Provide access to VM arguments via shared CLIHelper (#8538)

* Abstract away getVMArgumentsThroughReflection into a VMArgsCache class

* Change underlying data structure of VMArgsCache to HashSet

* Update internal-api/src/main/java/datadog/trace/bootstrap/config/provider/VMArgsCache.java

Co-authored-by: datadog-datadog-prod-us1[bot] <88084959+datadog-datadog-prod-us1[bot]@users.noreply.github.com>

* Update internal-api/src/main/java/datadog/trace/bootstrap/config/provider/VMArgsCache.java

Co-authored-by: datadog-datadog-prod-us1[bot] <88084959+datadog-datadog-prod-us1[bot]@users.noreply.github.com>

* Update internal-api/src/main/java/datadog/trace/bootstrap/config/provider/VMArgsCache.java

Co-authored-by: datadog-datadog-prod-us1[bot] <88084959+datadog-datadog-prod-us1[bot]@users.noreply.github.com>

* Clean up for initial review

* move VMArgsCache to components/cli

* fix datadog.cli import

* nits: remove outdated comments

* annotate initJvmArgs with @SuppressForbidden to allow Class.forName() usage

* Fix package directory

* Cleanup code:
* store args in static field, make available via static getter
* use list of strings as storage type to begin with
* prefer NIO methods to read content (defaults to UTF8)
* use try-with-resources to ensure reader is closed
* check file exists as a quick short-circuit

* Remove warning when reflection fails

* Expose components:cli from internal-api

---------

Co-authored-by: datadog-datadog-prod-us1[bot] <88084959+datadog-datadog-prod-us1[bot]@users.noreply.github.com>
Co-authored-by: Stuart McCulloch <[email protected]>

Author: 3 people

Diff for: components/cli/build.gradle.kts

@@ -0,0 +1,9 @@
+plugins {
+  id("me.champeau.jmh")
+}
+
+apply(from = "$rootDir/gradle/java.gradle")
+
+jmh {
+  version = "1.28"
+}

Diff for: components/cli/src/main/java/datadog/cli/CLIHelper.java

@@ -0,0 +1,88 @@
+package datadog.cli;
+
+import de.thetaphi.forbiddenapis.SuppressForbidden;
+import java.io.BufferedReader;
+import java.lang.management.ManagementFactory;
+import java.lang.reflect.Field;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.nio.file.Paths;
+import java.util.Arrays;
+import java.util.Collections;
+import java.util.List;
+import java.util.Locale;
+
+public final class CLIHelper {
+  private static final List<String> VM_ARGS = findVmArgs();
+
+  public static List<String> getVmArgs() {
+    return VM_ARGS;
+  }
+
+  @SuppressForbidden
+  private static List<String> findVmArgs() {
+    // Try ProcFS on Linux
+    try {
+      if (isLinux()) {
+        Path cmdlinePath = Paths.get("/proc/self/cmdline");
+        if (Files.exists(cmdlinePath)) {
+          try (BufferedReader in = Files.newBufferedReader(cmdlinePath)) {
+            return Arrays.asList(in.readLine().split("\0"));
+          }
+        }
+      }
+    } catch (Throwable ignored) {
+      // Ignored exception
+    }
+
+    // Try Oracle-based
+    // IBM Semeru Runtime 1.8.0_345-b01 will throw UnsatisfiedLinkError here.
+    try {
+      final Class<?> managementFactoryHelperClass =
+          Class.forName("sun.management.ManagementFactoryHelper");
+
+      final Class<?> vmManagementClass = Class.forName("sun.management.VMManagement");
+
+      Object vmManagement;
+
+      try {
+        vmManagement =
+            managementFactoryHelperClass.getDeclaredMethod("getVMManagement").invoke(null);
+      } catch (final NoSuchMethodException e) {
+        // Older vm before getVMManagement() existed
+        final Field field = managementFactoryHelperClass.getDeclaredField("jvm");
+        field.setAccessible(true);
+        vmManagement = field.get(null);
+        field.setAccessible(false);
+      }
+
+      //noinspection unchecked
+      return (List<String>) vmManagementClass.getMethod("getVmArguments").invoke(vmManagement);
+    } catch (final ReflectiveOperationException | UnsatisfiedLinkError ignored) {
+      // Ignored exception
+    }
+
+    // Try IBM-based.
+    try {
+      final Class<?> VMClass = Class.forName("com.ibm.oti.vm.VM");
+      final String[] argArray = (String[]) VMClass.getMethod("getVMArgs").invoke(null);
+      return Arrays.asList(argArray);
+    } catch (final ReflectiveOperationException ignored) {
+      // Ignored exception
+    }
+
+    // Fallback to default
+    try {
+      return ManagementFactory.getRuntimeMXBean().getInputArguments();
+    } catch (final Throwable t) {
+      // Throws InvocationTargetException on modularized applications
+      // with non-opened java.management module
+      System.err.println("WARNING: Unable to get VM args using managed beans");
+    }
+    return Collections.emptyList();
+  }
+
+  private static boolean isLinux() {
+    return System.getProperty("os.name").toLowerCase(Locale.ROOT).contains("linux");
+  }
+}

Diff for: dd-java-agent/agent-bootstrap/src/main/java/datadog/trace/bootstrap/Constants.java

@@ -17,6 +17,7 @@ public final class Constants {
     "datadog.slf4j",
     "datadog.json",
     "datadog.context",
+    "datadog.cli",
     "datadog.appsec.api",
     "datadog.trace.api",
     "datadog.trace.bootstrap",

