Better handling of concurrent printing

internal/builders/docker/pkg/builder.go

@@ -480,34 +480,34 @@ func (c *GitClient) checkoutGitCommit() error {
 
 type TempFileResult struct {
 	File *os.File
-	Err error
+	Err  error
 }
 
 // A helper function used by saveToTempFile to process one individual file.
-func saveOneTempFile(verbose bool, reader io.Reader, ch chan TempFileResult) {
-		var allBytes []byte
-		scanner := bufio.NewScanner(reader)
-		for scanner.Scan() {
-			bytes := scanner.Bytes()
-			allBytes = append(allBytes, bytes...)
-			allBytes = append(allBytes, '\n')
-
-			if verbose {
-				fmt.Printf("%s\n", bytes)
-			}
+func saveOneTempFile(verbose bool, reader io.Reader, fileChannel chan TempFileResult, printChannel chan string) {
+	var allBytes []byte
+	scanner := bufio.NewScanner(reader)
+	for scanner.Scan() {
+		bytes := scanner.Bytes()
+		allBytes = append(allBytes, bytes...)
+		allBytes = append(allBytes, '\n')
+
+		if verbose {
+			printChannel <- string(bytes)
 		}
+	}
 
-		tmpfile, err := os.CreateTemp("", "log-*.txt")
-		if err != nil {
-			ch <- TempFileResult { Err: err }
-			return
-		}
-		if _, err := tmpfile.Write(allBytes); err != nil {
-			tmpfile.Close()
-			ch <- TempFileResult { Err: fmt.Errorf("couldn't write bytes to tempfile: %v", err) }
-		}
+	tmpfile, err := os.CreateTemp("", "log-*.txt")
+	if err != nil {
+		fileChannel <- TempFileResult{Err: err}
+		return
+	}
+	if _, err := tmpfile.Write(allBytes); err != nil {
+		tmpfile.Close()
+		fileChannel <- TempFileResult{Err: fmt.Errorf("couldn't write bytes to tempfile: %v", err)}
+	}
 
-		ch <- TempFileResult { File: tmpfile }
+	fileChannel <- TempFileResult{File: tmpfile}
 }
 
 // saveToTempFile creates a tempfile in `/tmp` and writes the content of the
@@ -518,24 +518,30 @@ func saveToTempFile(verbose bool, readers ...io.Reader) ([]string, error) {
 		fmt.Print("\n\n>>>>>>>>>>>>>> output from command <<<<<<<<<<<<<<\n")
 	}
 	var wg sync.WaitGroup
-	var ch = make(chan TempFileResult, len(readers))
+	var fileChannel = make(chan TempFileResult, len(readers))
+	var printChannel = make(chan string)
 
 	for _, reader := range readers {
 		wg.Add(1)
 		go func(reader io.Reader) {
 			defer wg.Done()
-			saveOneTempFile(verbose, reader, ch)
+			saveOneTempFile(verbose, reader, fileChannel, printChannel)
 		}(reader)
 	}
 
 	// Close the channel once all goroutines have finished.
 	go func() {
 		wg.Wait()
-		close(ch)
+		close(printChannel)
+		close(fileChannel)
 	}()
 
+	for line := range printChannel {
+		fmt.Println(line)
+	}
+
 	var files []string
-	for result := range ch {
+	for result := range fileChannel {
 		if result.Err != nil {
 			return nil, result.Err
 		}