add test case for kubeadm memory check

Signed-off-by: Xianglin Gao <xianglin.gxl@alibaba-inc.com>

cmd/kubeadm/app/constants/constants.go

@@ -351,7 +351,8 @@ const (
 	ControlPlaneNumCPU = 2
 
 	// ControlPlaneMem is the number of megabytes of memory required on the control-plane
-	ControlPlaneMem = 2 * 1024
+	// Below that amount of RAM running a stable control plane would be difficult.
+	ControlPlaneMem = 1700
 
 	// KubeadmCertsSecret specifies in what Secret in the kube-system namespace the certificates should be stored
 	KubeadmCertsSecret = "kubeadm-certs"

cmd/kubeadm/app/preflight/BUILD

@@ -28,7 +28,6 @@ go_library(
         "//staging/src/k8s.io/apimachinery/pkg/util/version:go_default_library",
         "//staging/src/k8s.io/component-base/version:go_default_library",
         "//vendor/github.com/PuerkitoBio/purell:go_default_library",
-        "//vendor/github.com/pbnjay/memory:go_default_library",
         "//vendor/github.com/pkg/errors:go_default_library",
         "//vendor/k8s.io/klog/v2:go_default_library",
         "//vendor/k8s.io/system-validators/validators:go_default_library",

cmd/kubeadm/app/preflight/checks.go

@@ -35,7 +35,6 @@ import (
 	"time"
 
 	"github.com/PuerkitoBio/purell"
-	"github.com/pbnjay/memory"
 	"github.com/pkg/errors"
 	netutil "k8s.io/apimachinery/pkg/util/net"
 	"k8s.io/apimachinery/pkg/util/sets"
@@ -880,15 +879,6 @@ func (MemCheck) Name() string {
 	return "Mem"
 }
 
-// Check number of memory required by kubeadm
-func (mc MemCheck) Check() (warnings, errorList []error) {
-	actual := memory.TotalMemory() / 1024 / 1024 // TotalMemory returns bytes; convert to MB
-	if actual < mc.Mem {
-		errorList = append(errorList, errors.Errorf("the system RAM (%d MB) is less than the minimum %d MB", actual, mc.Mem))
-	}
-	return warnings, errorList
-}
-
 // RunInitNodeChecks executes all individual, applicable to control-plane node checks.
 // The boolean flag 'isSecondaryControlPlane' controls whether we are running checks in a --join-control-plane scenario.
 // The boolean flag 'downloadCerts' controls whether we should skip checks on certificates because we are downloading them.
@@ -904,6 +894,8 @@ func RunInitNodeChecks(execer utilsexec.Interface, cfg *kubeadmapi.InitConfigura
 	manifestsDir := filepath.Join(kubeadmconstants.KubernetesDir, kubeadmconstants.ManifestsSubDirName)
 	checks := []Checker{
 		NumCPUCheck{NumCPU: kubeadmconstants.ControlPlaneNumCPU},
+		// Linux only
+		// TODO: support other OS, if control-plane is supported on it.
 		MemCheck{Mem: kubeadmconstants.ControlPlaneMem},
 		KubernetesVersionCheck{KubernetesVersion: cfg.KubernetesVersion, KubeadmVersion: kubeadmversion.Get().GitVersion},
 		FirewalldCheck{ports: []int{int(cfg.LocalAPIEndpoint.BindPort), kubeadmconstants.KubeletPort}},

cmd/kubeadm/app/preflight/checks_darwin.go

@@ -25,3 +25,9 @@ package preflight
 func (idsc IsDockerSystemdCheck) Check() (warnings, errorList []error) {
 	return nil, nil
 }
+
+// Check number of memory required by kubeadm
+// No-op for Darwin (MacOS).
+func (mc MemCheck) Check() (warnings, errorList []error) {
+	return nil, nil
+}

cmd/kubeadm/app/preflight/checks_linux.go

@@ -19,6 +19,8 @@ limitations under the License.
 package preflight
 
 import (
+	"syscall"
+
 	"github.com/pkg/errors"
 	kubeadmutil "k8s.io/kubernetes/cmd/kubeadm/app/util"
 	"k8s.io/utils/exec"
@@ -40,3 +42,19 @@ func (idsc IsDockerSystemdCheck) Check() (warnings, errorList []error) {
 	}
 	return nil, nil
 }
+
+// Check number of memory required by kubeadm
+func (mc MemCheck) Check() (warnings, errorList []error) {
+	info := syscall.Sysinfo_t{}
+	err := syscall.Sysinfo(&info)
+	if err != nil {
+		errorList = append(errorList, errors.Wrapf(err, "failed to get system info"))
+	}
+
+	// Totalram returns bytes; convert to MB
+	actual := uint64(info.Totalram) / 1024 / 1024
+	if actual < mc.Mem {
+		errorList = append(errorList, errors.Errorf("the system RAM (%d MB) is less than the minimum %d MB", actual, mc.Mem))
+	}
+	return warnings, errorList
+}

