Add logging of the otel SDK configuration

custom/src/main/java/co/elastic/otel/ElasticAutoConfigurationCustomizerProvider.java

@@ -22,6 +22,7 @@
 import co.elastic.otel.dynamicconfig.BlockableMetricExporter;
 import co.elastic.otel.dynamicconfig.BlockableSpanExporter;
 import co.elastic.otel.dynamicconfig.CentralConfig;
+import co.elastic.otel.dynamicconfig.ConfigLogger;
 import co.elastic.otel.logging.AgentLog;
 import com.google.auto.service.AutoService;
 import io.opentelemetry.api.common.AttributeKey;
@@ -76,6 +77,7 @@ public void customize(AutoConfigurationCustomizer autoConfiguration) {
           AgentLog.addSpanLoggingIfRequired(providerBuilder, properties);
           return providerBuilder;
         });
+    ConfigLogger.triggerInitialLogConfig();
   }
 
   private void configureExporterUserAgentHeaders(AutoConfigurationCustomizer autoConfiguration) {

custom/src/main/java/co/elastic/otel/dynamicconfig/BlockableLogRecordExporter.java

@@ -74,4 +74,14 @@ public CompletableResultCode shutdown() {
   public void close() {
     delegate.close();
   }
+
+  @Override
+  public String toString() {
+    return "BlockableLogRecordExporter{"
+        + "sendingLogs="
+        + sendingLogs
+        + ", delegate="
+        + delegate
+        + '}';
+  }
 }

custom/src/main/java/co/elastic/otel/dynamicconfig/BlockableMetricExporter.java

@@ -87,4 +87,14 @@ public CompletableResultCode shutdown() {
   public void close() {
     delegate.close();
   }
+
+  @Override
+  public String toString() {
+    return "BlockableMetricExporter{"
+        + "sendingMetrics="
+        + sendingMetrics
+        + ", delegate="
+        + delegate
+        + '}';
+  }
 }

custom/src/main/java/co/elastic/otel/dynamicconfig/BlockableSpanExporter.java

@@ -69,4 +69,14 @@ public CompletableResultCode flush() {
   public CompletableResultCode shutdown() {
     return delegate.shutdown();
   }
+
+  @Override
+  public String toString() {
+    return "BlockableSpanExporter{"
+        + "sendingSpans="
+        + sendingSpans
+        + ", delegate="
+        + delegate
+        + '}';
+  }
 }

custom/src/main/java/co/elastic/otel/dynamicconfig/CentralConfig.java

@@ -70,6 +70,7 @@ public static void init(SdkTracerProviderBuilder providerBuilder, ConfigProperti
         configuration -> {
           logger.fine("Received configuration: " + configuration);
           Configs.applyConfigurations(configuration);
+          ConfigLogger.logConfig();
           return CentralConfigurationProcessor.Result.SUCCESS;
         });
 

