportEnabled = isSecurityManagerSupportEnabled;
   }
+
+  @Override
+  public Enumeration<URL> findResources(String name) throws IOException {
+    Enumeration<URL> result = super.findResources(name);
+    // Agent shades instrumentation-api-incubator, in extensions references to these classes are
+    // remapped at load time. Here we handle looking up the service files for the classes that
+    // were renamed using the original name.
+    if (name.startsWith(
+        "META-INF/services/io.opentelemetry.javaagent.shaded.instrumentation.api.incubator")) {
+      String originalName =
+          name.replace(
+              "opentelemetry.javaagent.shaded.instrumentation", "opentelemetry.instrumentation");
+      return new CompoundEnumeration<>(result, super.findResources(originalName));
+    }
+    return result;
+  }
+
+  private static class CompoundEnumeration<E> implements Enumeration<E> {
+    private final Enumeration<E>[] enumerations;
+    private int index = 0;
+
+    @SafeVarargs
+    @SuppressWarnings("varargs")
+    CompoundEnumeration(Enumeration<E>... enumerations) {
+      this.enumerations = enumerations;
+    }
+
+    @Override
+    public boolean hasMoreElements() {
+      while (index < enumerations.length) {
+        if (enumerations[index].hasMoreElements()) {
+          return true;
+        }
+        index++;
+      }
+      return false;
+    }
+
+    @Override
+    public E nextElement() {
+      if (!hasMoreElements()) {
+        throw new NoSuchElementException();
+      }
+      return enumerations[index].nextElement();
+    }
+  }
 }