feat: allow ipv6 services

Author: borislitv

internal/servicecheck/servicecheck.go

@@ -143,7 +143,7 @@ func (c *Checker) APIServerDirect(ctx context.Context) string {
 		return skippedStr
 	}
 
-	apiurl := fmt.Sprintf("https://%s:%s/version", c.KubernetesServiceHost, c.KubernetesServicePort)
+	apiurl := fmt.Sprintf("https://%s:%s/version", formatIPForURL(c.KubernetesServiceHost), c.KubernetesServicePort)
 
 	return c.doRequest(ctx, apiurl, false)
 }
@@ -154,7 +154,7 @@ func (c *Checker) APIServerDNS(ctx context.Context) string {
 		return skippedStr
 	}
 
-	apiurl := fmt.Sprintf("https://%s:%s/version", c.KubernetesServiceDNS, c.KubernetesServicePort)
+	apiurl := fmt.Sprintf("https://%s:%s/version", formatIPForURL(c.KubernetesServiceDNS), c.KubernetesServicePort)
 
 	return c.doRequest(ctx, apiurl, false)
 }
@@ -188,10 +188,21 @@ func (c *Checker) measure(ctx context.Context, wg *sync.WaitGroup, res *sync.Map
 	res.Store(requestType, check(ctx))
 }
 
+// formatIPForURL formats an IP address for use in a URL
+// If the IP is an IPv6 address, it encloses it in square brackets [...]
+func formatIPForURL(ip string) string {
+	if parsedIP := net.ParseIP(ip); parsedIP != nil && parsedIP.To4() == nil {
+		return "[" + ip + "]"
+	}
+	return ip
+}
+
 func podIPtoURL(podIP string, useTLS bool) string {
+	formattedIP := formatIPForURL(podIP)
+
 	if useTLS {
-		return "https://" + podIP + ":8443/alwayshappy"
+		return "https://" + formattedIP + ":8443/alwayshappy"
 	}
 
-	return "http://" + podIP + ":8080/alwayshappy"
+	return "http://" + formattedIP + ":8080/alwayshappy"
 }