Improve detection of resource attributes on ECS

sdk-extensions/aws/src/main/java/io/opentelemetry/sdk/extension/aws/resource/EcsResource.java

@@ -5,23 +5,30 @@
 
 package io.opentelemetry.sdk.extension.aws.resource;
 
+import com.fasterxml.jackson.core.JsonFactory;
+import com.fasterxml.jackson.core.JsonParser;
+import com.fasterxml.jackson.core.JsonToken;
 import io.opentelemetry.api.common.Attributes;
 import io.opentelemetry.api.common.AttributesBuilder;
 import io.opentelemetry.sdk.resources.Resource;
 import io.opentelemetry.semconv.resource.attributes.ResourceAttributes;
-import java.net.InetAddress;
-import java.net.UnknownHostException;
+import java.io.IOException;
+import java.util.Collections;
 import java.util.Map;
+import java.util.Optional;
 import java.util.logging.Level;
 import java.util.logging.Logger;
+import java.util.regex.Matcher;
+import java.util.regex.Pattern;
+import javax.annotation.Nullable;
 
 /**
  * A factory for a {@link Resource} which provides information about the current ECS container if
  * running on AWS ECS.
  */
 public final class EcsResource {
   private static final Logger logger = Logger.getLogger(EcsResource.class.getName());
-
+  private static final JsonFactory JSON_FACTORY = new JsonFactory();
   private static final String ECS_METADATA_KEY_V4 = "ECS_CONTAINER_METADATA_URI_V4";
   private static final String ECS_METADATA_KEY_V3 = "ECS_CONTAINER_METADATA_URI";
 
@@ -36,38 +43,224 @@ public static Resource get() {
   }
 
   private static Resource buildResource() {
-    return buildResource(System.getenv(), new DockerHelper());
+    return buildResource(System.getenv(), new SimpleHttpClient());
   }
 
   // Visible for testing
-  static Resource buildResource(Map<String, String> sysEnv, DockerHelper dockerHelper) {
-    if (!isOnEcs(sysEnv)) {
-      return Resource.empty();
+  static Resource buildResource(Map<String, String> sysEnv, SimpleHttpClient httpClient) {
+    // Note: If V4 is set V3 is set as well, so check V4 first.
+    String ecsMetadataUrl =
+        sysEnv.getOrDefault(ECS_METADATA_KEY_V4, sysEnv.getOrDefault(ECS_METADATA_KEY_V3, ""));
+    if (!ecsMetadataUrl.isEmpty()) {
+      AttributesBuilder attrBuilders = Attributes.builder();
+      fetchMetadata(httpClient, ecsMetadataUrl, attrBuilders);
+      // For TaskARN, Family, Revision.
+      // May put the same attribute twice but that shouldn't matter.
+      fetchMetadata(httpClient, ecsMetadataUrl + "/task", attrBuilders);
+      return Resource.create(attrBuilders.build(), ResourceAttributes.SCHEMA_URL);
     }
+    // Not running on ECS
+    return Resource.empty();
+  }
 
-    AttributesBuilder attrBuilders = Attributes.builder();
+  static void fetchMetadata(
+      SimpleHttpClient httpClient, String url, AttributesBuilder attrBuilders) {
+    String json = httpClient.fetchString("GET", url, Collections.emptyMap(), null);
+    if (json.isEmpty()) {
+      return;
+    }
     attrBuilders.put(ResourceAttributes.CLOUD_PROVIDER, ResourceAttributes.CloudProviderValues.AWS);
     attrBuilders.put(
         ResourceAttributes.CLOUD_PLATFORM, ResourceAttributes.CloudPlatformValues.AWS_ECS);
-    try {
-      String hostName = InetAddress.getLocalHost().getHostName();
-      attrBuilders.put(ResourceAttributes.CONTAINER_NAME, hostName);
-    } catch (UnknownHostException e) {
-      logger.log(Level.WARNING, "Could not get docker container name from hostname.", e);
+    try (JsonParser parser = JSON_FACTORY.createParser(json)) {
+      parser.nextToken();
+      LogArnBuilder logArnBuilder = new LogArnBuilder();
+      parseResponse(parser, attrBuilders, logArnBuilder);
+
+      logArnBuilder
+          .getLogGroupArn()
+          .ifPresent(
+              logGroupArn -> {
+                attrBuilders.put(
+                    ResourceAttributes.AWS_LOG_GROUP_ARNS, Collections.singletonList(logGroupArn));
+              });
+
+      logArnBuilder
+          .getLogStreamArn()
+          .ifPresent(
+              logStreamArn -> {
+                attrBuilders.put(
+                    ResourceAttributes.AWS_LOG_STREAM_ARNS,
+                    Collections.singletonList(logStreamArn));
+              });
+    } catch (IOException e) {
+      logger.log(Level.WARNING, "Can't get ECS metadata", e);
     }
+  }
 
-    String containerId = dockerHelper.getContainerId();
-    if (containerId != null && !containerId.isEmpty()) {
-      attrBuilders.put(ResourceAttributes.CONTAINER_ID, containerId);
+  static void parseResponse(
+      JsonParser parser, AttributesBuilder attrBuilders, LogArnBuilder logArnBuilder)
+      throws IOException {
+    if (!parser.isExpectedStartObjectToken()) {
+      logger.log(Level.WARNING, "Couldn't parse ECS metadata, invalid JSON");
+      return;
     }
 
