googleapis/mcp-toolbox · error

failed to get url %v

Error message

failed to get url %v

What it means

Thrown by getUrl in the Dgraph source when url.ParseRequestURI(baseUrl) fails, so a request URL cannot be built for any operation (postDqlQuery, mutate, doLogin, healthCheck all call it). It means the configured baseUrl is not a parseable absolute URI. The parse error is wrapped with %v.

Source

Thrown at internal/sources/dgraph/dgraph.go:393

	}

	var unhealthyErr error
	for _, info := range result {
		if info.Status != "healthy" {
			unhealthyErr = fmt.Errorf("dgraph instance [%v] is not in healthy state, address is %v",
				info.Instance, info.Address)
		} else {
			return nil
		}
	}

	return unhealthyErr
}

func getUrl(baseUrl, resource string, params url.Values) (string, error) {
	u, err := url.ParseRequestURI(baseUrl)
	if err != nil {
		return "", fmt.Errorf("failed to get url %v", err)
	}
	u.Path = resource
	u.RawQuery = params.Encode()
	return u.String(), nil
}

func checkError(resp []byte) error {
	var errResp struct {
		Errors []struct {
			Message string `json:"message"`
		} `json:"errors"`
	}

	if err := json.Unmarshal(resp, &errResp); err != nil {
		return fmt.Errorf("failed to unmarshal json: %v", err)
	}

	if len(errResp.Errors) > 0 {

View on GitHub (pinned to 8cc6e09de2)

Solutions

1. Set the Dgraph source's baseUrl to a full absolute URL with scheme, e.g. http://dgraph:8080 (HTTP port, not gRPC 9080).
2. Check that any environment variable used for the host actually resolves to a non-empty value.
3. Trim whitespace/quotes from the configured URL.
4. Validate locally: run the same URL through a URL parser or curl before restarting the toolbox.

Example fix

// before
address: dgraph:9080
// after
address: http://dgraph:8080

u, err := url.ParseRequestURI(cfg.Address)
if err != nil {
    return fmt.Errorf("dgraph address %q is not a valid absolute URI (use http://host:8080)", cfg.Address)
}
_ = u

url, err := getUrl(base, "/health", nil)
if err != nil {
    if strings.Contains(err.Error(), "failed to get url") {
        return fmt.Errorf("check the dgraph address in your config: %w", err)
    }
    return err
}

When it happens

Trigger: Any Dgraph operation calls getUrl(baseUrl, resource, params) and url.ParseRequestURI rejects the baseUrl because it lacks a scheme, contains spaces/control chars, or is otherwise malformed.

Common situations: Missing http:// scheme in the config (e.g. "localhost:8080" or "dgraph:9080" — the gRPC port), environment variable interpolation leaving the value empty, or copying a URL with surrounding quotes/spaces.

Related errors

• error creating request: %w
• doc %d: unexpected non-string key in input: %v
• doc %d: invalid config format at key %q: %w
• doc %d: invalid config format at key %q: expected nested for
• invalid auth URL

AI-assisted analysis of googleapis/mcp-toolbox@8cc6e09de2 (2026-09-05). Data as JSON: /api/errors/53de6e88720416fb. Report an issue: GitHub.