minikube update-context: Fix nil pointer dereference

go.mod

@@ -72,7 +72,6 @@ require (
 	github.com/zchee/go-vmnet v0.0.0-20161021174912-97ebf9174097
 	golang.org/x/build v0.0.0-20190927031335-2835ba2e683f
 	golang.org/x/crypto v0.0.0-20200510223506-06a226fb4e37
-	golang.org/x/exp v0.0.0-20200224162631-6cc2880d07d6 // indirect
 	golang.org/x/oauth2 v0.0.0-20200107190931-bf48bf16ab8d
 	golang.org/x/sync v0.0.0-20200317015054-43a5402ce75a
 	golang.org/x/sys v0.0.0-20200523222454-059865788121

pkg/minikube/kubeconfig/kubeconfig.go

@@ -123,8 +123,8 @@ func UpdateEndpoint(contextName string, hostname string, port int, confpath stri
 
 	address := "https://" + hostname + ":" + strconv.Itoa(port)
 
-	// if the kubeconfig is missed, create new one
-	if len(cfg.Clusters) == 0 {
+	// if the cluster setting is missed in the kubeconfig, create new one
+	if _, ok := cfg.Clusters[contextName]; !ok {
 		lp := localpath.Profile(contextName)
 		gp := localpath.MiniPath()
 		kcs := &Settings{
@@ -139,8 +139,10 @@ func UpdateEndpoint(contextName string, hostname string, port int, confpath stri
 		if err != nil {
 			return false, errors.Wrap(err, "populating kubeconfig")
 		}
+	} else {
+		cfg.Clusters[contextName].Server = address
 	}
-	cfg.Clusters[contextName].Server = address
+
 	err = writeToFile(cfg, confpath)
 	if err != nil {
 		return false, errors.Wrap(err, "write")

pkg/minikube/kubeconfig/kubeconfig_test.go

@@ -25,6 +25,7 @@ import (
 
 	"k8s.io/client-go/tools/clientcmd/api"
 	"k8s.io/minikube/pkg/minikube/constants"
+	"k8s.io/minikube/pkg/minikube/localpath"
 
 	"k8s.io/client-go/tools/clientcmd"
 )
@@ -51,6 +52,40 @@ users:
     client-key: /home/la-croix/apiserver.key
 `)
 
+var kubeConfigWithoutHTTPSUpdated = []byte(`
+apiVersion: v1
+clusters:
+- cluster:
+    certificate-authority: /home/la-croix/apiserver.crt
+    server: 192.168.1.1:8080
+  name: la-croix
+- cluster:
+    certificate-authority: /home/la-croix/.minikube/ca.crt
+    server: https://192.168.10.100:8080
+  name: minikube
+contexts:
+- context:
+    cluster: la-croix
+    user: la-croix
+  name: la-croix
+- context:
+    cluster: minikube
+    user: minikube
+  name: minikube
+current-context: minikube
+kind: Config
+preferences: {}
+users:
+- name: la-croix
+  user:
+    client-certificate: /home/la-croix/apiserver.crt
+    client-key: /home/la-croix/apiserver.key
+- name: minikube
+  user:
+    client-certificate: /home/la-croix/.minikube/profiles/minikube/client.crt
+    client-key: /home/la-croix/.minikube/profiles/minikube/client.key
+`)
+
 var kubeConfig192 = []byte(`
 apiVersion: v1
 clusters:
@@ -117,6 +152,37 @@ users:
     client-key: /home/la-croix/apiserver.key
 `)
 