-    return Resource.create(attrBuilders.build(), ResourceAttributes.SCHEMA_URL);
+    while (parser.nextToken() != JsonToken.END_OBJECT) {
+      String value = parser.nextTextValue();
+      switch (parser.getCurrentName()) {
+        case "DockerId":
+          attrBuilders.put(ResourceAttributes.CONTAINER_ID, value);
+          break;
+        case "DockerName":
+          attrBuilders.put(ResourceAttributes.CONTAINER_NAME, value);
+          break;
+        case "ContainerARN":
+          attrBuilders.put(ResourceAttributes.AWS_ECS_CONTAINER_ARN, value);
+          logArnBuilder.setContainerArn(value);
+          break;
+        case "Image":
+          DockerImage parsedImage = DockerImage.parse(value);
+          if (parsedImage != null) {
+            attrBuilders.put(ResourceAttributes.CONTAINER_IMAGE_NAME, parsedImage.getRepository());
+            attrBuilders.put(ResourceAttributes.CONTAINER_IMAGE_TAG, parsedImage.getTag());
+          }
+          break;
+        case "ImageID":
+          attrBuilders.put("aws.ecs.container.image.id", value);
+          break;
+        case "LogOptions":
+          // Recursively parse LogOptions
+          parseResponse(parser, attrBuilders, logArnBuilder);
+          break;
+        case "awslogs-group":
+          attrBuilders.put(ResourceAttributes.AWS_LOG_GROUP_NAMES, value);
+          logArnBuilder.setLogGroupName(value);
+          break;
+        case "awslogs-stream":
+          attrBuilders.put(ResourceAttributes.AWS_LOG_STREAM_NAMES, value);
+          logArnBuilder.setLogStreamName(value);
+          break;
+        case "awslogs-region":
+          logArnBuilder.setRegion(value);
+          break;
+        case "TaskARN":
+          attrBuilders.put(ResourceAttributes.AWS_ECS_TASK_ARN, value);
+          break;
+        case "LaunchType":
+          attrBuilders.put(ResourceAttributes.AWS_ECS_LAUNCHTYPE, value.toLowerCase());
+          break;
+        case "Family":
+          attrBuilders.put(ResourceAttributes.AWS_ECS_TASK_FAMILY, value);
+          break;
+        case "Revision":
+          attrBuilders.put(ResourceAttributes.AWS_ECS_TASK_REVISION, value);
+          break;
+        default:
+          parser.skipChildren();
+          break;
+      }
+    }
   }
 
-  private static boolean isOnEcs(Map<String, String> sysEnv) {
-    return !sysEnv.getOrDefault(ECS_METADATA_KEY_V3, "").isEmpty()
-        || !sysEnv.getOrDefault(ECS_METADATA_KEY_V4, "").isEmpty();
+  private EcsResource() {}
+
+  /**
+   * This builder can piece together the ARN of a log group or a log stream from region, account,
+   * group name and stream name as the ARN isn't part of the ECS metadata.
+   *
+   * <p>If we just set AWS_LOG_GROUP_NAMES then the CloudWatch X-Ray traces view displays "An error
+   * occurred fetching your data". That's why it's important we set the ARN.
+   */
+  private static class LogArnBuilder {
+
+    @Nullable String region;
+    @Nullable String account;
+    @Nullable String logGroupName;
+    @Nullable String logStreamName;
+
+    void setRegion(@Nullable String region) {
+      this.region = region;
+    }
+
+    void setLogGroupName(@Nullable String logGroupName) {
+      this.logGroupName = logGroupName;
+    }
+
+    void setLogStreamName(@Nullable String logStreamName) {
+      this.logStreamName = logStreamName;
+    }
+
+    void setContainerArn(@Nullable String containerArn) {
+      if (containerArn != null) {
+        account = containerArn.split(":")[4];
+      }
+    }
+
+    Optional<String> getLogGroupArn() {
+      if (region == null || account == null || logGroupName == null) {
+        return Optional.empty();
+      }
+
+      return Optional.of("arn:aws:logs:" + region + ":" + account + ":log-group:" + logGroupName);
+    }
+
+    Optional<String> getLogStreamArn() {
+      if (region == null || account == null || logGroupName == null || logStreamName == null) {
+        return Optional.empty();
+      }
+
+      return Optional.of(
+          "arn:aws:logs:"
+              + region
+              + ":"
+              + account
+              + ":log-group:"
+              + logGroupName
+              + ":log-stream:"
+              + logStreamName);
+    }
   }
 
-  private EcsResource() {}
+  /** This can parse a Docker image name into its parts: repository, tag and sha256. */
+  private static class DockerImage {
+
+    private static final Pattern imagePattern =
+        Pattern.compile(
+            "^(?<repository>([^/\\s]+/)?([^:\\s]+))(:(?<tag>[^@\\s]+))?(@sha256:(?<sha256>\\d+))?$");
+
+    final String repository;
+    final String tag;
+
+    private DockerImage(String repository, String tag) {
+      this.repository = repository;
+      this.tag = tag;
+    }
+
+    String getRepository() {
+      return repository;
+    }
+
+    String getTag() {
+      return tag;
+    }
+
+    @Nullable
+    static DockerImage parse(@Nullable String image) {
+      if (image == null || image.isEmpty()) {
+        return null;
+      }
+      Matcher matcher = imagePattern.matcher(image);
+      if (!matcher.matches()) {
+        logger.log(Level.WARNING, "Couldn't parse image '" + image + "'");
+        return null;
+      }
+      String repository = matcher.group("repository");
+      String tag = matcher.group("tag");
+      if (tag == null || tag.isEmpty()) {
+        tag = "latest";
+      }
+      return new DockerImage(repository, tag);
+    }
+  }
 }