Add DownwardMetrics feature gate (#2837)

It adds the `DownwardMetrics` feature gate to HCO. It allows users to
disable this feature in KubeVirt.

Signed-off-by: Javier Cano Cano <jcanocan@redhat.com>
Co-authored-by: Javier Cano Cano <jcanocan@redhat.com>

api/v1beta1/hyperconverged_types.go

@@ -375,6 +375,10 @@ type VirtualMachineOptions struct {
 // by default yet.
 // +k8s:openapi-gen=true
 type HyperConvergedFeatureGates struct {
+	// Allow to expose a limited set of host metrics to guests.
+	// +optional
+	DownwardMetrics *bool `json:"downwardMetrics,omitempty"`
+
 	// Allow migrating a virtual machine with CPU host-passthrough mode. This should be
 	// enabled only when the Cluster is homogeneous from CPU HW perspective doc here
 	// +optional

config/crd/bases/hco.kubevirt.io_hyperconvergeds.yaml

@@ -1194,6 +1194,10 @@ spec:
                     default: false
                     description: Disable mediated devices handling on KubeVirt
                     type: boolean
+                  downwardMetrics:
+                    description: Allow to expose a limited set of host metrics to
+                      guests.
+                    type: boolean
                   enableApplicationAwareQuota:
                     default: false
                     description: EnableApplicationAwareQuota if true, enables the

controllers/operands/kubevirt.go

@@ -85,9 +85,6 @@ const (
 	// Allow assigning host devices to virtual machines
 	kvHostDevicesGate = "HostDevices"
 
-	// Add downwardMetrics volume to expose a limited set of host metrics to guests
-	kvDownwardMetricsGate = "DownwardMetrics"
-
 	// Expand disks to the largest size
 	kvExpandDisksGate = "ExpandDisks"
 
@@ -129,7 +126,6 @@ var (
 		kvExpandDisksGate,
 		kvGPUGate,
 		kvHostDevicesGate,
-		kvDownwardMetricsGate,
 		kvNUMA,
 		kvVMExportGate,
 		kvDisableCustomSELinuxPolicyGate,
@@ -162,6 +158,7 @@ var (
 
 // KubeVirt feature gates that are exposed in HCO API
 const (
+	kvDownwardMetrics        = "DownwardMetrics"
 	kvWithHostPassthroughCPU = "WithHostPassthroughCPU"
 	kvRoot                   = "Root"
 	kvDisableMDevConfig      = "DisableMDEVConfiguration"
@@ -751,6 +748,10 @@ func hcoConfig2KvConfig(hcoConfig hcov1beta1.HyperConvergedConfig, infrastructur
 func getFeatureGateChecks(featureGates *hcov1beta1.HyperConvergedFeatureGates) []string {
 	fgs := make([]string, 0, 2)
 
+	if featureGates.DownwardMetrics == nil || *featureGates.DownwardMetrics {
+		fgs = append(fgs, kvDownwardMetrics)
+	}
+
 	if featureGates.WithHostPassthroughCPU != nil && *featureGates.WithHostPassthroughCPU {
 		fgs = append(fgs, kvWithHostPassthroughCPU)
 	}
@@ -880,8 +881,11 @@ func getMandatoryKvFeatureGates(isKVMEmulation bool) []string {
 // get list of feature gates or KV FG list
 func getKvFeatureGateList(fgs *hcov1beta1.HyperConvergedFeatureGates) []string {
 	checks := getFeatureGateChecks(fgs)
+
 	res := make([]string, 0, len(checks)+len(mandatoryKvFeatureGates)+1)
+
 	res = append(res, mandatoryKvFeatureGates...)
+
 	res = append(res, checks...)
 
 	return res

controllers/operands/kubevirt_test.go

@@ -28,6 +28,9 @@ import (
 )
 
 var _ = Describe("KubeVirt Operand", func() {
+	// DownwardMetrics FG is not listed on any of these lists, but it is enabled by default
+	const enabledByDefaultFeatureGates = 1
+
 	var (
 		basicNumFgOnOpenshift = len(hardCodeKvFgs) + len(sspConditionKvFgs)
 	)
@@ -217,7 +220,7 @@ Version: 1.2.3`)
 			Expect(foundResource.Namespace).To(Equal(expectedResource.Namespace))
 
