add further emf + auto instrumentation unit tests and better java docs

Author: liustve

CHANGELOG.md

@@ -15,7 +15,7 @@ If your change does not need a CHANGELOG entry, add the "skip changelog" label t
 
 ### Enhancements
 
-- Add CloudWatch EMF metrics exporter for Java Agent and Lambda environment
+- Port CloudWatch EMF metrics exporter to Java 
   ([#1209](https://github.com/aws-observability/aws-otel-java-instrumentation/pull/1209))
 - Support X-Ray Trace Id extraction from Lambda Context object, and respect user-configured OTEL_PROPAGATORS in AWS Lamdba instrumentation
   ([#1191](https://github.com/aws-observability/aws-otel-java-instrumentation/pull/1191)) ([#1218](https://github.com/aws-observability/aws-otel-java-instrumentation/pull/1218))

awsagentprovider/src/main/java/software/amazon/opentelemetry/javaagent/providers/AwsApplicationSignalsConfigUtils.java

@@ -29,7 +29,9 @@ public final class AwsApplicationSignalsConfigUtils {
       Logger.getLogger(AwsApplicationSignalsCustomizerProvider.class.getName());
 
   /**
-   * Removes "awsemf" from OTEL_METRICS_EXPORTER if present.
+   * Removes "awsemf" from OTEL_METRICS_EXPORTER if present to prevent validation errors from OTel
+   * dependencies which would try to load metric exporters. We will contribute emf exporter to
+   * upstream for supporting OTel metrics in SDK
    *
    * @param configProps the configuration properties
    * @return Optional containing string with "awsemf" removed if the original OTEL_METRICS_EXPORTER

awsagentprovider/src/main/java/software/amazon/opentelemetry/javaagent/providers/AwsApplicationSignalsCustomizerProvider.java

@@ -88,8 +88,8 @@
 public final class AwsApplicationSignalsCustomizerProvider
     implements AutoConfigurationCustomizerProvider {
   // https://docs.aws.amazon.com/cli/v1/userguide/cli-configure-envvars.html
-  static final String AWS_REGION = "AWS_REGION";
-  static final String AWS_DEFAULT_REGION = "AWS_DEFAULT_REGION";
+  static final String AWS_REGION = "aws.region";
+  static final String AWS_DEFAULT_REGION = "aws.default.region";
   static final String AWS_LAMBDA_FUNCTION_NAME_CONFIG = "AWS_LAMBDA_FUNCTION_NAME";
   static final String LAMBDA_APPLICATION_SIGNALS_REMOTE_ENVIRONMENT =
       "LAMBDA_APPLICATION_SIGNALS_REMOTE_ENVIRONMENT";

awsagentprovider/src/main/java/software/amazon/opentelemetry/javaagent/providers/exporter/aws/common/BaseEmfExporter.java

@@ -40,11 +40,20 @@
 import java.util.logging.Logger;
 import software.amazon.opentelemetry.javaagent.providers.exporter.aws.common.emitter.LogEventEmitter;
 
+/**
+ * Base class for EMF metric exporters that converts OpenTelemetry metrics to CloudWatch EMF format.
+ */
 public abstract class BaseEmfExporter<T> implements MetricExporter {
   private static final Logger logger = Logger.getLogger(BaseEmfExporter.class.getName());
   private final String namespace;
   protected final LogEventEmitter<T> emitter;
 
+  /**
+   * Creates a new EMF exporter with the specified namespace and log emitter.
+   *
+   * @param namespace the CloudWatch metric namespace, defaults to "default" if null
+   * @param emitter the log event emitter for sending EMF logs
+   */
   protected BaseEmfExporter(String namespace, LogEventEmitter<T> emitter) {
     this.namespace = namespace != null ? namespace : "default";
     this.emitter = emitter;

awsagentprovider/src/main/java/software/amazon/opentelemetry/javaagent/providers/exporter/aws/common/LogEventEmitter.java

