grafana/k6 · error

failed to read config file: %w

Error message

failed to read config file: %w

What it means

loadConfigFromFile opened the JSON config file for the URL secret source successfully but io.ReadAll failed while streaming its contents, e.g. an actual I/O error on the filesystem. Distinguishes read failures from the separate open and unmarshal errors emitted by the same function.

Source

Thrown at internal/secretsource/url/url.go:507

				cfg.Headers = make(map[string]string)
			}
			cfg.Headers[headerName] = value
		}
	}

	return cfg, nil
}

func loadConfigFromFile(configPath string, fs fsext.Fs) (extConfig, error) {
	file, err := fs.Open(configPath)
	if err != nil {
		return extConfig{}, fmt.Errorf("failed to open config file: %w", err)
	}
	defer func() { _ = file.Close() }()

	configData, err := io.ReadAll(file)
	if err != nil {
		return extConfig{}, fmt.Errorf("failed to read config file: %w", err)
	}

	var fileCfg extConfig
	if err := json.Unmarshal(configData, &fileCfg); err != nil {
		return extConfig{}, fmt.Errorf("failed to parse JSON config: %w", err)
	}

	return fileCfg, nil
}

func validateURLTemplate(urlTemplate string) error {
	if urlTemplate == "" {
		return errMissingURLTemplate
	}

	// Require {key} placeholder to differentiate between secrets
	if !strings.Contains(urlTemplate, "{key}") {
		return errors.New("urlTemplate must contain {key} placeholder")

View on GitHub (pinned to 01ffac6f24)

Solutions

1. Retry after checking disk/file accessibility
2. Ensure the file isn't being modified concurrently while k6 reads it

When it happens

Trigger: Thrown at internal/secretsource/url/url.go:507 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/0b1fa7c0f5fb11df. Report an issue: GitHub.