cmd/kubeadm/app/preflight/checks_test.go

@@ -20,6 +20,7 @@ import (
 	"bytes"
 	"fmt"
 	"io/ioutil"
+	"runtime"
 	"strings"
 	"testing"
 
@@ -849,3 +850,29 @@ func TestNumCPUCheck(t *testing.T) {
 		})
 	}
 }
+
+func TestMemCheck(t *testing.T) {
+	// skip this test, if OS in not Linux, since it will ONLY pass on Linux.
+	if runtime.GOOS != "linux" {
+		t.Skip("unsupported OS for memory check test ")
+	}
+
+	var tests = []struct {
+		minimum        uint64
+		expectedErrors int
+	}{
+		{0, 0},
+		{9999999999999999, 1},
+	}
+
+	for _, rt := range tests {
+		t.Run(fmt.Sprintf("MemoryCheck{%d}", rt.minimum), func(t *testing.T) {
+			warnings, errors := MemCheck{Mem: rt.minimum}.Check()
+			if len(warnings) > 0 {
+				t.Errorf("expected 0 warnings but got %d: %q", len(warnings), warnings)
+			} else if len(errors) != rt.expectedErrors {
+				t.Errorf("expected %d error(s) but got %d: %q", rt.expectedErrors, len(errors), errors)
+			}
+		})
+	}
+}

cmd/kubeadm/app/preflight/checks_windows.go

@@ -54,3 +54,9 @@ func (ipuc IsPrivilegedUserCheck) Check() (warnings, errorList []error) {
 func (idsc IsDockerSystemdCheck) Check() (warnings, errorList []error) {
 	return nil, nil
 }
+
+// Check number of memory required by kubeadm
+// No-op for Windows.
+func (mc MemCheck) Check() (warnings, errorList []error) {
+	return nil, nil
+}

go.mod

@@ -79,7 +79,6 @@ require (
 	github.com/opencontainers/go-digest v1.0.0-rc1
 	github.com/opencontainers/runc v1.0.0-rc91.0.20200707015106-819fcc687efb
 	github.com/opencontainers/selinux v1.5.2
-	github.com/pbnjay/memory v0.0.0-20190104145345-974d429e7ae4
 	github.com/pkg/errors v0.9.1
 	github.com/pmezard/go-difflib v1.0.0
 	github.com/prometheus/client_golang v1.7.1

go.sum

@@ -376,8 +376,6 @@ github.com/opencontainers/runtime-spec v1.0.3-0.20200520003142-237cc4f519e2 h1:9
 github.com/opencontainers/runtime-spec v1.0.3-0.20200520003142-237cc4f519e2/go.mod h1:jwyrGlmzljRJv/Fgzds9SsS/C5hL+LL3ko9hs6T5lQ0=
 github.com/opencontainers/selinux v1.5.2 h1:F6DgIsjgBIcDksLW4D5RG9bXok6oqZ3nvMwj4ZoFu/Q=
 github.com/opencontainers/selinux v1.5.2/go.mod h1:yTcKuYAh6R95iDpefGLQaPaRwJFwyzAJufJyiTt7s0g=
-github.com/pbnjay/memory v0.0.0-20190104145345-974d429e7ae4 h1:MfIUBZ1bz7TgvQLVa/yPJZOGeKEgs6eTKUjz3zB4B+U=
-github.com/pbnjay/memory v0.0.0-20190104145345-974d429e7ae4/go.mod h1:RMU2gJXhratVxBDTFeOdNhd540tG57lt9FIUV0YLvIQ=
 github.com/pelletier/go-toml v1.2.0 h1:T5zMGML61Wp+FlcbWjRDT7yAxhJNAiPPLOFECq181zc=
 github.com/pelletier/go-toml v1.2.0/go.mod h1:5z9KED0ma1S8pY6P1sdut58dfprrGBbd/94hg7ilaic=
 github.com/peterbourgon/diskv v2.0.1+incompatible h1:UBdAOUP5p4RWqPBg048CAvpKN+vxiaj6gdUUzhl4XmI=