Add profiler env check command to AgentCLI (#8671)

DataDog · ValentinZakharov · May 13, 2025 · Mar 28, 2025 · Mar 28, 2025 · Mar 30, 2025
commit 091ee8019383de0e9739cddc364b35016a87d85f
diff --git a/...-crashtracking/src/main/java/com/datadog/crashtracking/OOMENotifierScriptInitializer.java b/...-crashtracking/src/main/java/com/datadog/crashtracking/OOMENotifierScriptInitializer.java
@@ -43,7 +43,7 @@ static void initialize(String onOutOfMemoryVal) {
     Path scriptPath = getOOMEScripPath(onOutOfMemoryVal);
     if (scriptPath == null) {
       LOG.debug(
-          "OOME notifier script value ({}) does not follow the expected format: <path>/dd_ome_notifier.(sh|bat) %p. OOME tracking is disabled.",
+          "OOME notifier script value ({}) does not follow the expected format: <path>/dd_oome_notifier.(sh|bat) %p. OOME tracking is disabled.",
           onOutOfMemoryVal);
       return;
     }

diff --git a/dd-java-agent/agent-tooling/src/main/java/datadog/trace/agent/tooling/AgentCLI.java b/dd-java-agent/agent-tooling/src/main/java/datadog/trace/agent/tooling/AgentCLI.java
@@ -4,6 +4,7 @@
 import com.datadog.crashtracking.OOMENotifier;
 import datadog.trace.agent.tooling.bytebuddy.SharedTypePools;
 import datadog.trace.agent.tooling.bytebuddy.matcher.HierarchyMatchers;
+import datadog.trace.agent.tooling.profiler.EnvironmentChecker;
 import datadog.trace.bootstrap.Agent;
 import datadog.trace.bootstrap.InitializationTelemetry;
 import datadog.trace.bootstrap.instrumentation.api.AgentSpan;
@@ -126,6 +127,12 @@ public static void scanDependencies(final String[] args) throws Exception {
     System.out.println("Scan finished");
   }
 
+  public static void checkProfilerEnv(String temp) {
+    if (!EnvironmentChecker.checkEnvironment(temp)) {
+      System.exit(1);
+    }
+  }
+
   private static void recursiveDependencySearch(Consumer<File> invoker, File origin)
       throws IOException {
     invoker.accept(origin);