 			Expect(foundResource.Spec.Configuration.DeveloperConfiguration).ToNot(BeNil())
-			Expect(foundResource.Spec.Configuration.DeveloperConfiguration.FeatureGates).To(HaveLen(basicNumFgOnOpenshift + 1))
+			Expect(foundResource.Spec.Configuration.DeveloperConfiguration.FeatureGates).To(HaveLen(basicNumFgOnOpenshift + 1 + enabledByDefaultFeatureGates))
 			Expect(foundResource.Spec.Configuration.DeveloperConfiguration.FeatureGates).To(ContainElements(
 				hardCodeKvFgs,
 			))
@@ -427,7 +430,7 @@ Version: 1.2.3`)
 					foundResource),
 			).ToNot(HaveOccurred())
 			Expect(foundResource.Spec.Configuration.DeveloperConfiguration).ToNot(BeNil())
-			Expect(foundResource.Spec.Configuration.DeveloperConfiguration.FeatureGates).To(HaveLen(basicNumFgOnOpenshift + 1))
+			Expect(foundResource.Spec.Configuration.DeveloperConfiguration.FeatureGates).To(HaveLen(basicNumFgOnOpenshift + 1 + enabledByDefaultFeatureGates))
 			Expect(foundResource.Spec.Configuration.DeveloperConfiguration.FeatureGates).To(ContainElements(
 				hardCodeKvFgs,
 			))
@@ -1797,10 +1800,49 @@ Version: 1.2.3`)
 
 					Expect(existingResource.Spec.Configuration.DeveloperConfiguration).ToNot(BeNil())
 					fgList := getKvFeatureGateList(&hco.Spec.FeatureGates)
-					Expect(fgList).To(HaveLen(basicNumFgOnOpenshift))
+					Expect(fgList).To(HaveLen(basicNumFgOnOpenshift + enabledByDefaultFeatureGates))
 					Expect(fgList).Should(ContainElements(hardCodeKvFgs))
 					Expect(fgList).Should(ContainElements(sspConditionKvFgs))
 				})
+
+				It("should add the DownwardMetrics if feature gate DownwardMetrics is true in HyperConverged CR", func() {
+					hco.Spec.FeatureGates = hcov1beta1.HyperConvergedFeatureGates{
+						DownwardMetrics: ptr.To(true),
+					}
+
+					existingResource, err := NewKubeVirt(hco)
+					Expect(err).ToNot(HaveOccurred())
+					By("KV CR should contain the DownwardMetrics feature gate", func() {
+						Expect(existingResource.Spec.Configuration.DeveloperConfiguration).NotTo(BeNil())
+						Expect(existingResource.Spec.Configuration.DeveloperConfiguration.FeatureGates).To(ContainElement(kvDownwardMetrics))
+					})
+				})
+
+				It("should add the DownwardMetrics if feature gate DownwardMetrics is not in HyperConverged CR", func() {
+					hco.Spec.FeatureGates = hcov1beta1.HyperConvergedFeatureGates{
+						DownwardMetrics: nil,
+					}
+
+					existingResource, err := NewKubeVirt(hco)
+					Expect(err).ToNot(HaveOccurred())
+					By("KV CR should contain the DownwardMetrics feature gate", func() {
+						Expect(existingResource.Spec.Configuration.DeveloperConfiguration).NotTo(BeNil())
+						Expect(existingResource.Spec.Configuration.DeveloperConfiguration.FeatureGates).To(ContainElement(kvDownwardMetrics))
+					})
+				})
+
+				It("should not add the DownwardMetrics if feature gate DownwardMetrics is set to false in HyperConverged CR", func() {
+					hco.Spec.FeatureGates = hcov1beta1.HyperConvergedFeatureGates{
+						DownwardMetrics: ptr.To(false),
+					}
+
+					existingResource, err := NewKubeVirt(hco)
+					Expect(err).ToNot(HaveOccurred())
+					By("KV CR should not contain the DownwardMetrics feature gate", func() {
+						Expect(existingResource.Spec.Configuration.DeveloperConfiguration).NotTo(BeNil())
+						Expect(existingResource.Spec.Configuration.DeveloperConfiguration.FeatureGates).ToNot(ContainElement(kvDownwardMetrics))
+					})
+				})
 			})
 