@@ -24,16 +24,16 @@
 import software.amazon.awssdk.retries.api.BackoffStrategy;
 import software.amazon.awssdk.services.cloudwatchlogs.CloudWatchLogsClient;
 import software.amazon.awssdk.services.cloudwatchlogs.model.*;
-import software.amazon.opentelemetry.javaagent.providers.exporter.aws.metrics.AwsCloudWatchEmfExporter;
 
 /**
- * CloudWatch Logs client for batching and sending log events.
+ * A log event emitter that sends Log Events to CloudWatch Logs.
  *
  * <p>This class handles the batching logic and CloudWatch Logs API interactions for sending EMF
  * logs while respecting CloudWatch Logs constraints.
  */
 public class CloudWatchLogsClientEmitter implements LogEventEmitter<CloudWatchLogsClient> {
-  private static final Logger logger = Logger.getLogger(AwsCloudWatchEmfExporter.class.getName());
+  private static final Logger logger =
+      Logger.getLogger(CloudWatchLogsClientEmitter.class.getName());
 
   // Constants for CloudWatch Logs limits
   // http://docs.aws.amazon.com/AmazonCloudWatch/latest/logs/cloudwatch_limits_cwl.html
@@ -344,8 +344,7 @@ private static StandardRetryStrategy createExponentialBackoffRetryStrategy() {
   /**
    * Container for a batch of CloudWatch log events with metadata.
    *
-   * <p>Tracks the log events, total byte size, and timestamps for efficient batching and
-   * validation.
+   * <p>Tracks the log events, total byte size, and timestamps for batching and validation.
    */
   private static class LogEventBatch {
     private final List<InputLogEvent> logEvents = new ArrayList<>();

awsagentprovider/src/main/java/software/amazon/opentelemetry/javaagent/providers/exporter/aws/common/emitter/CloudWatchLogsClientEmitter.java

@@ -20,6 +20,7 @@
 import java.util.logging.Level;
 import java.util.logging.Logger;
 
+/** A log event emitter that prints Log Events to Standard Out. */
 public class ConsoleEmitter implements LogEventEmitter<PrintStream> {
   private static final Logger logger = Logger.getLogger(ConsoleEmitter.class.getName());
   private final PrintStream emitter;

awsagentprovider/src/main/java/software/amazon/opentelemetry/javaagent/providers/exporter/aws/common/emitter/ConsoleEmitter.java

@@ -18,7 +18,7 @@
 import java.util.Map;
 
 /**
- * Generic interface for log emitters.
+ * Generic interface for log event emitters.
  *
  * @param <T> The type of the underlying emitter client
  */

awsagentprovider/src/main/java/software/amazon/opentelemetry/javaagent/providers/exporter/aws/common/emitter/LogEventEmitter.java

@@ -23,7 +23,7 @@
 import software.amazon.opentelemetry.javaagent.providers.exporter.aws.common.emitter.LogEventEmitter;
 
 /**
- * Metrics exporter for CloudWatch EMF format.
+ * EMF metrics exporter for sending data directly to CloudWatch Logs.
  *
  * <p>This exporter converts OTel metrics into CloudWatch EMF logs which are then sent to CloudWatch
  * Logs. CloudWatch Logs automatically extracts the metrics from the EMF logs.

awsagentprovider/src/main/java/software/amazon/opentelemetry/javaagent/providers/exporter/aws/metrics/AwsCloudWatchEmfExporter.java

@@ -23,6 +23,7 @@
 import software.amazon.opentelemetry.javaagent.providers.exporter.aws.common.emitter.ConsoleEmitter;
 import software.amazon.opentelemetry.javaagent.providers.exporter.aws.common.emitter.LogEventEmitter;
 
+/** EMF metrics exporter for printing data to Standard Out. */
 public class ConsoleEmfExporter extends BaseEmfExporter<PrintStream> {
   private static final Logger logger = Logger.getLogger(ConsoleEmfExporter.class.getName());
 
@@ -36,7 +37,7 @@ public ConsoleEmfExporter(String namespace) {
   }
 
   /**
-   * Initialize the Console EMF exporter with custom emitter for testing.
+   * Initialize the Console EMF exporter with custom emitter.
    *
    * @param namespace CloudWatch namespace for metrics
    * @param emitter Custom emitter