Fix "Class path contains multiple SLF4J bindings" during runtime atta… (#380)

* Fix "Class path contains multiple SLF4J bindings" during runtime attachment

* Update runtime-attach/build.gradle.kts

Co-authored-by: Trask Stalnaker <trask.stalnaker@gmail.com>

* Renaming

Co-authored-by: Trask Stalnaker <trask.stalnaker@gmail.com>

runtime-attach-core/README.md

@@ -0,0 +1,5 @@
+# Runtime attachment core
+
+This project is dedicated to providers of the [OpenTelemetry Java agent](https://github.com/open-telemetry/opentelemetry-java-instrumentation). It helps them to build a dependency to runtime attach their agent jar file.
+
+You can find [here](../runtime-attach/README.md) the project of the distribution published by OpenTelemetry.

runtime-attach-core/build.gradle.kts

@@ -0,0 +1,13 @@
+plugins {
+  id("otel.java-conventions")
+  id("otel.publish-conventions")
+}
+
+description = "To help in create an OpenTelemetry distro able to runtime attach an OpenTelemetry Java Instrumentation agent"
+
+dependencies {
+  implementation("net.bytebuddy:byte-buddy-agent:1.11.18")
+
+  // Used by byte-buddy but not brought in as a transitive dependency.
+  compileOnly("com.google.code.findbugs:annotations")
+}

runtime-attach-core/src/main/java/io/opentelemetry/contrib/attach/AgentFileProvider.java

@@ -5,24 +5,25 @@
 
 package io.opentelemetry.contrib.attach;
 
-import io.opentelemetry.javaagent.OpenTelemetryAgent;
 import java.io.File;
 import java.io.IOException;
 import java.io.InputStream;
-import java.net.URL;
 import java.nio.file.Files;
 import java.nio.file.Path;
-import java.security.CodeSource;
 
 final class AgentFileProvider {
 
-  static File getAgentFile() {
+  private final String agentJarResourceName;
 
-    verifyExistenceOfAgentJarFile();
+  AgentFileProvider(String agentJarResourceName) {
+    this.agentJarResourceName = agentJarResourceName;
+  }
+
+  File getAgentFile() {
 
     Path tempDirPath = createTempDir();
 
-    Path tempAgentJarPath = createTempAgentJarFile(tempDirPath);
+    Path tempAgentJarPath = createTempAgentJarFileIn(tempDirPath);
 
     deleteTempDirOnJvmExit(tempDirPath, tempAgentJarPath);
 
@@ -34,13 +35,6 @@ final class AgentFileProvider {
     tempDirPath.toFile().deleteOnExit();
   }
 
-  private static void verifyExistenceOfAgentJarFile() {
-    CodeSource codeSource = OpenTelemetryAgent.class.getProtectionDomain().getCodeSource();
-    if (codeSource == null) {
-      throw new IllegalStateException("could not get agent jar location");
-    }
-  }
-
   private static Path createTempDir() {
     Path tempDir;
     try {
@@ -51,23 +45,18 @@ final class AgentFileProvider {
     return tempDir;
   }
 
-  private static Path createTempAgentJarFile(Path tempDir) {
-    URL url = OpenTelemetryAgent.class.getProtectionDomain().getCodeSource().getLocation();
-    try {
-      return copyTo(url, tempDir, "agent.jar");
+  private Path createTempAgentJarFileIn(Path tempDir) {
+    Path agentJarPath = tempDir.resolve("agent.jar");
+    try (InputStream jarAsInputStream =
+        AgentFileProvider.class.getResourceAsStream(this.agentJarResourceName)) {
+      if (jarAsInputStream == null) {
+        throw new IllegalStateException(this.agentJarResourceName + " resource can't be found");
+      }
+      Files.copy(jarAsInputStream, agentJarPath);
     } catch (IOException e) {
       throw new IllegalStateException(
           "Runtime attachment can't create agent jar file in temp directory", e);
     }
+    return agentJarPath;
   }
-
-  private static Path copyTo(URL url, Path tempDir, String fileName) throws IOException {
-    Path tempFile = tempDir.resolve(fileName);
-    try (InputStream in = url.openStream()) {
-      Files.copy(in, tempFile);
-    }
-    return tempFile;
-  }
-
-  private AgentFileProvider() {}
 }

runtime-attach-core/src/main/java/io/opentelemetry/contrib/attach/CoreRuntimeAttach.java