Diff for: dd-java-agent/build.gradle

@@ -203,6 +203,7 @@ tasks.withType(GenerateMavenPom).configureEach { task ->
 
 dependencies {
   implementation project(path: ':components:json')
+  implementation project(path: ':components:cli')
   modules {
     module("com.squareup.okio:okio") {
       replacedBy("com.datadoghq.okio:okio") // embed our patched fork

Diff for: dd-java-agent/src/main/java/datadog/trace/bootstrap/AgentBootstrap.java

@@ -2,22 +2,20 @@
 
 import static java.nio.charset.StandardCharsets.UTF_8;
 
+import datadog.cli.CLIHelper;
 import de.thetaphi.forbiddenapis.SuppressForbidden;
 import java.io.BufferedReader;
 import java.io.File;
 import java.io.IOException;
 import java.io.InputStreamReader;
 import java.io.PrintStream;
 import java.lang.instrument.Instrumentation;
-import java.lang.management.ManagementFactory;
-import java.lang.reflect.Field;
 import java.lang.reflect.Method;
 import java.net.URI;
 import java.net.URISyntaxException;
 import java.net.URL;
 import java.security.CodeSource;
 import java.util.ArrayList;
-import java.util.Arrays;
 import java.util.Collections;
 import java.util.IdentityHashMap;
 import java.util.List;
@@ -383,7 +381,7 @@ private static List<File> getAgentFilesFromVMArguments() {
       // - On IBM-based JDKs since at least 1.7
       // This prevents custom log managers from working correctly
       // Use reflection to bypass the loading of the class~
-      for (final String argument : getVMArgumentsThroughReflection()) {
+      for (final String argument : CLIHelper.getVmArgs()) {
         if (argument.startsWith(JAVA_AGENT_ARGUMENT)) {
           int index = argument.indexOf('=', JAVA_AGENT_ARGUMENT.length());
           String agentPathname =
@@ -424,57 +422,6 @@ private static File getAgentFileUsingClassLoaderLookup() throws URISyntaxExcepti
     return javaagentFile;
   }
 
-  @SuppressForbidden
-  private static List<String> getVMArgumentsThroughReflection() {
-    // Try Oracle-based
-    // IBM Semeru Runtime 1.8.0_345-b01 will throw UnsatisfiedLinkError here.
-    try {
-      final Class<?> managementFactoryHelperClass =
-          Class.forName("sun.management.ManagementFactoryHelper");
-
-      final Class<?> vmManagementClass = Class.forName("sun.management.VMManagement");
-
-      Object vmManagement;
-
-      try {
-        vmManagement =
-            managementFactoryHelperClass.getDeclaredMethod("getVMManagement").invoke(null);
-      } catch (final NoSuchMethodException e) {
-        // Older vm before getVMManagement() existed
-        final Field field = managementFactoryHelperClass.getDeclaredField("jvm");
-        field.setAccessible(true);
-        vmManagement = field.get(null);
-        field.setAccessible(false);
-      }
-
-      //noinspection unchecked
-      return (List<String>) vmManagementClass.getMethod("getVmArguments").invoke(vmManagement);
-    } catch (final ReflectiveOperationException | UnsatisfiedLinkError ignored) {
-      // Ignored exception
-    }
-
-    // Try IBM-based.
-    try {
-      final Class<?> VMClass = Class.forName("com.ibm.oti.vm.VM");
-      final String[] argArray = (String[]) VMClass.getMethod("getVMArgs").invoke(null);
-      return Arrays.asList(argArray);
-    } catch (final ReflectiveOperationException ignored) {
-      // Ignored exception
-    }
-
-    // Fallback to default
-    try {
-      System.err.println(
-          "WARNING: Unable to get VM args through reflection. A custom java.util.logging.LogManager may not work correctly");
-      return ManagementFactory.getRuntimeMXBean().getInputArguments();
-    } catch (final Throwable t) {
-      // Throws InvocationTargetException on modularized applications
-      // with non-opened java.management module
-      System.err.println("WARNING: Unable to get VM args using managed beans");
-    }
-    return Collections.emptyList();
-  }
-
   private static void checkJarManifestMainClassIsThis(final URL jarUrl) throws IOException {
     final URL manifestUrl = new URL("jar:" + jarUrl + "!/META-INF/MANIFEST.MF");
     final String mainClassLine = "Main-Class: " + thisClass.getCanonicalName();

Diff for: dd-java-agent/testing/src/main/groovy/datadog/trace/agent/test/SpockRunner.java

@@ -40,6 +40,7 @@ public class SpockRunner extends JUnitPlatform {
     "datadog.slf4j",
     "datadog.json",
     "datadog.context",
+    "datadog.cli",
     "datadog.appsec.api",
     "datadog.trace.api",
     "datadog.trace.bootstrap",

Diff for: gradle/dependencies.gradle

@@ -18,6 +18,7 @@ final class CachedData {
       exclude(project(':communication'))
       exclude(project(':components:context'))
       exclude(project(':components:json'))
+      exclude(project(':components:cli'))
       exclude(project(':remote-config:remote-config-api'))
       exclude(project(':remote-config:remote-config-core'))
       exclude(project(':telemetry'))

Diff for: internal-api/build.gradle

@@ -234,6 +234,7 @@ dependencies {
   api project(':dd-trace-api')
   api libs.slf4j
   api project(':components:context')
+  api project(':components:cli')
   api project(":utils:time-utils")
 
   // has to be loaded by system classloader:

Diff for: settings.gradle

@@ -66,6 +66,7 @@ include ':dd-java-agent:agent-otel:otel-shim'
 include ':dd-java-agent:agent-otel:otel-tooling'
 
 include ':communication'
+include ':components:cli'
 include ':components:context'
 include ':components:json'
 include ':telemetry'