diff --git a/cmd/kubeadm/app/phases/addons/proxy/proxy.go b/cmd/kubeadm/app/phases/addons/proxy/proxy.go
index 6c9fdd28492..35f9d7335e1 100644
--- a/cmd/kubeadm/app/phases/addons/proxy/proxy.go
+++ b/cmd/kubeadm/app/phases/addons/proxy/proxy.go
@@ -259,7 +259,7 @@ func createKubeProxyAddon(cfg *kubeadmapi.ClusterConfiguration, client clientset
 	}
 	// Propagate the http/https proxy host environment variables to the container
 	env := &kubeproxyDaemonSet.Spec.Template.Spec.Containers[0].Env
-	*env = append(*env, kubeadmutil.MergeKubeadmEnvVars(kubeadmutil.GetProxyEnvVars())...)
+	*env = append(*env, kubeadmutil.MergeKubeadmEnvVars(kubeadmutil.GetProxyEnvVars(nil))...)
 
 	// Create the DaemonSet for kube-proxy or update it in case it already exists
 	return []byte(""), apiclient.CreateOrUpdateDaemonSet(client, kubeproxyDaemonSet)
diff --git a/cmd/kubeadm/app/phases/controlplane/manifests.go b/cmd/kubeadm/app/phases/controlplane/manifests.go
index 11b93e083db..2c2b7f8b35e 100644
--- a/cmd/kubeadm/app/phases/controlplane/manifests.go
+++ b/cmd/kubeadm/app/phases/controlplane/manifests.go
@@ -52,7 +52,7 @@ func GetStaticPodSpecs(cfg *kubeadmapi.ClusterConfiguration, endpoint *kubeadmap
 	// Get the required hostpath mounts
 	mounts := getHostPathVolumesForTheControlPlane(cfg)
 	if proxyEnvs == nil {
-		proxyEnvs = kubeadmutil.GetProxyEnvVars()
+		proxyEnvs = kubeadmutil.GetProxyEnvVars(nil)
 	}
 	componentHealthCheckTimeout := kubeadmapi.GetActiveTimeouts().ControlPlaneComponentHealthCheck
 
diff --git a/cmd/kubeadm/app/util/env.go b/cmd/kubeadm/app/util/env.go
index 5534b1d212a..d34a9a4ce2a 100644
--- a/cmd/kubeadm/app/util/env.go
+++ b/cmd/kubeadm/app/util/env.go
@@ -18,6 +18,7 @@ package util
 
 import (
 	"os"
+	"sort"
 	"strings"
 
 	v1 "k8s.io/api/core/v1"
@@ -25,13 +26,17 @@ import (
 	kubeadmapi "k8s.io/kubernetes/cmd/kubeadm/app/apis/kubeadm"
 )
 
-// GetProxyEnvVars builds a list of environment variables in order to use the right proxy
-func GetProxyEnvVars() []kubeadmapi.EnvVar {
+// GetProxyEnvVars builds a list of environment variables in order to use the right proxy.
+// Passing nil for environment will make the function use the OS environment.
+func GetProxyEnvVars(environment []string) []kubeadmapi.EnvVar {
 	envs := []kubeadmapi.EnvVar{}
-	for _, env := range os.Environ() {
+	if environment == nil {
+		environment = os.Environ()
+	}
+	for _, env := range environment {
 		pos := strings.Index(env, "=")
 		if pos == -1 {
-			// malformed environment variable, skip it.
+			// Malformed environment variable, skip it.
 			continue
 		}
 		name := env[:pos]
@@ -59,5 +64,8 @@ func MergeKubeadmEnvVars(envList ...[]kubeadmapi.EnvVar) []v1.EnvVar {
 	for _, v := range m {
 		merged = append(merged, v)
 	}
+	sort.Slice(merged, func(i, j int) bool {
+		return merged[i].Name < merged[j].Name
+	})
 	return merged
 }
diff --git a/cmd/kubeadm/app/util/env_test.go b/cmd/kubeadm/app/util/env_test.go
index ad70a4e8584..7442edec49e 100644
--- a/cmd/kubeadm/app/util/env_test.go
+++ b/cmd/kubeadm/app/util/env_test.go
@@ -17,10 +17,9 @@ limitations under the License.
 package util
 
 import (
+	"reflect"
 	"testing"
 
-	"github.com/stretchr/testify/assert"
-
 	v1 "k8s.io/api/core/v1"
 
 	kubeadmapi "k8s.io/kubernetes/cmd/kubeadm/app/apis/kubeadm"
@@ -40,10 +39,10 @@ func TestMergeKubeadmEnvVars(t *testing.T) {
 			name: "normal case without duplicated env",
 			proxyEnv: []kubeadmapi.EnvVar{
 				{
-					EnvVar: v1.EnvVar{Name: "Foo1", Value: "Bar1"},
+					EnvVar: v1.EnvVar{Name: "Foo2", Value: "Bar2"},
 				},
 				{
-					EnvVar: v1.EnvVar{Name: "Foo2", Value: "Bar2"},
+					EnvVar: v1.EnvVar{Name: "Foo1", Value: "Bar1"},
 				},
 			},
 			extraEnv: []kubeadmapi.EnvVar{
@@ -82,9 +81,57 @@ func TestMergeKubeadmEnvVars(t *testing.T) {
 	for _, test := range tests {
 		t.Run(test.name, func(t *testing.T) {
 			envs := MergeKubeadmEnvVars(test.proxyEnv, test.extraEnv)
-			if !assert.ElementsMatch(t, envs, test.mergedEnv) {
+			if !reflect.DeepEqual(envs, test.mergedEnv) {
 				t.Errorf("expected env: %v, got: %v", test.mergedEnv, envs)
 			}
 		})
 	}
 }
+
+func TestGetProxyEnvVars(t *testing.T) {
+	var tests = []struct {
+		name        string
+		environment []string
+		expected    []kubeadmapi.EnvVar
+	}{
+		{
+			name: "environment with lowercase proxy vars",
+			environment: []string{
+				"http_proxy=p1",
+				"foo1=bar1",
+				"https_proxy=p2",
+				"foo2=bar2",
+				"no_proxy=p3",
+			},
+			expected: []kubeadmapi.EnvVar{
+				{EnvVar: v1.EnvVar{Name: "http_proxy", Value: "p1"}},
+				{EnvVar: v1.EnvVar{Name: "https_proxy", Value: "p2"}},
+				{EnvVar: v1.EnvVar{Name: "no_proxy", Value: "p3"}},
+			},
+		},
+		{
+			name: "environment with uppercase proxy vars",
+			environment: []string{
+				"HTTP_PROXY=p1",
+				"foo1=bar1",
+				"HTTPS_PROXY=p2",
+				"foo2=bar2",
+				"NO_PROXY=p3",
+			},
+			expected: []kubeadmapi.EnvVar{
+				{EnvVar: v1.EnvVar{Name: "HTTP_PROXY", Value: "p1"}},
+				{EnvVar: v1.EnvVar{Name: "HTTPS_PROXY", Value: "p2"}},
+				{EnvVar: v1.EnvVar{Name: "NO_PROXY", Value: "p3"}},
+			},
+		},
+	}
+
+	for _, test := range tests {
+		t.Run(test.name, func(t *testing.T) {
+			envs := GetProxyEnvVars(test.environment)
+			if !reflect.DeepEqual(envs, test.expected) {
+				t.Errorf("expected env: %v, got: %v", test.expected, envs)
+			}
+		})
+	}
+}