use json format for spans for elastic logging option

Author: SylvainJuge

internal-logging/build.gradle.kts

@@ -12,6 +12,7 @@ dependencies {
   compileOnly("io.opentelemetry.javaagent:opentelemetry-javaagent-bootstrap")
   compileOnly("io.opentelemetry:opentelemetry-sdk-extension-autoconfigure-spi")
   compileOnly("io.opentelemetry:opentelemetry-exporter-logging")
+  compileOnly("io.opentelemetry:opentelemetry-exporter-logging-otlp")
   compileOnly(libs.slf4j.api)
   implementation(libs.bundles.log4j2) {
     // Workaround for https://github.com/apache/logging-log4j2/issues/3754

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

@@ -21,6 +21,7 @@
 import static java.util.Collections.emptyList;
 
 import io.opentelemetry.exporter.logging.LoggingSpanExporter;
+import io.opentelemetry.exporter.logging.otlp.OtlpJsonLoggingSpanExporter;
 import io.opentelemetry.sdk.autoconfigure.spi.ConfigProperties;
 import io.opentelemetry.sdk.common.CompletableResultCode;
 import io.opentelemetry.sdk.trace.SdkTracerProviderBuilder;
@@ -45,16 +46,32 @@ public class AgentLog {
   /** root logger is an empty string */
   private static final String ROOT_LOGGER_NAME = "";
 
+  private static boolean logPlainText = false;
+
   /**
    * debug span logging exporter that can be controlled at runtime, only used when logging span
    * exporter has not been explicitly configured.
    */
-  private static final DebugLogSpanExporter debugLogSpanExporter =
-      new DebugLogSpanExporter(LoggingSpanExporter.create());
+  private static DebugLogSpanExporter debugLogSpanExporter = null;
 
   private AgentLog() {}
 
-  public static void init() {
+  /**
+   * Initializes agent logging
+   *
+   * @param usePlainTextLog {@literal true} to use plain text logging, `{@literal false} to use JSON
+   * @param initialLevel initial log level to configure
+   */
+  public static void init(boolean usePlainTextLog, Level initialLevel) {
+    internalInit();
+    setLevel(initialLevel);
+    logPlainText = usePlainTextLog;
+    debugLogSpanExporter =
+        new DebugLogSpanExporter(
+            logPlainText ? LoggingSpanExporter.create() : OtlpJsonLoggingSpanExporter.create());
+  }
+
+  private static void internalInit() {
 
     ConfigurationBuilder<BuiltConfiguration> conf =
         ConfigurationBuilderFactory.newConfigurationBuilder();
@@ -74,8 +91,11 @@ public static void addSpanLoggingIfRequired(
     // Replicate behavior of the upstream agent: span logging exporter is automatically added when
     // not already present when debugging. When logging exporter has been explicitly configured,
     // spans logging will be done by the explicitly configured logging exporter instance.
+
+    String exporterName = logPlainText ? "logging" : "otlp-logging";
+
     boolean loggingExporterNotAlreadyConfigured =
-        !config.getList("otel.traces.exporter", emptyList()).contains("logging");
+        !config.getList("otel.traces.exporter", emptyList()).contains(exporterName);
     if (loggingExporterNotAlreadyConfigured) {
       providerBuilder.addSpanProcessor(SimpleSpanProcessor.create(debugLogSpanExporter));
     }
@@ -114,7 +134,7 @@ public static void setLevel(String level) {
    *
    * @param level log level
    */
-  public static void setLevel(Level level) {
+  public static synchronized void setLevel(Level level) {
     // Using log4j2 implementation allows to change the log level programmatically at runtime
     // which is not directly possible through the slf4j API and simple implementation used in
     // upstream distribution.

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

@@ -22,6 +22,7 @@
 import io.opentelemetry.javaagent.bootstrap.InternalLogger;
 import io.opentelemetry.javaagent.tooling.LoggingCustomizer;
 import io.opentelemetry.javaagent.tooling.config.EarlyInitAgentConfig;
+import java.util.Optional;
 import org.apache.logging.log4j.Level;
 import org.slf4j.LoggerFactory;
 
@@ -43,20 +44,19 @@ public void init(EarlyInitAgentConfig earlyConfig) {
     // make the agent internal logger delegate to slf4j, which will delegate to log4j
     InternalLogger.initialize(Slf4jInternalLogger::create);
 
-    AgentLog.init();
-
-    Level level = null;
-    if (earlyConfig.getBoolean(AgentLog.OTEL_JAVAAGENT_DEBUG, false)) {
+    boolean upstreamDebugEnabled = earlyConfig.getBoolean(AgentLog.OTEL_JAVAAGENT_DEBUG, false);
+    Level level;
+    if (upstreamDebugEnabled) {
       // set debug logging when enabled through configuration to behave like the upstream
       // distribution
       level = Level.DEBUG;
     } else {
-      String levelConfig = earlyConfig.getString("elastic.otel.javaagent.log.level");
-      if (levelConfig != null) {
-        level = Level.getLevel(levelConfig);
-      }
+      level =
+          Optional.ofNullable(earlyConfig.getString("elastic.otel.javaagent.log.level"))
+              .map(Level::getLevel)
+              .orElse(Level.INFO);
     }
-    AgentLog.setLevel(level != null ? level : Level.INFO);
+    AgentLog.init(upstreamDebugEnabled, level);
   }
 
   @Override