@@ -0,0 +1,124 @@
+/*
+ * Copyright The OpenTelemetry Authors
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+package io.opentelemetry.contrib.attach;
+
+import java.io.File;
+import java.lang.management.ManagementFactory;
+import net.bytebuddy.agent.ByteBuddyAgent;
+
+/** This class allows you to attach the OpenTelemetry Java agent at runtime. */
+public final class CoreRuntimeAttach {
+
+  private static final String AGENT_ENABLED_PROPERTY = "otel.javaagent.enabled";
+  private static final String AGENT_ENABLED_ENV_VAR = "OTEL_JAVAAGENT_ENABLED";
+  static final String MAIN_METHOD_CHECK_PROP =
+      "otel.javaagent.testing.runtime-attach.main-method-check";
+
+  private final String agentJarResourceName;
+
+  /**
+   * Creates a new {@code DistroRuntimeAttach} from the resource name of the agent jar.
+   *
+   * @param agentJarResourceName Resource name of the agent jar.
+   */
+  public CoreRuntimeAttach(String agentJarResourceName) {
+    this.agentJarResourceName = agentJarResourceName;
+  }
+
+  /**
+   * Attach the OpenTelemetry Java agent to the current JVM. The attachment must be requested at the
+   * beginning of the main method.
+   */
+  public void attachJavaagentToCurrentJVM() {
+    if (!shouldAttach()) {
+      return;
+    }
+
+    AgentFileProvider agentFileProvider = new AgentFileProvider(agentJarResourceName);
+
+    File javaagentFile = agentFileProvider.getAgentFile();
+    ByteBuddyAgent.attach(javaagentFile, getPid());
+
+    if (!agentIsAttached()) {
+      printError("Agent was not attached. An unexpected issue has happened.");
+    }
+  }
+
+  @SuppressWarnings("SystemOut")
+  private static void printError(String message) {
+    // not using java.util.logging in order to avoid initializing the global LogManager
+    // too early (and incompatibly with the user's app),
+    // and because this is too early to use the Javaagent's PatchLogger
+    System.err.println(message);
+  }
+
+  private static boolean shouldAttach() {
+    if (agentIsDisabledWithProp()) {
+      return false;
+    }
+    if (agentIsDisabledWithEnvVar()) {
+      return false;
+    }
+    if (agentIsAttached()) {
+      return false;
+    }
+    if (mainMethodCheckIsEnabled() && !isMainThread()) {
+      printError(
+          "Agent is not attached because runtime attachment was not requested from main thread.");
+      return false;
+    }
+    if (mainMethodCheckIsEnabled() && !isMainMethod()) {
+      printError(
+          "Agent is not attached because runtime attachment was not requested from main method.");
+      return false;
+    }
+    return true;
+  }
+
+  private static boolean agentIsDisabledWithProp() {
+    String agentEnabledPropValue = System.getProperty(AGENT_ENABLED_PROPERTY);
+    return "false".equalsIgnoreCase(agentEnabledPropValue);
+  }
+
+  private static boolean agentIsDisabledWithEnvVar() {
+    String agentEnabledEnvVarValue = System.getenv(AGENT_ENABLED_ENV_VAR);
+    return "false".equals(agentEnabledEnvVarValue);
+  }
+
+  private static boolean agentIsAttached() {
+    try {
+      Class.forName("io.opentelemetry.javaagent.OpenTelemetryAgent", false, null);
+      return true;
+    } catch (ClassNotFoundException e) {
+      return false;
+    }
+  }
+
+  private static boolean mainMethodCheckIsEnabled() {
+    String mainThreadCheck = System.getProperty(MAIN_METHOD_CHECK_PROP);
+    return !"false".equals(mainThreadCheck);
+  }
+
+  private static boolean isMainThread() {
+    Thread currentThread = Thread.currentThread();
+    return "main".equals(currentThread.getName());
+  }
+
+  static boolean isMainMethod() {
+    StackTraceElement bottomOfStack = findBottomOfStack(Thread.currentThread());
+    String methodName = bottomOfStack.getMethodName();
+    return "main".equals(methodName);
+  }
+
+  private static StackTraceElement findBottomOfStack(Thread thread) {
+    StackTraceElement[] stackTrace = thread.getStackTrace();
+    return stackTrace[stackTrace.length - 1];
+  }
+
+  private static String getPid() {
+    return ManagementFactory.getRuntimeMXBean().getName().split("@")[0];
+  }
+}

runtime-attach/build.gradle.kts

@@ -3,11 +3,13 @@ plugins {
   id("otel.publish-conventions")
 }
 
-description = "Utility to attach OpenTelemetry Java Instrumentation agent from classpath"
+description = "To runtime attach the OpenTelemetry Java Instrumentation agent"
+
+val agent: Configuration by configurations.creating
 
 dependencies {
-  compileOnly("io.opentelemetry.javaagent:opentelemetry-javaagent:1.6.0")
-  implementation("net.bytebuddy:byte-buddy-agent:1.11.18")
+  implementation(project(":runtime-attach-core"))
+  agent("io.opentelemetry.javaagent:opentelemetry-javaagent:1.15.0")
 
   // Used by byte-buddy but not brought in as a transitive dependency.
   compileOnly("com.google.code.findbugs:annotations")
@@ -23,3 +25,13 @@ tasks.test {
   useJUnitPlatform()
   setForkEvery(1) // One JVM by test class to avoid a test class launching a runtime attachment influences the behavior of another test class
 }
+
+tasks {
+  jar {
+    inputs.files(agent)
+    from({
+      agent.singleFile
+    })
+    rename { "otel-agent.jar" }
+  }
+}

runtime-attach/src/main/java/io/opentelemetry/contrib/attach/RuntimeAttach.java

@@ -5,108 +5,18 @@
 
 package io.opentelemetry.contrib.attach;
 