diff --git a/.../agent-tooling/src/main/java/datadog/trace/agent/tooling/profiler/EnvironmentChecker.java b/.../agent-tooling/src/main/java/datadog/trace/agent/tooling/profiler/EnvironmentChecker.java
@@ -0,0 +1,229 @@
+package datadog.trace.agent.tooling.profiler;
+
+import datadog.trace.api.Platform;
+import java.io.File;
+import java.io.IOException;
+import java.net.URL;
+import java.nio.file.FileSystems;
+import java.nio.file.FileVisitResult;
+import java.nio.file.FileVisitor;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.nio.file.Paths;
+import java.nio.file.attribute.BasicFileAttributes;
+import java.nio.file.attribute.PosixFilePermissions;
+import java.util.Set;
+import java.util.jar.JarFile;
+
+public final class EnvironmentChecker {
+  public static boolean checkEnvironment(String temp) {
+    if (!Platform.isJavaVersionAtLeast(8)) {
+      System.out.println("Profiler requires Java 8 or newer");
+      return false;
+    }
+    System.out.println(
+        "Using Java version: "
+            + Platform.getRuntimeVersion()
+            + " ("
+            + System.getProperty("java.home")
+            + ")");
+    System.out.println("Running as user: " + System.getProperty("user.name"));
+    boolean result = false;
+    result |= checkJFR();
+    result |= checkDdprof();
+    if (!result) {;
+      System.out.println("Profiler is not supported on this JVM.");
+      return false;
+    } else {
+      System.out.println("Profiler is supported on this JVM.");
+    }
+    System.out.println();
+    if (!checkTempLocation(temp)) {
+      System.out.println(
+          "Profiler will not work properly due to issues with temp directory location.");
+      return false;
+    } else {
+      if (!temp.equals(System.getProperty("java.io.tmpdir"))) {
+        System.out.println(
+            "! Make sure to add '-Ddd.profiling.tempdir=" + temp + "' to your JVM command line !");
+      }
+    }
+    System.out.println("Profiler is ready to be used.");
+    return true;
+  }
+
+  private static boolean checkJFR() {
+    if (Platform.isOracleJDK8()) {
+      System.out.println(
+          "JFR is commercial feature in Oracle JDK 8. Make sure you have the right license.");
+      return true;
+    } else if (Platform.isJ9()) {
+      System.out.println("JFR is not supported on J9 JVM.");
+      return false;
+    } else {
+      System.out.println("JFR is supported on " + Platform.getRuntimeVersion());
+      return true;
+    }
+  }
+
+  private static boolean checkDdprof() {
+    if (!Platform.isLinux()) {
+      System.out.println("Datadog profiler is only supported on Linux.");
+      return false;
+    } else {
+      System.out.println("Datadog profiler is supported on " + Platform.getRuntimeVersion());
+      return true;
+    }
+  }
+
+  private static boolean checkTempLocation(String temp) {
+    // Check if the temp directory is writable
+    if (temp == null || temp.isEmpty()) {
+      System.out.println("Temp directory is not specified.");
+      return false;
+    }
+
+    System.out.println("Checking temporary directory: " + temp);
+
+    Path base = Paths.get(temp);
+    if (!Files.exists(base)) {
+      System.out.println("Temporary directory does not exist: " + base);
+      return false;
+    }
+    Path target = base.resolve("dd-profiler").normalize();
+    boolean rslt = true;
+    Set<String> supportedViews = FileSystems.getDefault().supportedFileAttributeViews();
+    boolean isPosix = supportedViews.contains("posix");
+    try {
+      if (isPosix) {
+        Files.createDirectories(
+            target,
+            PosixFilePermissions.asFileAttribute(PosixFilePermissions.fromString("rwx------")));
+      } else {
+        // non-posix, eg. Windows - let's rely on the created folders being world-writable
+        Files.createDirectories(target);
+      }
+      System.out.println("Temporary directory is writable: " + target);
+      rslt &= checkCreateTempFile(target);
+      rslt &= checkLoadLibrary(target);
+    } catch (Exception e) {
+      System.out.println("Unable to create temp directory in location " + temp);
+      if (isPosix) {
+        try {
+          System.out.println(
+              "Base dir: "
+                  + base
+                  + " ["
+                  + PosixFilePermissions.toString(Files.getPosixFilePermissions(base))
+                  + "]");
+        } catch (IOException ignored) {
+          // never happens
+        }
+      }
+      System.out.println("Error: " + e);
+    } finally {
+      if (Files.exists(target)) {
+        try {
+          Files.walkFileTree(
+              target,
+              new FileVisitor<Path>() {
+                @Override
+                public FileVisitResult preVisitDirectory(Path dir, BasicFileAttributes attrs)
+                    throws IOException {
+                  return FileVisitResult.CONTINUE;
+                }
+
+                @Override
+                public FileVisitResult visitFile(Path file, BasicFileAttributes attrs)
+                    throws IOException {
+                  Files.delete(file);
+                  return FileVisitResult.CONTINUE;
+                }
+
+                @Override
+                public FileVisitResult visitFileFailed(Path file, IOException exc)
+                    throws IOException {
+                  return FileVisitResult.CONTINUE;
+                }
+
+                @Override
+                public FileVisitResult postVisitDirectory(Path dir, IOException exc)
+                    throws IOException {
+                  Files.delete(dir);
+                  return FileVisitResult.CONTINUE;
+                }
+              });
+        } catch (IOException ignored) {
+          // should never happen
+        }
+      }
+    }
+    return rslt;
+  }
+
+  private static boolean checkCreateTempFile(Path target) {
+    // create a file to check if the directory is writable
+    try {
+      System.out.println("Attempting to create a test file in: " + target);
+      Path testFile = target.resolve("testfile");
+      Files.createFile(testFile);
+      System.out.println("Test file created: " + testFile);
+      return true;
+    } catch (Exception e) {
+      System.out.println("Unable to create test file in temp directory " + target);
+      System.out.println("Error: " + e);
+    }
+    return false;
+  }
+
+  private static boolean checkLoadLibrary(Path target) {
+    if (!Platform.isLinux()) {
+      // we are loading the native library only on linux
+      System.out.println("Skipping native library check on non-linux platform");
+      return true;
+    }
+    boolean rslt = true;
+    try {
+      rslt &= extractSoFromJar(target);
+      if (rslt) {
+        Path libFile = target.resolve("libjavaProfiler.so");
+        System.out.println("Attempting to load native library from: " + libFile);
+        System.load(libFile.toString());
+        System.out.println("Native library loaded successfully");
+      }
+      return true;
+    } catch (Throwable t) {
+      System.out.println("Unable to load native library in temp directory " + target);
+      System.out.println("Error: " + t);
+
A93C
      return false;
+    }
+  }
+
+  private static boolean extractSoFromJar(Path target) throws Exception {
+    URL jarUrl = EnvironmentChecker.class.getProtectionDomain().getCodeSource().getLocation();
+    try (JarFile jarFile = new JarFile(new File(jarUrl.toURI()))) {
+      return jarFile.stream()
+          .filter(e -> e.getName().contains("libjavaProfiler.so"))
+          .filter(
+              e ->
+                  e.getName().contains(Platform.isAarch64() ? "/linux-arm64/" : "/linux-x64/")
+                      && (!Platform.isMusl() || e.getName().contains("-musl")))
+          .findFirst()
+          .map(
+              e -> {
+                try {
+                  Path soFile = target.resolve("libjavaProfiler.so");
+                  Files.createDirectories(soFile.getParent());
+                  Files.copy(jarFile.getInputStream(e), soFile);
+                  System.out.println("Native library extracted to: " + soFile);
+                  return true;
+                } catch (Throwable t) {
+                  System.out.println("Failed to extract or load native library");
+                  System.out.println("Error: " + t);
+                }
+                return false;
+              })
+          .orElse(Boolean.FALSE);
+    }
+  }
+}
diff --git a/dd-java-agent/src/main/java/datadog/trace/bootstrap/AgentJar.java b/dd-java-agent/src/main/java/datadog/trace/bootstrap/AgentJar.java
@@ -33,6 +33,9 @@ public static void main(final String[] args) {
           case "scanDependencies":
             scanDependencies(args);
             break;
+          case "checkProfilerEnv":
+            checkProfilerEnv(args);
+            break;
           case "--list-integrations":
           case "-li":
             printIntegrationNames();
@@ -63,6 +66,7 @@ private static void printUsage() {
     System.out.println("  sampleTrace [-c count] [-i interval]");
     System.out.println("  uploadCrash file ...");
     System.out.println("  scanDependencies <path> ...");
+    System.out.println("  checkProfilerEnv [temp]");
     System.out.println("  [-li | --list-integrations]");
     System.out.println("  [-h  | --help]");
     System.out.println("  [-v  | --version]");
@@ -164,4 +168,10 @@ public static String getAgentVersion() throws IOException {
 
