test: add unit test, make default not static

pkg/api/defaults-kubelet.go

@@ -25,7 +25,6 @@ func (cs *ContainerService) setKubeletConfig() {
 		"--cgroups-per-qos":             "true",
 		"--kubeconfig":                  "/var/lib/kubelet/kubeconfig",
 		"--keep-terminated-pod-volumes": "false",
-		"--protect-kernel-defaults":     "true",
 	}
 
 	// Start with copy of Linux config
@@ -80,6 +79,7 @@ func (cs *ContainerService) setKubeletConfig() {
 		"--image-pull-progress-deadline":      "30m",
 		"--enforce-node-allocatable":          "pods",
 		"--streaming-connection-idle-timeout": "5m",
+		"--protect-kernel-defaults":           "true",
 	}
 
 	// Set --non-masquerade-cidr if ip-masq-agent is disabled on AKS

pkg/api/defaults-kubelet_test.go

@@ -361,6 +361,31 @@ func TestEnforceNodeAllocatable(t *testing.T) {
 	}
 }
 
+func TestProtectKernelDefaults(t *testing.T) {
+	// Validate default
+	cs := CreateMockContainerService("testcluster", "1.12.7", 3, 2, false)
+	cs.setKubeletConfig()
+	k := cs.Properties.OrchestratorProfile.KubernetesConfig.KubeletConfig
+	if k["--protect-kernel-defaults"] != "true" {
+		t.Fatalf("got unexpected '--protect-kernel-defaults' kubelet config value %s, the expected value is %s",
+			k["--protect-kernel-defaults"], "pods")
+	}
+
+	// Validate that --protect-kernel-defaults is overridable
+	cs = CreateMockContainerService("testcluster", "1.10.13", 3, 2, false)
+	cs.Properties.OrchestratorProfile.KubernetesConfig = &KubernetesConfig{
+		KubeletConfig: map[string]string{
+			"--protect-kernel-defaults": "false",
+		},
+	}
+	cs.setKubeletConfig()
+	k = cs.Properties.OrchestratorProfile.KubernetesConfig.KubeletConfig
+	if k["--protect-kernel-defaults"] != "false" {
+		t.Fatalf("got unexpected '--protect-kernel-defaults' kubelet config value %s, the expected value is %s",
+			k["--protect-kernel-defaults"], "false")
+	}
+}
+
 func TestStaticWindowsConfig(t *testing.T) {
 	cs := CreateMockContainerService("testcluster", defaultTestClusterVer, 3, 1, false)
 	p := GetK8sDefaultProperties(true)