grafana/k6 · error

secret response exceeds maximum size of %d bytes

Error message

secret response exceeds maximum size of %d bytes

What it means

The body returned by the remote secret endpoint exceeded the 24 KiB safety cap enforced by extractSecretFromResponse. Reading is deliberately limited (io.LimitReader with maxSecretSize+1) to prevent memory exhaustion from huge responses; seeing maxSecretSize+1 bytes means the response is larger than a secret should ever be.

Source

Thrown at internal/secretsource/url/url.go:245

	// the interval of time after which a new token is replenished. In
	// other words, the units are time unit/token.
	tokenReplenishInterval := time.Minute / time.Duration(requestsPerMinuteLimit)

	return rate.NewLimiter(rate.Every(tokenReplenishInterval), requestsBurst)
}

func extractSecretFromResponse(body io.Reader, responsePath string) (string, error) {
	const maxSecretSize = 24 * 1024

	// Limit reading to prevent memory exhaustion from large responses
	limitedReader := io.LimitReader(body, maxSecretSize+1)
	data, err := io.ReadAll(limitedReader)
	if err != nil {
		return "", fmt.Errorf("failed to read response body: %w", err)
	}

	if len(data) > maxSecretSize {
		return "", fmt.Errorf("secret response exceeds maximum size of %d bytes", maxSecretSize)
	}

	if responsePath == "" {
		// If no path specified, assume response body is the secret
		return string(data), nil
	}

	result := gjson.GetBytes(data, responsePath)

	if !result.Exists() {
		return "", fmt.Errorf("path %q not found in response", responsePath)
	}

	if result.Type != gjson.String {
		return "", fmt.Errorf("secret value at path %q is not a string (got %s)", responsePath, result.Type)
	}

	return result.String(), nil

View on GitHub (pinned to 01ffac6f24)

Solutions

1. Configure responsePath so only a small JSON field is extracted instead of the whole body
2. Fix the service endpoint if it is returning an unexpectedly large payload

When it happens

Trigger: Thrown at internal/secretsource/url/url.go:245 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of grafana/k6@01ffac6f24 (2026-08-18). Data as JSON: /api/errors/6f553c2e6b0a9562. Report an issue: GitHub.