+var kubeConfigNoClusters = []byte(`
+apiVersion: v1
+clusters:
+contexts:
+kind: Config
+preferences: {}
+users:
+`)
+
+var kubeConfigNoClustersUpdated = []byte(`
+apiVersion: v1
+clusters:
+- cluster:
+    certificate-authority: /home/la-croix/.minikube/ca.crt
+    server: https://192.168.10.100:8080
+  name: minikube
+contexts:
+- context:
+    cluster: minikube
+    user: minikube
+  name: minikube
+current-context: minikube
+kind: Config
+preferences: {}
+users:
+- name: minikube
+  user:
+    client-certificate: /home/la-croix/.minikube/profiles/minikube/client.crt
+    client-key: /home/la-croix/.minikube/profiles/minikube/client.key
+`)
+
 func TestUpdate(t *testing.T) {
 	setupCfg := &Settings{
 		ClusterName:          "test",
@@ -300,8 +366,8 @@ func TestUpdateIP(t *testing.T) {
 			hostname:    "192.168.10.100",
 			port:        8080,
 			existing:    kubeConfigWithoutHTTPS,
-			err:         true,
-			expCfg:      kubeConfigWithoutHTTPS,
+			status:      true,
+			expCfg:      kubeConfigWithoutHTTPSUpdated,
 		},
 		{
 			description: "same IP",
@@ -326,8 +392,20 @@ func TestUpdateIP(t *testing.T) {
 			status:      true,
 			expCfg:      kubeConfigLocalhost12345,
 		},
+		{
+			description: "no clusters",
+			hostname:    "192.168.10.100",
+			port:        8080,
+			existing:    kubeConfigNoClusters,
+			status:      true,
+			expCfg:      kubeConfigNoClustersUpdated,
+		},
 	}
+
+	os.Setenv(localpath.MinikubeHome, "/home/la-croix")
+
 	for _, test := range tests {
+		test := test
 		t.Run(test.description, func(t *testing.T) {
 			t.Parallel()
 			configFilename := tempFile(t, test.existing)
@@ -342,6 +420,18 @@ func TestUpdateIP(t *testing.T) {
 			if test.status != statusActual {
 				t.Errorf("Expected status %t, but got %t", test.status, statusActual)
 			}
+
+			actual, err := readOrNew(configFilename)
+			if err != nil {
+				t.Fatal(err)
+			}
+			expected, err := decode(test.expCfg)
+			if err != nil {
+				t.Fatal(err)
+			}
+			if !configEquals(actual, expected) {
+				t.Fatal("configs did not match")
+			}
 		})
 
 	}

test/integration/functional_test.go

@@ -1007,14 +1007,86 @@ func validateCertSync(ctx context.Context, t *testing.T, profile string) {
 func validateUpdateContextCmd(ctx context.Context, t *testing.T, profile string) {
 	defer PostMortemLogs(t, profile)
 
-	rr, err := Run(t, exec.CommandContext(ctx, Target(), "-p", profile, "update-context", "--alsologtostderr", "-v=2"))
-	if err != nil {
-		t.Errorf("failed to run minikube update-context: args %q: %v", rr.Command(), err)
+	tests := []struct {
+		name       string
+		kubeconfig []byte
+		want       []byte
+	}{
+		{
+			name:       "no changes",
+			kubeconfig: nil,
+			want:       []byte("No changes"),
+		},
+		{
+			name: "no minikube cluster",
+			kubeconfig: []byte(`
+apiVersion: v1
+clusters:
+- cluster:
+    certificate-authority: /home/la-croix/apiserver.crt
+    server: 192.168.1.1:8080
+  name: la-croix
+contexts:
+- context:
+    cluster: la-croix
+    user: la-croix
+  name: la-croix
+current-context: la-croix
+kind: Config
+preferences: {}
+users:
+- name: la-croix
+  user:
+    client-certificate: /home/la-croix/apiserver.crt
+    client-key: /home/la-croix/apiserver.key
+`),
+			want: []byte("context has been updated"),
+		},
+		{
+			name: "no clusters",
+			kubeconfig: []byte(`
+apiVersion: v1
+clusters:
+contexts:
+kind: Config
+preferences: {}
+users:
+`),
+			want: []byte("context has been updated"),
+		},
 	}
 
-	want := []byte("No changes")
-	if !bytes.Contains(rr.Stdout.Bytes(), want) {
-		t.Errorf("update-context: got=%q, want=*%q*", rr.Stdout.Bytes(), want)
+	for _, tc := range tests {
+		tc := tc
+		t.Run(tc.name, func(t *testing.T) {
+			t.Parallel()
+			c := exec.CommandContext(ctx, Target(), "-p", profile, "update-context", "--alsologtostderr", "-v=2")
+			if tc.kubeconfig != nil {
+				tf, err := ioutil.TempFile("", "kubeconfig")
+				if err != nil {
+					t.Fatal(err)
+				}
+
+				if err := ioutil.WriteFile(tf.Name(), tc.kubeconfig, 0644); err != nil {
+					t.Fatal(err)
+				}
+
+				t.Cleanup(func() {
+					os.Remove(tf.Name())
+				})
+
+				c.Env = append(os.Environ(), fmt.Sprintf("KUBECONFIG=%s", tf.Name()))
+			}
+
+			rr, err := Run(t, c)
+			if err != nil {
+				t.Errorf("failed to run minikube update-context: args %q: %v", rr.Command(), err)
+			}
+
+			if !bytes.Contains(rr.Stdout.Bytes(), tc.want) {
+				t.Errorf("update-context: got=%q, want=*%q*", rr.Stdout.Bytes(), tc.want)
+			}
+		})
 	}
 }