GoogleContainerTools/skaffold · warning

writing string to temporary buffer: %w

Error message

writing string to temporary buffer: %w

What it means

While building the log text in memory, SaveLastLog appends each ANSI-stripped SkaffoldLogEvent message to a bytes.Buffer via contents.WriteString. This error wraps a failure of that in-memory write, which in Go only happens when the buffer cannot grow (bytes.ErrTooLarge — exceeding maxBufferCapacity or an out-of-memory allocation).

Source

Thrown at pkg/skaffold/event/v2/event.go:366

	}
	// Ensure that the filepath provided has the directories available when attemping to save the file.
	dir := filepath.Dir(fp)
	if err := os.MkdirAll(dir, 0700); err != nil {
		return fmt.Errorf("unable to create directory %q: %w", dir, err)
	}
	f, err := os.OpenFile(fp, os.O_TRUNC|os.O_WRONLY|os.O_CREATE, 0600)
	if err != nil {
		return fmt.Errorf("opening %s: %w", fp, err)
	}
	defer f.Close()

	// Iterate over events, grabbing contents only from SkaffoldLogEvents
	var contents bytes.Buffer
	for _, ev := range handler.eventLog {
		if sle := ev.GetSkaffoldLogEvent(); sle != nil {
			// Strip ansi color sequences as this makes it easier to deal with when pasting into github issues
			if _, err = contents.WriteString(stripansi.Strip(sle.Message)); err != nil {
				return fmt.Errorf("writing string to temporary buffer: %w", err)
			}
		}
	}

	// Write contents of temporary buffer to file
	if _, err = f.Write(contents.Bytes()); err != nil {
		return fmt.Errorf("writing buffer contents to file: %w", err)
	}
	return nil
}

func lastLogFile(fp string) (string, error) {
	if fp != "" {
		return fp, nil
	}

	// last log location unspecified, use ~/.skaffold/last.log
	home, err := homedir.Dir()

View on GitHub (pinned to a1189de023)

Solutions

1. Restart the skaffold session / clear handler.eventLog so the buffer starts small.
2. Reduce log verbosity or the number of retained SkaffoldLogEvents before saving.
3. Stream events to the file incrementally instead of buffering everything in memory first.

Example fix

// before
var contents bytes.Buffer
for _, ev := range handler.eventLog { /* buffer everything */ }
f.Write(contents.Bytes())
// after
for _, ev := range handler.eventLog {
    if sle := ev.GetSkaffoldLogEvent(); sle != nil {
        f.WriteString(stripansi.Strip(sle.Message)) // stream directly
    }
}

total := 0
for _, ev := range handler.eventLog {
    if sle := ev.GetSkaffoldLogEvent(); sle != nil {
        total += len(sle.Message)
    }
}
if total > 1<<30 {
    return errors.New("event log exceeds 1GiB; trim before saving")
}

if err := event.SaveLastLog(fp); err != nil {
    if strings.Contains(err.Error(), "temporary buffer") {
        log.Warnf("log too large to buffer: %v", err)
        return streamEventsToFile(fp) // custom streaming writer
    }
    return err
}

When it happens

Trigger: Calling SaveLastLog after a very long skaffold run whose accumulated SkaffoldLogEvent messages exceed bytes.Buffer's maximum capacity (~large GB), or a genuine memory-allocation failure during buffer growth.

Common situations: Extremely long-running debug/dev sessions with verbose logging accumulating gigabytes of log events; memory-constrained environments where a single buffer growth allocation fails.

Related errors

• reading %q in embedded filesystem: %w
• creating tar gz: %w
• writing string: %w
• writing string: %w
• writing buffer contents to file: %w

AI-assisted analysis of GoogleContainerTools/skaffold@a1189de023 (2026-09-05). Data as JSON: /api/errors/c7371401845629a1. Report an issue: GitHub.