custom/src/main/java/co/elastic/otel/dynamicconfig/ConfigLogger.java

@@ -0,0 +1,88 @@
+/*
+ * Licensed to Elasticsearch B.V. under one or more contributor
+ * license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright
+ * ownership. Elasticsearch B.V. licenses this file to you under
+ * the Apache License, Version 2.0 (the "License"); you may
+ * not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+package co.elastic.otel.dynamicconfig;
+
+import io.opentelemetry.api.GlobalOpenTelemetry;
+import io.opentelemetry.api.OpenTelemetry;
+import java.lang.reflect.Field;
+import java.util.logging.Logger;
+
+public class ConfigLogger {
+  private static final int DELAY_IN_SECONDS_AFTER_START_FOR_INITIAL_LOG;
+  private static final Logger logger = Logger.getLogger(ConfigLogger.class.getName());
+  private static volatile boolean firstLogged = false;
+
+  static {
+    String envDelay = System.getenv("ELASTIC_OTEL_JAVA_CONFIGURATION_LOG_DELAY_SECONDS");
+    String propDelay = System.getProperty("elastic.otel.java.configuration.log.delay.seconds");
+    int intDelay;
+    if (propDelay != null && propDelay.length() > 0) {
+      try {
+        intDelay = Integer.parseInt(propDelay);
+      } catch (Exception e) {
+        intDelay = 30;
+      }
+    } else if (envDelay != null && envDelay.length() > 0) {
+      try {
+        intDelay = Integer.parseInt(envDelay);
+      } catch (Exception e) {
+        intDelay = 30;
+      }
+    } else {
+      intDelay = 30;
+    }
+    DELAY_IN_SECONDS_AFTER_START_FOR_INITIAL_LOG = intDelay;
+  }
+
+  public static void logConfig() {
+    if (firstLogged) {
+      doLogConfig();
+    }
+  }
+
+  private static void doLogConfig() {
+    try {
+      logger.info("GlobalOpenTelemetry: " + getLogConfigString());
+    } catch (NoSuchFieldException | IllegalAccessException e) {
+      firstLogged = false; // resetting so we only log the error once
+      logger.warning(
+          "Error getting 'delegate' from " + GlobalOpenTelemetry.get() + ": " + e.getMessage());
+    }
+  }
+
+  static String getLogConfigString() throws NoSuchFieldException, IllegalAccessException {
+    OpenTelemetry obfuscatedConfig = GlobalOpenTelemetry.get();
+    Field config = obfuscatedConfig.getClass().getDeclaredField("delegate");
+    config.setAccessible(true);
+    return config.get(obfuscatedConfig).toString();
+  }
+
+  public static void triggerInitialLogConfig() {
+    new java.util.Timer()
+        .schedule(
+            new java.util.TimerTask() {
+              @Override
+              public void run() {
+                firstLogged = true;
+                doLogConfig();
+              }
+            },
+            1000 * DELAY_IN_SECONDS_AFTER_START_FOR_INITIAL_LOG);
+  }
+}

custom/src/main/java/co/elastic/otel/dynamicconfig/DynamicConfiguration.java

@@ -254,5 +254,10 @@ public TracerConfig apply(InstrumentationScopeInfo scopeInfo) {
     public void put(InstrumentationScopeInfo scope, TracerConfig tracerConfig) {
       map.put(scope.getName(), tracerConfig);
     }
+
+    @Override
+    public String toString() {
+      return "UpdatableConfigurator{" + "map=" + map + '}';
+    }
   }
 }

