What causes "base URL accessibility test failed: %w" in Billionmail/BillionMail?

Inspect the wrapped inner error to identify the exact network cause (DNS, refused, timeout, TLS)

base URL accessibility test failed: %w

Error message

base URL accessibility test failed: %w

What it means

Testing probes base URL reachability with a HEAD request via testBaseURLAccessibility. Any failure — DNS failure, connection refused, timeout, TLS error, or non-success status — is wrapped as 'base URL accessibility test failed: %w'. The wrapped cause contains the real network error.

Source

Thrown at core/internal/service/askai/supplier.go:497

// 2. Tests the accessibility of the base URL by sending a HEAD request.
// 3. Validates the API key by sending a GET request to the models endpoint.
// If any of these checks fail, it returns an error indicating the issue.
func Testing(supplierName, baseUrl, apiKey string) error {
	if supplierName == "" || baseUrl == "" || apiKey == "" {
		return errors.New("supplier name, base URL, and API key are required")
	}

	// Validate base URL format
	parsedUrl, err := url.ParseRequestURI(baseUrl)
	if err != nil {
		return fmt.Errorf("invalid base URL format: %w", err)
	}
	if parsedUrl.Scheme != "http" && parsedUrl.Scheme != "https" {
		return errors.New("base URL must use http or https protocol")
	}
	// Ensure the base URL ends with a slash
	if err := testBaseURLAccessibility(baseUrl); err != nil {
		return fmt.Errorf("base URL accessibility test failed: %w", err)
	}
	// Validate API key by making a request to the models endpoint
	if err := testAPIKeyValidity(baseUrl, apiKey); err != nil {
		return fmt.Errorf("API key validation failed: %w", err)
	}

	return nil
}

// testBaseURLAccessibility checks if the base URL is accessible by sending a HEAD request.
// It returns an error if the request fails or if the response status is not OK (200).
func testBaseURLAccessibility(baseUrl string) error {
	client := &http.Client{Timeout: 3 * time.Second}
	resp, err := client.Head(baseUrl)
	if err != nil {
		return err
	}
	defer resp.Body.Close()

View on GitHub (pinned to fc36c76c05)

Solutions

Inspect the wrapped inner error to identify the exact network cause (DNS, refused, timeout, TLS)
Confirm the URL is reachable: curl -I <baseUrl> from the same host/network
Check DNS, firewall, and proxy settings; for containers verify network reachability
Verify the server accepts HEAD requests or correct the endpoint URL
Fix TLS certificate issues or use http:// for local-only endpoints

Example fix

// before
err := askai.Testing(name, "http://localhost:9999/v1", key) // server not running
// after
// start the service first, or use the correct port
if err := exec.Command("curl", "-sfI", baseURL); err != nil { /* fix reachability */ }
err := askai.Testing(name, "http://localhost:8080/v1", key)

Defensive patterns

Strategy: retry

Validate before calling

func baseURLReachable(raw string) error {
    ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
    defer cancel()
    req, err := http.NewRequestWithContext(ctx, http.MethodHead, raw, nil)
    if err != nil { return err }
    resp, err := http.DefaultClient.Do(req)
    if err != nil { return err }
    resp.Body.Close()
    return nil
}
// call before askai.Testing to fail fast with a clearer error

Try / catch

var err error
for attempt := 0; attempt < 3; attempt++ {
    err = askai.Testing(name, baseUrl, apiKey)
    if err == nil || !strings.Contains(err.Error(), "accessibility test failed") { break }
    time.Sleep(time.Duration(1<<attempt) * time.Second)
}
if err != nil { return fmt.Errorf("supplier endpoint unreachable: %w", err) }

Prevention

Verify the endpoint with curl -I from the same host/network before testing
Check DNS, firewall, and proxy configuration in the deployment environment
Confirm the service is running and the port is correct (esp. in Docker networks)
Keep reasonable timeouts and retry transient network failures

When it happens

Trigger: Calling askai.Testing against a host that is down, unreachable, behind a firewall, has expired TLS certificates, or returns an error HTTP status to HEAD requests.

Common situations: Typo'd hostname or wrong port; server running locally but Testing called in an environment without access (Docker network mismatch); corporate proxy blocking the request; self-signed/expired certs; endpoint only supports GET, not HEAD.

Related errors

AI-assisted analysis of Billionmail/BillionMail@fc36c76c05 (2026-09-05). Data as JSON: /api/errors/02aa881a58c59b62. Report an issue: GitHub.