Fix "URI is not hierarchical" during runtime attachment (#359)

* Fix "java.lang.IllegalArgumentException: URI is not hierarchical" during runtime attachment

* Fix build issue

* Fiw file creation and deletion

* Add null checks

* Only delete jar file on JVM exit

* Fix merge

* Fix spotless

* Remove null checks

* Spotless

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

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

@@ -1,38 +0,0 @@
-/*
- * Copyright The OpenTelemetry Authors
- * SPDX-License-Identifier: Apache-2.0
- */
-
-package io.opentelemetry.contrib.attach;
-
-import io.opentelemetry.javaagent.OpenTelemetryAgent;
-import java.io.File;
-import java.net.URISyntaxException;
-import java.net.URL;
-import java.security.CodeSource;
-
-final class AgentFileLocator {
-
-  static File locateAgentFile() {
-    CodeSource codeSource = OpenTelemetryAgent.class.getProtectionDomain().getCodeSource();
-
-    if (codeSource == null) {
-      throw new IllegalStateException("could not get agent jar location");
-    }
-
-    URL codeSourceLocation = codeSource.getLocation();
-    try {
-      File javaagentFile = new File(codeSourceLocation.toURI());
-      if (javaagentFile.isFile()) {
-        return javaagentFile;
-      }
-    } catch (URISyntaxException ignored) {
-      // ignored
-    }
-
-    throw new IllegalStateException(
-        "agent jar location doesn't appear to be a file: " + codeSourceLocation);
-  }
-
-  private AgentFileLocator() {}
-}

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

@@ -0,0 +1,73 @@
+/*
+ * Copyright The OpenTelemetry Authors
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+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() {
+
+    verifyExistenceOfAgentJarFile();
+
+    Path tempDirPath = createTempDir();
+
+    Path tempAgentJarPath = createTempAgentJarFile(tempDirPath);
+
+    deleteTempDirOnJvmExit(tempDirPath, tempAgentJarPath);
+
+    return tempAgentJarPath.toFile();
+  }
+
+  private static void deleteTempDirOnJvmExit(Path tempDirPath, Path tempAgentJarPath) {
+    tempAgentJarPath.toFile().deleteOnExit();
+    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 {
+      tempDir = Files.createTempDirectory("otel-agent");
+    } catch (IOException e) {
+      throw new IllegalStateException("Runtime attachment can't create temp directory", e);
+    }
+    return tempDir;
+  }
+
+  private static Path createTempAgentJarFile(Path tempDir) {
+    URL url = OpenTelemetryAgent.class.getProtectionDomain().getCodeSource().getLocation();
+    try {
+      return copyTo(url, tempDir, "agent.jar");
+    } catch (IOException e) {
+      throw new IllegalStateException(
+          "Runtime attachment can't create agent jar file in temp directory", e);
+    }
+  }
+
+  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/src/main/java/io/opentelemetry/contrib/attach/RuntimeAttach.java

@@ -28,7 +28,7 @@ public final class RuntimeAttach {
       return;
     }
 
-    File javaagentFile = AgentFileLocator.locateAgentFile();
+    File javaagentFile = AgentFileProvider.getAgentFile();
     ByteBuddyAgent.attach(javaagentFile, getPid());
 
     if (!agentIsAttached()) {