     return sb.toString().trim();
   }
+
+  private static void checkProfilerEnv(final String[] args) throws Exception {
+    String tmpDir = args.length == 2 ? args[1] : System.getProperty("java.io.tmpdir");
+
+    installAgentCLI().getMethod("checkProfilerEnv", String.class).invoke(null, tmpDir);
+  }
 }
diff --git a/internal-api/src/main/java/datadog/trace/api/Platform.java b/internal-api/src/main/java/datadog/trace/api/Platform.java
@@ -1,6 +1,14 @@
 package datadog.trace.api;
 
+import java.io.BufferedReader;
+import java.io.FileReader;
+import java.io.IOException;
+import java.io.InputStream;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.nio.file.Paths;
 import java.util.ArrayList;
+import java.util.Arrays;
 import java.util.List;
 import java.util.Locale;
 
@@ -276,6 +284,94 @@ public static boolean isMac() {
     return os.contains("mac");
   }
 
+  public static boolean isAarch64() {
+    return System.getProperty("os.arch").toLowerCase().contains("aarch64");
+  }
+
+  public static boolean isMusl() {
+    if (!isLinux()) {
+      return false;
+    }
+    // check the Java exe then fall back to proc/self maps
+    try {
+      return isMuslJavaExecutable();
+    } catch (IOException e) {
+      try {
+        return isMuslProcSelfMaps();
+      } catch (IOException ignore) {
+        return false;
+      }
+    }
+  }
+
+  static boolean isMuslProcSelfMaps() throws IOException {
+    try (BufferedReader reader = new BufferedReader(new FileReader("/proc/self/maps"))) {
+      String line;
+      while ((line = reader.readLine()) != null) {
+        if (line.contains("-musl-")) {
+          return true;
+        }
+        if (line.contains("/libc.")) {
+          return false;
+        }
+      }
+    }
+    return false;
+  }
+
+  /**
+   * There is information about the linking in the ELF file. Since properly parsing ELF is not
   * trivial this code will attempt a brute-force approach and will scan the first 4096 bytes of the
+   * 'java' program image for anything prefixed with `/ld-` - in practice this will contain
+   * `/ld-musl` for musl systems and probably something else for non-musl systems (eg.
+   * `/ld-linux-...`). However, if such string is missing should indicate that the system is not a
+   * musl one.
+   */
+  static boolean isMuslJavaExecutable() throws IOException {
+
+    byte[] magic = new byte[] {(byte) 0x7f, (byte) 'E', (byte) 'L', (byte) 'F'};
+    byte[] prefix = new byte[] {(byte) '/', (byte) 'l', (byte) 'd', (byte) '-'}; // '/ld-*'
+    byte[] musl = new byte[] {(byte) 'm', (byte) 'u', (byte) 's', (byte) 'l'}; // 'musl'
+
+    Path binary = Paths.get(System.getProperty("java.home"), "bin", "java");
+    byte[] buffer = new byte[4096];
+
+    try (InputStream is = Files.newInputStream(binary)) {
+      int read = is.read(buffer, 0, 4);
+      if (read != 4 || !containsArray(buffer, 0, magic)) {
+        throw new IOException(Arrays.toString(buffer));
+      }
+      read = is.read(buffer);
+      if (read <= 0) {
+        throw new IOException();
+      }
+      int prefixPos = 0;
+      for (int i = 0; i < read; i++) {
+        if (buffer[i] == prefix[prefixPos]) {
+          if (++prefixPos == prefix.length) {
+            return containsArray(buffer, i + 1, musl);
+          }
+        } else {
+          prefixPos = 0;
+        }
+      }
+    }
+    return false;
+  }
+
+  private static boolean containsArray(byte[] container, int offset, byte[] contained) {
+    for (int i = 0; i < contained.length; i++) {
+      int leftPos = offset + i;
+      if (leftPos >= container.length) {
+        return false;
+      }
+      if (container[leftPos] != contained[i]) {
+        return false;
+      }
+    }
+    return true;
+  }
+
   public static boolean isOracleJDK8() {
     return isJavaVersion(8)
         && RUNTIME.vendor.contains("Oracle")