Add a preflight check that the control-plane node has at least 2GB RAM

Signed-off-by: Xianglin Gao <[email protected]>

Author: Xianglin Gao

cmd/kubeadm/app/constants/constants.go

@@ -350,6 +350,9 @@ const (
 	// ControlPlaneNumCPU is the number of CPUs required on control-plane
 	ControlPlaneNumCPU = 2
 
+	// ControlPlaneMem is the number of megabytes of memory required on the control-plane
+	ControlPlaneMem = 2 * 1024
+
 	// KubeadmCertsSecret specifies in what Secret in the kube-system namespace the certificates should be stored
 	KubeadmCertsSecret = "kubeadm-certs"
 

cmd/kubeadm/app/preflight/BUILD

@@ -28,6 +28,7 @@ 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

@@ -35,6 +35,7 @@ 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"
@@ -869,6 +870,25 @@ func (ncc NumCPUCheck) Check() (warnings, errorList []error) {
 	return warnings, errorList
 }
 
+// MemCheck checks if the number of megabytes of memory is not less than required
+type MemCheck struct {
+	Mem uint64
+}
+
+// Name returns the label for memory
+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.
@@ -884,6 +904,7 @@ func RunInitNodeChecks(execer utilsexec.Interface, cfg *kubeadmapi.InitConfigura
 	manifestsDir := filepath.Join(kubeadmconstants.KubernetesDir, kubeadmconstants.ManifestsSubDirName)
 	checks := []Checker{
 		NumCPUCheck{NumCPU: kubeadmconstants.ControlPlaneNumCPU},
+		MemCheck{Mem: kubeadmconstants.ControlPlaneMem},
 		KubernetesVersionCheck{KubernetesVersion: cfg.KubernetesVersion, KubeadmVersion: kubeadmversion.Get().GitVersion},
 		FirewalldCheck{ports: []int{int(cfg.LocalAPIEndpoint.BindPort), kubeadmconstants.KubeletPort}},
 		PortOpenCheck{port: int(cfg.LocalAPIEndpoint.BindPort)},

go.mod

@@ -79,6 +79,7 @@ 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

@@ -376,6 +376,8 @@ 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=