 			Context("test feature gates in KV handler", func() {
@@ -1876,7 +1918,7 @@ Version: 1.2.3`)
 						mandatoryKvFeatureGates = getMandatoryKvFeatureGates(false)
 						Expect(foundResource.Spec.Configuration.DeveloperConfiguration).ToNot(BeNil())
 						fgList := getKvFeatureGateList(&hco.Spec.FeatureGates)
-						Expect(fgList).To(HaveLen(basicNumFgOnOpenshift))
+						Expect(fgList).To(HaveLen(basicNumFgOnOpenshift + enabledByDefaultFeatureGates))
 						Expect(fgList).Should(ContainElements(hardCodeKvFgs))
 						Expect(fgList).Should(ContainElements(sspConditionKvFgs))
 					})
@@ -1907,15 +1949,16 @@ Version: 1.2.3`)
 						mandatoryKvFeatureGates = getMandatoryKvFeatureGates(false)
 						Expect(foundResource.Spec.Configuration.DeveloperConfiguration).ToNot(BeNil())
 						fgList := getKvFeatureGateList(&hco.Spec.FeatureGates)
-						Expect(fgList).To(HaveLen(basicNumFgOnOpenshift))
+						Expect(fgList).To(HaveLen(len(getKvFeatureGateList(&hco.Spec.FeatureGates))))
 						Expect(fgList).Should(ContainElements(hardCodeKvFgs))
 						Expect(fgList).Should(ContainElements(sspConditionKvFgs))
 					})
 				})
 
 				It("should keep FG if already exist", func() {
 					mandatoryKvFeatureGates = getMandatoryKvFeatureGates(true)
-					fgs := append(hardCodeKvFgs, kvWithHostPassthroughCPU)
+					fgs := getKvFeatureGateList(&hco.Spec.FeatureGates)
+					fgs = append(fgs, kvWithHostPassthroughCPU)
 					existingResource, err := NewKubeVirt(hco)
 					Expect(err).ToNot(HaveOccurred())
 					existingResource.Spec.Configuration.DeveloperConfiguration.FeatureGates = fgs
@@ -1985,7 +2028,7 @@ Version: 1.2.3`)
 					).ToNot(HaveOccurred())
 
 					Expect(foundResource.Spec.Configuration.DeveloperConfiguration).ToNot(BeNil())
-					Expect(foundResource.Spec.Configuration.DeveloperConfiguration.FeatureGates).To(HaveLen(basicNumFgOnOpenshift))
+					Expect(foundResource.Spec.Configuration.DeveloperConfiguration.FeatureGates).To(HaveLen(len(getKvFeatureGateList(&hco.Spec.FeatureGates))))
 					Expect(foundResource.Spec.Configuration.DeveloperConfiguration.FeatureGates).To(ContainElements(hardCodeKvFgs))
 					Expect(foundResource.Spec.Configuration.DeveloperConfiguration.FeatureGates).To(ContainElements(sspConditionKvFgs))
 				})
@@ -2022,7 +2065,7 @@ Version: 1.2.3`)
 					).ToNot(HaveOccurred())
 
 					Expect(foundResource.Spec.Configuration.DeveloperConfiguration).ToNot(BeNil())
-					Expect(foundResource.Spec.Configuration.DeveloperConfiguration.FeatureGates).To(HaveLen(basicNumFgOnOpenshift))
+					Expect(foundResource.Spec.Configuration.DeveloperConfiguration.FeatureGates).To(HaveLen(len(getKvFeatureGateList(&hco.Spec.FeatureGates))))
 					Expect(foundResource.Spec.Configuration.DeveloperConfiguration.FeatureGates).To(ContainElements(hardCodeKvFgs))
 					Expect(foundResource.Spec.Configuration.DeveloperConfiguration.FeatureGates).To(ContainElements(sspConditionKvFgs))
 				})
@@ -2059,7 +2102,7 @@ Version: 1.2.3`)
 					).ToNot(HaveOccurred())
 
 					Expect(foundResource.Spec.Configuration.DeveloperConfiguration).ToNot(BeNil())
-					Expect(foundResource.Spec.Configuration.DeveloperConfiguration.FeatureGates).To(HaveLen(len(hardCodeKvFgs)))
+					Expect(foundResource.Spec.Configuration.DeveloperConfiguration.FeatureGates).To(HaveLen(len(hardCodeKvFgs) + enabledByDefaultFeatureGates))
 					Expect(foundResource.Spec.Configuration.DeveloperConfiguration.FeatureGates).To(ContainElements(hardCodeKvFgs))
 				})
 			})
@@ -2090,37 +2133,37 @@ Version: 1.2.3`)
 					Entry("When not using kvm-emulation and FG is empty",
 						false,
 						&hcov1beta1.HyperConvergedFeatureGates{},
-						basicNumFgOnOpenshift,
+						basicNumFgOnOpenshift+enabledByDefaultFeatureGates,
 						[][]string{hardCodeKvFgs, sspConditionKvFgs},
 					),
 					Entry("When using kvm-emulation and FG is empty",
 						true,
 						&hcov1beta1.HyperConvergedFeatureGates{},
-						len(hardCodeKvFgs),
+						len(hardCodeKvFgs)+enabledByDefaultFeatureGates,
 						[][]string{hardCodeKvFgs},
 					),
 					Entry("When not using kvm-emulation and all FGs are disabled",
 						false,
 						&hcov1beta1.HyperConvergedFeatureGates{WithHostPassthroughCPU: ptr.To(false)},
-						basicNumFgOnOpenshift,
+						basicNumFgOnOpenshift+enabledByDefaultFeatureGates,
 						[][]string{hardCodeKvFgs, sspConditionKvFgs},
 					),
 					Entry("When using kvm-emulation all FGs are disabled",
 						true,
 						&hcov1beta1.HyperConvergedFeatureGates{WithHostPassthroughCPU: ptr.To(false)},
-						len(hardCodeKvFgs),
+						len(hardCodeKvFgs)+enabledByDefaultFeatureGates,
 						[][]string{hardCodeKvFgs},
 					),
 					Entry("When not using kvm-emulation and all FGs are enabled",
 						false,
 						&hcov1beta1.HyperConvergedFeatureGates{WithHostPassthroughCPU: ptr.To(true)},
-						basicNumFgOnOpenshift+1,
+						basicNumFgOnOpenshift+1+enabledByDefaultFeatureGates,
 						[][]string{hardCodeKvFgs, sspConditionKvFgs, {kvWithHostPassthroughCPU}},
 					),
 					Entry("When using kvm-emulation all FGs are enabled",
 						true,
 						&hcov1beta1.HyperConvergedFeatureGates{WithHostPassthroughCPU: ptr.To(true)},
-						len(hardCodeKvFgs)+1,
+						len(hardCodeKvFgs)+1+enabledByDefaultFeatureGates,
 						[][]string{hardCodeKvFgs, {kvWithHostPassthroughCPU}},
 					))
 			})
@@ -3645,7 +3688,7 @@ Version: 1.2.3`)
 				).ToNot(HaveOccurred())
 
