feat: enhances S3Download to filter by traced table names (#1374)

This PR updates the `S3Download` implementation to allow specifying the
names of the traced tables when downloading from an S3 bucket. This
enhancement enables file filtering and reduces the amount of data
downloaded. It is a desirable feature when interacting with the traced
data of large network tests. If no table name is provided, then
`S3Download` downloads all the traced tables.

pkg/trace/fileserver.go

@@ -259,7 +259,9 @@ func (lt *LocalTracer) PushAll() error {
 
 // S3Download downloads files that match some prefix from an S3 bucket to a
 // local directory dst.
-func S3Download(dst, prefix string, cfg S3Config) error {
+// fileNames is a list of traced jsonl file names to download. If it is empty, all traces are downloaded.
+// fileNames should not have .jsonl suffix.
+func S3Download(dst, prefix string, fileNames []string, cfg S3Config) error {
 	// Ensure local directory structure exists
 	err := os.MkdirAll(dst, os.ModePerm)
 	if err != nil {
@@ -288,37 +290,51 @@ func S3Download(dst, prefix string, cfg S3Config) error {
 
 	err = s3Svc.ListObjectsV2Pages(input, func(page *s3.ListObjectsV2Output, lastPage bool) bool {
 		for _, content := range page.Contents {
-			localFilePath := filepath.Join(dst, prefix, strings.TrimPrefix(*content.Key, prefix))
-			fmt.Printf("Downloading %s to %s\n", *content.Key, localFilePath)
+			key := *content.Key
 
-			// Create the directories in the path
-			if err := os.MkdirAll(filepath.Dir(localFilePath), os.ModePerm); err != nil {
-				return false
+			// If no fileNames are specified, download all files
+			if len(fileNames) == 0 {
+				fileNames = append(fileNames, strings.TrimPrefix(key, prefix))
 			}
 
-			// Create a file to write the S3 Object contents to.
-			f, err := os.Create(localFilePath)
-			if err != nil {
-				return false
-			}
-
-			resp, err := s3Svc.GetObject(&s3.GetObjectInput{
-				Bucket: aws.String(cfg.BucketName),
-				Key:    aws.String(*content.Key),
-			})
-			if err != nil {
-				f.Close()
-				continue
+			for _, filename := range fileNames {
+				// Add .jsonl suffix to the fileNames
+				fullFilename := filename + ".jsonl"
+				if strings.HasSuffix(key, fullFilename) {
+					localFilePath := filepath.Join(dst, prefix, strings.TrimPrefix(key, prefix))
+					fmt.Printf("Downloading %s to %s\n", key, localFilePath)
+
+					// Create the directories in the path
+					if err := os.MkdirAll(filepath.Dir(localFilePath), os.ModePerm); err != nil {
+						return false
+					}
+
+					// Create a file to write the S3 Object contents to.
+					f, err := os.Create(localFilePath)
+					if err != nil {
+						return false
+					}
+
+					resp, err := s3Svc.GetObject(&s3.GetObjectInput{
+						Bucket: aws.String(cfg.BucketName),
+						Key:    aws.String(key),
+					})
+					if err != nil {
+						f.Close()
+						continue
+					}
+					defer resp.Body.Close()
+
+					// Copy the contents of the S3 object to the local file
+					if _, err := io.Copy(f, resp.Body); err != nil {
+						f.Close()
+						return false
+					}
+
+					fmt.Printf("Successfully downloaded %s to %s\n", key, localFilePath)
+					f.Close()
+				}
 			}
-			defer resp.Body.Close()
-
-			// Copy the contents of the S3 object to the local file
-			if _, err := io.Copy(f, resp.Body); err != nil {
-				return false
-			}
-
-			fmt.Printf("Successfully downloaded %s to %s\n", *content.Key, localFilePath)
-			f.Close()
 		}
 		return !lastPage // continue paging
 	})