handle empty tags, add tests and close underlying body

Signed-off-by: Kavindu Dodanduwa <[email protected]>

Author: Kavindu-Dodan

libbeat/processors/add_cloud_metadata/provider_aws_ec2.go

@@ -153,7 +153,7 @@ func getTags(ctx context.Context, imdsClient IMDSClient, ec2Client EC2Client, in
 	logger.Info("Tag extraction from IMDS failed, fallback to DescribeTags API to obtain EKS cluster name.")
 	clusterName, err := clusterNameFromDescribeTag(ctx, ec2Client, instanceId)
 	if err != nil {
-		logger.Warnf("error obtaining cluster name: %s.", err)
+		logger.Warnf("error obtaining cluster name: %v.", err)
 		return tags
 	}
 
@@ -169,36 +169,52 @@ func getTags(ctx context.Context, imdsClient IMDSClient, ec2Client EC2Client, in
 func getTagsFromIMDS(ctx context.Context, client IMDSClient, logger *logp.Logger) (tags map[string]string, ok bool) {
 	tags = make(map[string]string)
 
-	metadata, err := client.GetMetadata(ctx, &imds.GetMetadataInput{Path: tagsCategory})
+	b, err := getMetadataHelper(ctx, client, tagsCategory, logger)
 	if err != nil {
-		logger.Warnf("error from IMDS tags category request: %s", err)
+		logger.Warnf("error obtaining tags category: %v", err)
 		return tags, false
 	}
 
-	b, err := io.ReadAll(metadata.Content)
-	if err != nil {
-		logger.Warnf("error extracting tags category payload: %s", err)
-		return tags, false
+	tagInput := string(b)
+	if tagInput == "" {
+		logger.Info("No tags present in the EC2 instance")
+		return tags, true
 	}
 
-	for _, tag := range strings.Split(string(b), "\n") {
+	for _, tag := range strings.Split(tagInput, "\n") {
 		tagPath := fmt.Sprintf("%s/%s", tagsCategory, tag)
-		metadata, err := client.GetMetadata(ctx, &imds.GetMetadataInput{Path: tagPath})
+		b, err := getMetadataHelper(ctx, client, tagPath, logger)
 		if err != nil {
-			logger.Warnf("error from IMDS tag request: %s", err)
+			logger.Warnf("error extracting tag value of %s: %v", tag, err)
 			return tags, false
 		}
 
-		b, err := io.ReadAll(metadata.Content)
+		tags[tag] = string(b)
+	}
+
+	return tags, true
+}
+
+// getMetadataHelper performs the IMDS call for the given path and returns the response content after closing the underlying content reader.
+func getMetadataHelper(ctx context.Context, client IMDSClient, path string, logger *logp.Logger) (content []byte, err error) {
+	metadata, err := client.GetMetadata(ctx, &imds.GetMetadataInput{Path: path})
+	if err != nil {
+		return nil, fmt.Errorf("error from IMDS metadata request: %w", err)
+	}
+
+	defer func(Content io.ReadCloser) {
+		err := Content.Close()
 		if err != nil {
-			logger.Warnf("error extracting tag value payload: %s", err)
-			return tags, false
+			logger.Warnf("error closing IMDS metadata response body: %v", err)
 		}
+	}(metadata.Content)
 
-		tags[tag] = string(b)
+	content, err = io.ReadAll(metadata.Content)
+	if err != nil {
+		return nil, fmt.Errorf("error extracting metadata from the IMDS response: %w", err)
 	}
 
-	return tags, true
+	return content, nil
 }
 
 // clusterNameFromDescribeTag is a helper to extract EKS cluster name using DescribeTag.

libbeat/processors/add_cloud_metadata/provider_aws_ec2_test.go

@@ -482,6 +482,19 @@ func Test_getTags(t *testing.T) {
 				}},
 			want: map[string]string{},
 		},
+		{
+			name: "Empty tags results in empty tag extraction",
+			imdsClient: &MockIMDSClient{
+				GetMetadataFunc: func(ctx context.Context, input *imds.GetMetadataInput, f ...func(*imds.Options)) (*imds.GetMetadataOutput, error) {
+					return &imds.GetMetadataOutput{Content: io.NopCloser(strings.NewReader(""))}, nil
+				},
+			},
+			ec2Client: &MockEC2Client{
+				DescribeTagsFunc: func(ctx context.Context, params *ec2.DescribeTagsInput, optFns ...func(*ec2.Options)) (*ec2.DescribeTagsOutput, error) {
+					return nil, errors.New("some error from DescribeTag")
+				}},
+			want: map[string]string{},
+		},
 	}
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {