Merge pull request #54539 from jamiehannaford/add-ha-feature-gate

Automatic merge from submit-queue (batch tested with PRs 54593, 54607, 54539, 54105). If you want to cherry-pick this change to another branch, please follow the instructions <a href="https://github.com/kubernetes/community/blob/master/contributors/devel/cherry-picks.md">here</a>.

Add HA feature gate and minVersion validation

**What this PR does / why we need it**:

As we add more feature gates, there might be occasions where a feature is only available on newer releases of K8s. If a user makes a mistake, we should notify them as soon as possible in the init procedure and not them go down the path of hard-to-debug component issues.

Specifically with HA, we ideally need the new `TaintNodesByCondition` (added in v1.8.0 but working in v1.9.0).

**Which issue this PR fixes:**

kubernetes/kubeadm#261
kubernetes/kubeadm#277

**Release note**:
```release-note
Feature gates now check minimum versions
```

/cc @kubernetes/sig-cluster-lifecycle-pr-reviews @luxas @timothysc

cmd/kubeadm/app/cmd/init.go

@@ -231,6 +231,10 @@ func NewInit(cfgPath string, cfg *kubeadmapi.MasterConfiguration, skipPreFlight,
 		return nil, err
 	}
 
+	if err := features.ValidateVersion(features.InitFeatureGates, cfg.FeatureGates, cfg.KubernetesVersion); err != nil {
+		return nil, err
+	}
+
 	fmt.Printf("[init] Using Kubernetes version: %s\n", cfg.KubernetesVersion)
 	fmt.Printf("[init] Using Authorization modes: %v\n", cfg.AuthorizationModes)
 

cmd/kubeadm/app/features/BUILD

@@ -10,7 +10,10 @@ go_library(
     name = "go_default_library",
     srcs = ["features.go"],
     importpath = "k8s.io/kubernetes/cmd/kubeadm/app/features",
-    deps = ["//vendor/k8s.io/apiserver/pkg/util/feature:go_default_library"],
+    deps = [
+        "//pkg/util/version:go_default_library",
+        "//vendor/k8s.io/apiserver/pkg/util/feature:go_default_library",
+    ],
 )
 
 filegroup(

cmd/kubeadm/app/features/features.go

@@ -23,21 +23,61 @@ import (
 	"strings"
 
 	utilfeature "k8s.io/apiserver/pkg/util/feature"
+	"k8s.io/kubernetes/pkg/util/version"
 )
 
 const (
+	// HighAvailability is alpha in v1.9
+	HighAvailability = "HighAvailability"
+
 	// SelfHosting is beta in v1.8
-	SelfHosting utilfeature.Feature = "SelfHosting"
+	SelfHosting = "SelfHosting"
 
 	// StoreCertsInSecrets is alpha in v1.8
-	StoreCertsInSecrets utilfeature.Feature = "StoreCertsInSecrets"
+	StoreCertsInSecrets = "StoreCertsInSecrets"
 )
 
+var v190 = version.MustParseSemantic("v1.9.0")
+
+// InitFeatureGates are the default feature gates for the init command
+var InitFeatureGates = FeatureList{
+	SelfHosting:         {FeatureSpec: utilfeature.FeatureSpec{Default: false, PreRelease: utilfeature.Beta}},
+	StoreCertsInSecrets: {FeatureSpec: utilfeature.FeatureSpec{Default: false, PreRelease: utilfeature.Alpha}},
+	HighAvailability:    {FeatureSpec: utilfeature.FeatureSpec{Default: false, PreRelease: utilfeature.Alpha}, MinimumVersion: v190},
+}
+
+// Feature represents a feature being gated
+type Feature struct {
+	utilfeature.FeatureSpec
+	MinimumVersion *version.Version
+}
+
 // FeatureList represents a list of feature gates
-type FeatureList map[utilfeature.Feature]utilfeature.FeatureSpec
+type FeatureList map[string]Feature
+
+// ValidateVersion ensures that a feature gate list is compatible with the chosen kubernetes version
+func ValidateVersion(allFeatures FeatureList, requestedFeatures map[string]bool, requestedVersion string) error {
+	if requestedVersion == "" {
+		return nil
+	}
+	parsedExpVersion, err := version.ParseSemantic(requestedVersion)
+	if err != nil {
+		return fmt.Errorf("Error parsing version %s: %v", requestedVersion, err)
+	}
+	for k := range requestedFeatures {
+		if minVersion := allFeatures[k].MinimumVersion; minVersion != nil {
+			if !parsedExpVersion.AtLeast(minVersion) {
+				return fmt.Errorf(
+					"the requested kubernetes version (%s) is incompatible with the %s feature gate, which needs %s as a minimum",
+					requestedVersion, k, minVersion)
+			}
+		}
+	}
+	return nil
+}
 
 // Enabled indicates whether a feature name has been enabled
-func Enabled(featureList map[string]bool, featureName utilfeature.Feature) bool {
+func Enabled(featureList map[string]bool, featureName string) bool {
 	return featureList[string(featureName)]
 }
 
@@ -61,12 +101,6 @@ func Keys(featureList FeatureList) []string {
 	return list
 }
 
-// InitFeatureGates are the default feature gates for the init command
-var InitFeatureGates = FeatureList{
-	SelfHosting:         {Default: false, PreRelease: utilfeature.Alpha},
-	StoreCertsInSecrets: {Default: false, PreRelease: utilfeature.Alpha},
-}
-
 // KnownFeatures returns a slice of strings describing the FeatureList features.
 func KnownFeatures(f *FeatureList) []string {
 	var known []string

cmd/kubeadm/app/features/features_test.go

@@ -25,9 +25,9 @@ import (
 
 func TestKnownFeatures(t *testing.T) {
 	var someFeatures = FeatureList{
-		"feature2": {Default: true, PreRelease: utilfeature.Alpha},
+		"feature2": {FeatureSpec: utilfeature.FeatureSpec{Default: true, PreRelease: utilfeature.Alpha}},
-		"feature1": {Default: false, PreRelease: utilfeature.Beta},
+		"feature1": {FeatureSpec: utilfeature.FeatureSpec{Default: false, PreRelease: utilfeature.Beta}},
-		"feature3": {Default: false, PreRelease: utilfeature.GA},
+		"feature3": {FeatureSpec: utilfeature.FeatureSpec{Default: false, PreRelease: utilfeature.GA}},
 	}
 
 	r := KnownFeatures(&someFeatures)
@@ -55,8 +55,8 @@ func TestKnownFeatures(t *testing.T) {
 
 func TestNewFeatureGate(t *testing.T) {
 	var someFeatures = FeatureList{
-		"feature1": {Default: false, PreRelease: utilfeature.Beta},
+		"feature1": {FeatureSpec: utilfeature.FeatureSpec{Default: false, PreRelease: utilfeature.Beta}},
-		"feature2": {Default: true, PreRelease: utilfeature.Alpha},
+		"feature2": {FeatureSpec: utilfeature.FeatureSpec{Default: true, PreRelease: utilfeature.Alpha}},
 	}
 
 	var tests = []struct {
@@ -117,3 +117,42 @@ func TestNewFeatureGate(t *testing.T) {
 		}
 	}
 }
+
+func TestValidateVersion(t *testing.T) {
+	var someFeatures = FeatureList{
+		"feature1": {FeatureSpec: utilfeature.FeatureSpec{Default: false, PreRelease: utilfeature.Beta}},
+		"feature2": {FeatureSpec: utilfeature.FeatureSpec{Default: true, PreRelease: utilfeature.Alpha}, MinimumVersion: v190},
+	}
+
+	var tests = []struct {
+		requestedVersion  string
+		requestedFeatures map[string]bool
+		expectedError     bool
+	}{
+		{ //no min version
+			requestedFeatures: map[string]bool{"feature1": true},
+			expectedError:     false,
+		},
+		{ //min version but correct value given
+			requestedFeatures: map[string]bool{"feature2": true},
+			requestedVersion:  "v1.9.0",
+			expectedError:     false,
+		},
+		{ //min version and incorrect value given
+			requestedFeatures: map[string]bool{"feature2": true},
+			requestedVersion:  "v1.8.2",
+			expectedError:     true,
+		},
+	}
+
+	for _, test := range tests {
+		err := ValidateVersion(someFeatures, test.requestedFeatures, test.requestedVersion)
+		if !test.expectedError && err != nil {
+			t.Errorf("ValidateVersion failed when not expected: %v", err)
+			continue
+		} else if test.expectedError && err == nil {
+			t.Error("ValidateVersion didn't failed when expected")
+			continue
+		}
+	}
+}