custom/src/test/java/co/elastic/otel/dynamicconfig/ConfigLoggerTest.java

@@ -0,0 +1,136 @@
+/*
+ * Licensed to Elasticsearch B.V. under one or more contributor
+ * license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright
+ * ownership. Elasticsearch B.V. licenses this file to you under
+ * the Apache License, Version 2.0 (the "License"); you may
+ * not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+package co.elastic.otel.dynamicconfig;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+import java.io.BufferedWriter;
+import java.io.File;
+import java.io.FileWriter;
+import java.io.IOException;
+import java.io.InputStream;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.concurrent.TimeUnit;
+import org.junit.jupiter.api.Test;
+
+public class ConfigLoggerTest {
+  static final String TARGET_CLASS_NAME = "TempTest321";
+
+  @Test
+  public void checkGlobalOpenTelemetryString() throws IOException {
+    String output = executeCommand(createTestTargetCommand(), 20);
+    assertThat(output).contains("ConfigLogger - GlobalOpenTelemetry");
+    assertThat(output).contains("tracerProvider=SdkTracerProvider");
+  }
+
+  static File createTestTarget() throws IOException {
+    String targetClass =
+        "public class "
+            + TARGET_CLASS_NAME
+            + " {\n"
+            + "  public static void main(String[] args) {\n"
+            + "    System.out.println(\"Test started\");\n"
+            + "    try {Thread.sleep(6_000L);} catch (InterruptedException e) {}\n"
+            + "    System.out.println(\"Test ended\");\n"
+            + "  }\n"
+            + "}\n";
+    File targetClassFile =
+        new File(System.getProperty("java.io.tmpdir"), TARGET_CLASS_NAME + ".java");
+    targetClassFile.deleteOnExit();
+    try (BufferedWriter writer = new BufferedWriter(new FileWriter(targetClassFile))) {
+      writer.write(targetClass);
+    }
+    return targetClassFile;
+  }
+
+  static String getAgentJarFile() {
+    // note File path with / is valid on Windows too
+    File[] jar =
+        new File("../agent/build/libs")
+            .listFiles(
+                (dir, name) ->
+                    name.matches("elastic-otel-javaagent-\\d\\.\\d\\.\\d-SNAPSHOT\\.jar"));
+    if (jar == null || jar.length != 1) {
+      throw new IllegalStateException(
+          "expecting exactly one agent jar file in ../agent/build/libs");
+    }
+    return jar[0].getAbsolutePath();
+  }
+
+  static List<String> createTestTargetCommand() throws IOException {
+    List<String> command = new ArrayList<>();
+    command.add("java");
+    command.add("-Xmx32m");
+    command.add("-javaagent:" + getAgentJarFile());
+    command.add("-Delastic.otel.java.configuration.log.delay.seconds=5");
+    command.add(createTestTarget().getAbsolutePath());
+    return command;
+  }
+
+  private static void pauseSeconds(int seconds) {
+    try {
+      Thread.sleep(seconds * 1_000L);
+    } catch (InterruptedException e) {
+    }
+  }
+
+  public static String executeCommand(List<String> command, int timeoutSeconds) throws IOException {
+    ProcessBuilder pb = new ProcessBuilder(command);
+    pb.redirectErrorStream(true);
+    Process childProcess = pb.start();
+
+    StringBuilder commandOutput = new StringBuilder();
+
+    boolean isAlive = true;
+    byte[] buffer = new byte[64 * 1000];
+    InputStream in = childProcess.getInputStream();
+    // stop trying if the time elapsed exceeds the timeout
+    while (isAlive && (timeoutSeconds > 0)) {
+      while (in.available() > 0) {
+        int lengthRead = in.read(buffer, 0, buffer.length);
+        commandOutput.append(new String(buffer, 0, lengthRead));
+      }
+      pauseSeconds(1);
+      timeoutSeconds--;
+      isAlive = childProcess.isAlive();
+    }
+    // it can die but still have output available buffered
+    while (in.available() > 0) {
+      int lengthRead = in.read(buffer, 0, buffer.length);
+      commandOutput.append(new String(buffer, 0, lengthRead));
+    }
+
+    // Cleanup as well as I can
+    boolean exited = false;
+    try {
+      exited = childProcess.waitFor(3, TimeUnit.SECONDS);
+    } catch (InterruptedException e) {
+    }
+    if (!exited) {
+      childProcess.destroy();
+      pauseSeconds(1);
+      if (childProcess.isAlive()) {
+        childProcess.destroyForcibly();
+      }
+    }
+
+    return commandOutput.toString();
+  }
+}

custom/src/test/java/co/elastic/otel/config/DynamicInstrumentationTest.java → custom/src/test/java/co/elastic/otel/dynamicconfig/DynamicInstrumentationTest.java

@@ -16,7 +16,7 @@
  * specific language governing permissions and limitations
  * under the License.
  */
-package co.elastic.otel.config;
+package co.elastic.otel.dynamicconfig;
 
 import static org.assertj.core.api.Assertions.assertThat;
 

internal-logging/src/main/java/co/elastic/otel/logging/AgentLog.java

@@ -185,5 +185,10 @@ public CompletableResultCode flush() {
     public CompletableResultCode shutdown() {
       return enabled.get() ? delegate.shutdown() : CompletableResultCode.ofSuccess();
     }
+
+    @Override
+    public String toString() {
+      return "DebugLogSpanExporter{" + "enabled=" + enabled + ", delegate=" + delegate + '}';
+    }
   }
 }