 				Expect(kv.Spec.Configuration.DeveloperConfiguration).ToNot(BeNil())
-				Expect(kv.Spec.Configuration.DeveloperConfiguration.FeatureGates).To(HaveLen(len(mandatoryKvFeatureGates)))
+				Expect(kv.Spec.Configuration.DeveloperConfiguration.FeatureGates).To(HaveLen(len(getKvFeatureGateList(&hco.Spec.FeatureGates))))
 				Expect(kv.Spec.Configuration.DeveloperConfiguration.FeatureGates).To(ContainElements(hardCodeKvFgs))
 				Expect(kv.Spec.Configuration.DeveloperConfiguration.FeatureGates).To(ContainElement(kvSRIOVGate))
 				Expect(kv.Spec.Configuration.CPURequest).To(BeNil())

deploy/crds/hco00.crd.yaml

@@ -1194,6 +1194,10 @@ spec:
                     default: false
                     description: Disable mediated devices handling on KubeVirt
                     type: boolean
+                  downwardMetrics:
+                    description: Allow to expose a limited set of host metrics to
+                      guests.
+                    type: boolean
                   enableApplicationAwareQuota:
                     default: false
                     description: EnableApplicationAwareQuota if true, enables the

deploy/index-image/community-kubevirt-hyperconverged/1.11.1/manifests/hco00.crd.yaml

@@ -1194,6 +1194,10 @@ spec:
                     default: false
                     description: Disable mediated devices handling on KubeVirt
                     type: boolean
+                  downwardMetrics:
+                    description: Allow to expose a limited set of host metrics to
+                      guests.
+                    type: boolean
                   enableApplicationAwareQuota:
                     default: false
                     description: EnableApplicationAwareQuota if true, enables the

deploy/olm-catalog/community-kubevirt-hyperconverged/1.11.1/manifests/hco00.crd.yaml

@@ -1194,6 +1194,10 @@ spec:
                     default: false
                     description: Disable mediated devices handling on KubeVirt
                     type: boolean
+                  downwardMetrics:
+                    description: Allow to expose a limited set of host metrics to
+                      guests.
+                    type: boolean
                   enableApplicationAwareQuota:
                     default: false
                     description: EnableApplicationAwareQuota if true, enables the

docs/api.md

@@ -140,6 +140,7 @@ HyperConvergedFeatureGates is a set of optional feature gates to enable or disab
 
 | Field | Description | Scheme | Default | Required |
 | ----- | ----------- | ------ | -------- |-------- |
+| downwardMetrics | Allow to expose a limited set of host metrics to guests. | *bool |  | false |
 | withHostPassthroughCPU | Allow migrating a virtual machine with CPU host-passthrough mode. This should be enabled only when the Cluster is homogeneous from CPU HW perspective doc here | *bool | false | false |
 | enableCommonBootImageImport | Opt-in to automatic delivery/updates of the common data import cron templates. There are two sources for the data import cron templates: hard coded list of common templates, and custom templates that can be added to the dataImportCronTemplates field. This feature gates only control the common templates. It is possible to use custom templates by adding them to the dataImportCronTemplates field. | *bool | true | false |
 | deployTektonTaskResources | deploy resources (kubevirt tekton tasks and example pipelines) in SSP operator | *bool | false | false |

docs/cluster-configuration.md

@@ -130,6 +130,17 @@ or new features that are not enabled by default.
 To enable a feature, add its name to the `featureGates` list and set it to `true`. Missing or `false` feature gates
 disables the feature.
 
+### downwardMetrics Feature Gate
+Set the `downwardMetrics` feature gate in order to allow exposing a limited set of VM and host metrics to the guest.
+The format is compatible with [vhostmd](https://github.com/vhostmd/vhostmd).
+These metrics allow third-parties diagnosing issues.
+DownwardMetrics may be exposed to the guest through a `volume` or a `virtio-serial port`.
+
+By default, if the `downwardMetrics` is not set to `false`, the metrics will be available to the guests.
+This means that updates from previous versions will not require any special configuration.
+
+**Note**: In future versions, the feature gate will be disabled by default.
+
 ### withHostPassthroughCPU Feature Gate
 Set the `withHostPassthroughCPU` feature gate in order to allow migrating a virtual machine with CPU host-passthrough
 mode. This can provide slightly better CPU performance, but should be enabled only when the Cluster is homogeneous from