googleapis/mcp-toolbox · error

error performing request: %w

Error message

error performing request: %w

What it means

Thrown by the Dgraph source's healthCheck when hc.httpClient.Do(req) fails, meaning the HTTP GET to the Dgraph /health endpoint could not be completed. The underlying transport error (DNS, dial, timeout, TLS) is wrapped with %w. This signals a network-level failure reaching the Dgraph Zero/Alpha, not an HTTP error status.

Source

Thrown at internal/sources/dgraph/dgraph.go:354

	hc.AccessJwt = r.Data.AccessJWT
	hc.RefreshToken = r.Data.RefreshJWT
	return nil
}

func (hc *DgraphClient) healthCheck() error {
	url, err := getUrl(hc.baseUrl, "/health", nil)
	if err != nil {
		return err
	}
	req, err := http.NewRequest(http.MethodGet, url, nil)
	if err != nil {
		return fmt.Errorf("error creating request: %w", err)
	}

	resp, err := hc.httpClient.Do(req)
	if err != nil {
		return fmt.Errorf("error performing request: %w", err)
	}

	defer resp.Body.Close()
	data, err := io.ReadAll(resp.Body)
	if err != nil {
		return err
	}
	var result []struct {
		Instance string `json:"instance"`
		Address  string `json:"address"`
		Status   string `json:"status"`
	}

	// Unmarshal response into the struct
	if err := json.Unmarshal(data, &result); err != nil {
		return fmt.Errorf("failed to unmarshal json: %v", err)
	}

View on GitHub (pinned to 8cc6e09de2)

Solutions

1. Verify Dgraph is running and reachable: curl http://<host>:<port>/health from the toolbox host/container.
2. Correct the baseUrl host/port in the Dgraph source configuration.
3. If containers are involved, confirm both are on the same Docker/Kubernetes network.
4. If intermittent, retry; persistent failures indicate connectivity or service-down issues.

Example fix

// before
baseUrl: http://localhost:8080  // dgraph runs in another container
// after
baseUrl: http://dgraph:8080  // use the service name on the shared network

// reachability probe before initializing the source
resp, err := http.Get("http://dgraph:8080/health")
if err != nil {
    return fmt.Errorf("dgraph unreachable at :8080: %w", err)
}
resp.Body.Close()

if err := healthCheck(ctx); err != nil {
    if strings.Contains(err.Error(), "error performing request") {
        // transient network failure: retry with backoff
        return retryWithBackoff(3, 2*time.Second, healthCheck)
    }
    return err
}

When it happens

Trigger: healthCheck calls hc.httpClient.Do(req) against baseUrl + "/health" and the request fails before a response is returned: connection refused, DNS resolution failure, TLS handshake error, or context deadline exceeded.

Common situations: Dgraph container not running or crashed, wrong host/port in baseUrl, service in a different Docker network/namespace, firewall or network policy blocking the port, or the health check timing out under load.

Understand the failure class

Background: ECONNREFUSED and "connection refused" / "could not connect to server" errors: what they mean and how to fix them — this error's family across 44 libraries.

Related errors

• failed to fetch OIDC config: %w
• failed to read introspection response: %w
• failed to read response body: %w
• failed to execute request: %w
• error parsing JSON: %v

AI-assisted analysis of googleapis/mcp-toolbox@8cc6e09de2 (2026-09-05). Data as JSON: /api/errors/986e944a662506f7. Report an issue: GitHub.