-import java.io.File;
-import java.lang.management.ManagementFactory;
-import net.bytebuddy.agent.ByteBuddyAgent;
-
 /** This class allows you to attach the OpenTelemetry Java agent at runtime. */
 public final class RuntimeAttach {
 
-  private static final String AGENT_ENABLED_PROPERTY = "otel.javaagent.enabled";
-  private static final String AGENT_ENABLED_ENV_VAR = "OTEL_JAVAAGENT_ENABLED";
-  static final String MAIN_METHOD_CHECK_PROP =
-      "otel.javaagent.testing.runtime-attach.main-method-check";
-
   /**
    * Attach the OpenTelemetry Java agent to the current JVM. The attachment must be requested at the
    * beginning of the main method.
    */
   public static void attachJavaagentToCurrentJVM() {
-    if (!shouldAttach()) {
-      return;
-    }
 
-    File javaagentFile = AgentFileProvider.getAgentFile();
-    ByteBuddyAgent.attach(javaagentFile, getPid());
+    CoreRuntimeAttach distroRuntimeAttach = new CoreRuntimeAttach("/otel-agent.jar");
 
-    if (!agentIsAttached()) {
-      printError("Agent was not attached. An unexpected issue has happened.");
-    }
-  }
-
-  @SuppressWarnings("SystemOut")
-  private static void printError(String message) {
-    // not using java.util.logging in order to avoid initializing the global LogManager
-    // too early (and incompatibly with the user's app),
-    // and because this is too early to use the Javaagent's PatchLogger
-    System.err.println(message);
-  }
-
-  private static boolean shouldAttach() {
-    if (agentIsDisabledWithProp()) {
-      return false;
-    }
-    if (agentIsDisabledWithEnvVar()) {
-      return false;
-    }
-    if (agentIsAttached()) {
-      return false;
-    }
-    if (mainMethodCheckIsEnabled() && !isMainThread()) {
-      printError(
-          "Agent is not attached because runtime attachment was not requested from main thread.");
-      return false;
-    }
-    if (mainMethodCheckIsEnabled() && !isMainMethod()) {
-      printError(
-          "Agent is not attached because runtime attachment was not requested from main method.");
-      return false;
-    }
-    return true;
-  }
-
-  private static boolean agentIsDisabledWithProp() {
-    String agentEnabledPropValue = System.getProperty(AGENT_ENABLED_PROPERTY);
-    return "false".equalsIgnoreCase(agentEnabledPropValue);
-  }
-
-  private static boolean agentIsDisabledWithEnvVar() {
-    String agentEnabledEnvVarValue = System.getenv(AGENT_ENABLED_ENV_VAR);
-    return "false".equals(agentEnabledEnvVarValue);
-  }
-
-  private static boolean agentIsAttached() {
-    try {
-      Class.forName("io.opentelemetry.javaagent.OpenTelemetryAgent", false, null);
-      return true;
-    } catch (ClassNotFoundException e) {
-      return false;
-    }
-  }
-
-  private static boolean mainMethodCheckIsEnabled() {
-    String mainThreadCheck = System.getProperty(MAIN_METHOD_CHECK_PROP);
-    return !"false".equals(mainThreadCheck);
-  }
-
-  private static boolean isMainThread() {
-    Thread currentThread = Thread.currentThread();
-    return "main".equals(currentThread.getName());
-  }
-
-  static boolean isMainMethod() {
-    StackTraceElement bottomOfStack = findBottomOfStack(Thread.currentThread());
-    String methodName = bottomOfStack.getMethodName();
-    return "main".equals(methodName);
-  }
-
-  private static StackTraceElement findBottomOfStack(Thread thread) {
-    StackTraceElement[] stackTrace = thread.getStackTrace();
-    return stackTrace[stackTrace.length - 1];
-  }
-
-  private static String getPid() {
-    return ManagementFactory.getRuntimeMXBean().getName().split("@")[0];
+    distroRuntimeAttach.attachJavaagentToCurrentJVM();
   }
 
   private RuntimeAttach() {}

runtime-attach/src/test/java/io/opentelemetry/contrib/attach/AbstractAttachmentTest.java

@@ -12,7 +12,7 @@ public class AbstractAttachmentTest {
 
   @BeforeAll
   static void disableMainThreadCheck() {
-    System.setProperty(RuntimeAttach.MAIN_METHOD_CHECK_PROP, "false");
+    System.setProperty(CoreRuntimeAttach.MAIN_METHOD_CHECK_PROP, "false");
   }
 
   boolean isAttached() {

settings.gradle.kts

@@ -47,6 +47,7 @@ include(":micrometer-meter-provider")
 include(":jmx-metrics")
 include(":maven-extension")
 include(":runtime-attach")
+include(":runtime-attach-core")
 include(":samplers")
 include(":static-instrumenter:agent-instrumenter")
 include(":static-instrumenter:gradle-plugin")