VictoriaMetrics/VictoriaMetrics · error

cannot parse server url=%q: %w

Error message

cannot parse server url=%q: %w

What it means

getAPIServerPath parses the (scheme-prefixed) server URL with net/url.Parse. If parsing fails, the error is wrapped with this message including the full server string. It means the Kuma control-plane URL is syntactically invalid even after the automatic http:// prefixing.

Source

Thrown at lib/promscrape/discovery/kuma/api.go:113

		return nil, fmt.Errorf("cannot discover Kuma targets: %w", err)
	}
	cfg.wg.Go(func() {
		cfg.runTargetsWatcher(ctx)
	})

	return cfg, nil
}

func getAPIServerPath(serverURL string) (string, string, error) {
	if serverURL == "" {
		return "", "", fmt.Errorf("missing server url")
	}
	if !strings.Contains(serverURL, "://") {
		serverURL = "http://" + serverURL
	}
	psu, err := url.Parse(serverURL)
	if err != nil {
		return "", "", fmt.Errorf("cannot parse server url=%q: %w", serverURL, err)
	}
	apiServer := fmt.Sprintf("%s://%s", psu.Scheme, psu.Host)
	apiPath := psu.Path
	if !strings.HasSuffix(apiPath, "/") {
		apiPath += "/"
	}
	apiPath += "v3/discovery:monitoringassignments"
	if psu.RawQuery != "" {
		apiPath += "?" + psu.RawQuery
	}
	return apiServer, apiPath, nil
}

func (cfg *apiConfig) runTargetsWatcher(ctx context.Context) {
	ticker := time.NewTicker(*SDCheckInterval)
	defer ticker.Stop()

	doneCh := ctx.Done()

View on GitHub (pinned to 5079fb58f1)

Solutions

1. Fix the `server` value so it parses as a URL (quote it in YAML, remove spaces/control chars)
2. Wrap IPv6 hosts in brackets: `http://[::1]:5676`
3. Pre-validate with Go url.Parse or any URL validator before deploying the config
4. Read the wrapped error to see url.Parse's exact complaint (e.g. invalid port, invalid character)

Example fix

# before
server: http://kuma cp:5676   # unquoted, contains space
# after
server: "http://kuma-cp:5676"

func validKumaURL(server string) error {
    if server == "" {
        return errors.New("missing server url")
    }
    u := server
    if !strings.Contains(u, "://") {
        u = "http://" + u
    }
    psu, err := url.Parse(u)
    if err != nil {
        return fmt.Errorf("invalid server url %q: %w", server, err)
    }
    if psu.Host == "" {
        return fmt.Errorf("server url %q has no host", server)
    }
    return nil
}

ac, err := kuma.NewSDConfig(sdc)
if err != nil {
    if strings.Contains(err.Error(), "cannot parse server url") {
        log.Errorf("malformed kuma server URL: %v", err)
    }
    return err
}

When it happens

Trigger: Server string containing spaces, control characters, stray brackets/quotes, or otherwise failing url.Parse (e.g. `server: "http://kuma cp:5676"`), when getAPIServerPath runs.

Common situations: Unquoted YAML values with special characters; copy-pasted URLs with trailing whitespace; IPv6 literal addresses missing brackets; templating artifacts left in the URL.

Related errors

• cannot parse server %q: %w
• cannot create HTTP client for %q: %w
• missing server url
• cannot parse auth config: %w
• cannot parse proxy auth config: %w

AI-assisted analysis of VictoriaMetrics/VictoriaMetrics@5079fb58f1 (2026-09-03). Data as JSON: /api/errors/983525d1ca107975. Report an issue: GitHub.