What causes "creating IMDS request: %w" in kubernetes/kops?

Inspect the wrapped error; it names the URL parse failure — fix the offending constant/path value

creating IMDS request: %w

Error message

creating IMDS request: %w

What it means

queryIMDS failed to construct the *http.Request via http.NewRequestWithContext for the IMDS URL. The error is wrapped as "creating IMDS request". In practice this is nearly impossible here since the URL is the constant imdsBaseURL plus a static path, so it usually signals an internal/programming problem rather than an environment issue.

Source

Thrown at upup/pkg/fi/cloudup/azure/azuremetadata/imds.go:69

// InstanceMetadata contains compute instance metadata from the Azure IMDS.
type InstanceMetadata struct {
	SubscriptionID    string `json:"subscriptionId"`
	ResourceGroupName string `json:"resourceGroupName"`
	ResourceID        string `json:"resourceId"`
	VMID              string `json:"vmId"`
}

// attestedDocument is the JSON response from the IMDS attested/document endpoint.
type attestedDocument struct {
	Signature string `json:"signature"`
}

// queryIMDS queries an Azure IMDS endpoint and unmarshals the JSON response.
// https://learn.microsoft.com/en-us/azure/virtual-machines/instance-metadata-service
func queryIMDS(ctx context.Context, path string, params url.Values, result any) error {
	req, err := http.NewRequestWithContext(ctx, "GET", imdsBaseURL+path, nil)
	if err != nil {
		return fmt.Errorf("creating IMDS request: %w", err)
	}
	req.Header.Add("Metadata", "True")

	params.Set("api-version", imdsAPIVersion)
	req.URL.RawQuery = params.Encode()

	klog.V(4).Infof("Azure IMDS query: %q", req.URL.String())

	resp, err := imdsHTTPClient.Do(req)
	if err != nil {
		return fmt.Errorf("querying IMDS %s: %w", path, err)
	}
	defer resp.Body.Close()

	if resp.StatusCode != http.StatusOK {
		return fmt.Errorf("querying IMDS %s: status %d", path, resp.StatusCode)
	}

View on GitHub (pinned to 4c8573c808)

Solutions

Inspect the wrapped error; it names the URL parse failure — fix the offending constant/path value
Validate that imdsBaseURL and the caller-provided path form a valid absolute URL
Add a unit test covering queryIMDS with all call sites' paths

Example fix

// before
imdsBaseURL = "169.254.169.254" // missing scheme -> request creation fails
// after
imdsBaseURL = "http://169.254.169.254"

Defensive patterns

Strategy: validation

Validate before calling

// Ensure the IMDS URL is well-formed before calling queryIMDS
if _, err := url.Parse(imdsBaseURL + "/metadata/instance/compute"); err != nil {
    return fmt.Errorf("invalid IMDS base URL configured: %w", err)
}

Prevention

Keep imdsBaseURL as a compile-time constant; never build it from user input
Add a unit test asserting http.NewRequest succeeds for every IMDS path used
Run go vet/lint on changes touching URL constants

When it happens

Trigger: http.NewRequestWithContext returns an error for imdsBaseURL+path — e.g. a malformed URL string, which would only happen if imdsBaseURL or the path constants were changed to invalid values, or ctx is invalid.

Common situations: Code modification introducing a bad base URL or path (typos, illegal characters); misuse of the function with a path containing characters that break URL parsing; otherwise essentially never in production binaries.

Related errors

AI-assisted analysis of kubernetes/kops@4c8573c808 (2026-09-05). Data as JSON: /api/errors/065facf665730744. Report an issue: GitHub.