From 7fb4a2be41c9b45778c6562e36adc57b78d77c55 Mon Sep 17 00:00:00 2001
From: Alexander Kanevskiy <alexander.kanevskiy@intel.com>
Date: Tue, 3 Sep 2019 15:55:58 +0300
Subject: [PATCH] kubeadm: Form correct URL for IPv6 in HTTPProxy check

Force correct syntax on host/port in URL of HTTPProxy check
if the host argument is a raw IPv6 address string
---
 cmd/kubeadm/app/preflight/checks.go      |  7 +++++--
 cmd/kubeadm/app/preflight/checks_test.go | 16 ++++++++++++++++
 2 files changed, 21 insertions(+), 2 deletions(-)

diff --git a/cmd/kubeadm/app/preflight/checks.go b/cmd/kubeadm/app/preflight/checks.go
index adc0b694780..21e2694d35f 100644
--- a/cmd/kubeadm/app/preflight/checks.go
+++ b/cmd/kubeadm/app/preflight/checks.go
@@ -431,9 +431,12 @@ func (hst HTTPProxyCheck) Name() string {
 // Check validates http connectivity type, direct or via proxy.
 func (hst HTTPProxyCheck) Check() (warnings, errorList []error) {
 	klog.V(1).Infoln("validating if the connectivity type is via proxy or direct")
-	u := (&url.URL{Scheme: hst.Proto, Host: hst.Host}).String()
+	u := &url.URL{Scheme: hst.Proto, Host: hst.Host}
+	if utilsnet.IsIPv6String(hst.Host) {
+		u.Host = net.JoinHostPort(hst.Host, "1234")
+	}
 
-	req, err := http.NewRequest("GET", u, nil)
+	req, err := http.NewRequest("GET", u.String(), nil)
 	if err != nil {
 		return nil, []error{err}
 	}
diff --git a/cmd/kubeadm/app/preflight/checks_test.go b/cmd/kubeadm/app/preflight/checks_test.go
index 60945e08742..5adea3ee433 100644
--- a/cmd/kubeadm/app/preflight/checks_test.go
+++ b/cmd/kubeadm/app/preflight/checks_test.go
@@ -590,6 +590,22 @@ func TestHTTPProxyCheck(t *testing.T) {
 			}, // Expected to go via proxy, range is not in 2001:db8::/48
 			expectWarnings: true,
 		},
+		{
+			name: "IPv6 direct access, no brackets",
+			check: HTTPProxyCheck{
+				Proto: "https",
+				Host:  "2001:db8::1:15",
+			}, // Expected to be accessed directly, part of 2001:db8::/48 in NO_PROXY
+			expectWarnings: false,
+		},
+		{
+			name: "IPv6 via proxy, no brackets",
+			check: HTTPProxyCheck{
+				Proto: "https",
+				Host:  "2001:db8:1::1:15",
+			}, // Expected to go via proxy, range is not in 2001:db8::/48
+			expectWarnings: true,
+		},
 	}
 
 	// Save current content of *_proxy and *_PROXY variables.