Validate Distributor endpoints before publication

internal/config/validate.go

@@ -119,9 +119,8 @@ func validateDistributorNotify(cfg DistributorNotifyConfig) error {
 		return nil
 	}
 
-	parsed, err := url.Parse(cfg.Endpoint)
-	if err != nil || parsed.Scheme == "" || parsed.Host == "" {
-		return fmt.Errorf("notify.distributor.endpoint must be an absolute URL when enabled")
+	if err := ValidateDistributorEndpoint(cfg.Endpoint); err != nil {
+		return fmt.Errorf("notify.distributor.endpoint %w", err)
 	}
 	if cfg.TokenEnv == "" {
 		return fmt.Errorf("notify.distributor.token_env is required when enabled")
@@ -172,6 +171,25 @@ func validateDistributorNotify(cfg DistributorNotifyConfig) error {
 	return nil
 }
 
+// ValidateDistributorEndpoint verifies the endpoint grammar accepted by the
+// pinned Distributor upload client.
+func ValidateDistributorEndpoint(endpoint string) error {
+	parsed, err := url.Parse(endpoint)
+	if err != nil || parsed.Scheme == "" || parsed.Host == "" {
+		return fmt.Errorf("must be an absolute URL")
+	}
+	if parsed.Scheme != "http" && parsed.Scheme != "https" {
+		return fmt.Errorf("must use http or https")
+	}
+	if parsed.User != nil {
+		return fmt.Errorf("must not include userinfo")
+	}
+	if parsed.RawQuery != "" || parsed.Fragment != "" {
+		return fmt.Errorf("must not include query or fragment")
+	}
+	return nil
+}
+
 func validateDistributorBatchNotify(cfg DistributorBatchNotifyConfig) error {
 	if !cfg.Enabled {
 		return nil