startupProbe: API changes

Author: matthyx

pkg/api/pod/util.go

@@ -383,6 +383,14 @@ func dropDisabledFields(
 		})
 	}
 
+	if !utilfeature.DefaultFeatureGate.Enabled(features.StartupProbe) && !startupProbeInUse(oldPodSpec) {
+		// drop startupProbe from all containers if the feature is disabled
+		VisitContainers(podSpec, func(c *api.Container) bool {
+			c.StartupProbe = nil
+			return true
+		})
+	}
+
 	dropDisabledVolumeDevicesFields(podSpec, oldPodSpec)
 
 	dropDisabledRunAsGroupField(podSpec, oldPodSpec)
@@ -819,6 +827,24 @@ func subpathExprInUse(podSpec *api.PodSpec) bool {
 	return inUse
 }
 
+// startupProbeInUse returns true if the pod spec is non-nil and has a container that has a startupProbe defined
+func startupProbeInUse(podSpec *api.PodSpec) bool {
+	if podSpec == nil {
+		return false
+	}
+
+	var inUse bool
+	VisitContainers(podSpec, func(c *api.Container) bool {
+		if c.StartupProbe != nil {
+			inUse = true
+			return false
+		}
+		return true
+	})
+
+	return inUse
+}
+
 // csiInUse returns true if any pod's spec include inline CSI volumes.
 func csiInUse(podSpec *api.PodSpec) bool {
 	if podSpec == nil {

pkg/apis/core/types.go

@@ -1924,7 +1924,7 @@ type Probe struct {
 	// +optional
 	PeriodSeconds int32
 	// Minimum consecutive successes for the probe to be considered successful after having failed.
-	// Must be 1 for liveness.
+	// Must be 1 for liveness and startup.
 	// +optional
 	SuccessThreshold int32
 	// Minimum consecutive failures for the probe to be considered failed after having succeeded.
@@ -2042,6 +2042,8 @@ type Container struct {
 	// +optional
 	ReadinessProbe *Probe
 	// +optional
+	StartupProbe *Probe
+	// +optional
 	Lifecycle *Lifecycle
 	// Required.
 	// +optional
@@ -2090,7 +2092,7 @@ type Lifecycle struct {
 	// +optional
 	PostStart *Handler
 	// PreStop is called immediately before a container is terminated due to an
-	// API request or management event such as liveness probe failure,
+	// API request or management event such as liveness/startup probe failure,
 	// preemption, resource contention, etc. The handler is not called if the
 	// container crashes or exits. The reason for termination is passed to the
 	// handler. The Pod's termination grace period countdown begins before the
@@ -2174,6 +2176,7 @@ type ContainerStatus struct {
 	ImageID      string
 	// +optional
 	ContainerID string
+	Started     *bool
 }
 
 // PodPhase is a label for the condition of a pod at the current time.
@@ -2936,6 +2939,9 @@ type EphemeralContainerCommon struct {
 	// Probes are not allowed for ephemeral containers.
 	// +optional
 	ReadinessProbe *Probe
+	// Probes are not allowed for ephemeral containers.
+	// +optional
+	StartupProbe *Probe
 	// Lifecycle is not allowed for ephemeral containers.
 	// +optional
 	Lifecycle *Lifecycle

pkg/apis/core/validation/validation.go

@@ -2696,6 +2696,9 @@ func validateInitContainers(containers, otherContainers []core.Container, device
 		if ctr.ReadinessProbe != nil {
 			allErrs = append(allErrs, field.Invalid(idxPath.Child("readinessProbe"), ctr.ReadinessProbe, "must not be set for init containers"))
 		}
+		if ctr.StartupProbe != nil {
+			allErrs = append(allErrs, field.Invalid(idxPath.Child("startupProbe"), ctr.StartupProbe, "must not be set for init containers"))
+		}
 	}
 	return allErrs
 }
@@ -2738,6 +2741,11 @@ func validateContainers(containers []core.Container, isInitContainers bool, volu
 		if ctr.LivenessProbe != nil && ctr.LivenessProbe.SuccessThreshold != 1 {
 			allErrs = append(allErrs, field.Invalid(idxPath.Child("livenessProbe", "successThreshold"), ctr.LivenessProbe.SuccessThreshold, "must be 1"))
 		}
+		allErrs = append(allErrs, validateProbe(ctr.StartupProbe, idxPath.Child("startupProbe"))...)
+		// Startup-specific validation
+		if ctr.StartupProbe != nil && ctr.StartupProbe.SuccessThreshold != 1 {
+			allErrs = append(allErrs, field.Invalid(idxPath.Child("startupProbe", "successThreshold"), ctr.StartupProbe.SuccessThreshold, "must be 1"))
+		}
 
 		switch ctr.TerminationMessagePolicy {
 		case core.TerminationMessageReadFile, core.TerminationMessageFallbackToLogsOnError:

pkg/features/kube_features.go

@@ -489,6 +489,12 @@ const (
 	//
 	// Schedule pods evenly across available topology domains.
 	EvenPodsSpread featuregate.Feature = "EvenPodsSpread"
+
+	// owner: @matthyx
+	// alpha: v1.16
+	//
+	// Enables the startupProbe in kubelet worker.
+	StartupProbe featuregate.Feature = "StartupProbe"
 )
 
 func init() {
@@ -569,6 +575,7 @@ var defaultKubernetesFeatureGates = map[featuregate.Feature]featuregate.FeatureS
 	IPv6DualStack:                                  {Default: false, PreRelease: featuregate.Alpha},
 	EndpointSlice:                                  {Default: false, PreRelease: featuregate.Alpha},
 	EvenPodsSpread:                                 {Default: false, PreRelease: featuregate.Alpha},
+	StartupProbe:                                   {Default: false, PreRelease: featuregate.Alpha},
 
 	// inherited features from generic apiserver, relisted here to get a conflict if it is changed
 	// unintentionally on either side:
@@ -592,6 +599,6 @@ var defaultKubernetesFeatureGates = map[featuregate.Feature]featuregate.FeatureS
 
 	// features that enable backwards compatibility but are scheduled to be removed
 	// ...
-	HPAScaleToZero:         {Default: false, PreRelease: featuregate.Alpha},
+	HPAScaleToZero: {Default: false, PreRelease: featuregate.Alpha},
 	LegacyNodeRoleBehavior: {Default: true, PreRelease: featuregate.Alpha},
 }

staging/src/k8s.io/api/core/v1/types.go

@@ -2025,7 +2025,7 @@ type Probe struct {
 	// +optional
 	PeriodSeconds int32 `json:"periodSeconds,omitempty" protobuf:"varint,4,opt,name=periodSeconds"`
 	// Minimum consecutive successes for the probe to be considered successful after having failed.
-	// Defaults to 1. Must be 1 for liveness. Minimum value is 1.
+	// Defaults to 1. Must be 1 for liveness and startup. Minimum value is 1.
 	// +optional
 	SuccessThreshold int32 `json:"successThreshold,omitempty" protobuf:"varint,5,opt,name=successThreshold"`
 	// Minimum consecutive failures for the probe to be considered failed after having succeeded.
@@ -2196,6 +2196,16 @@ type Container struct {
 	// More info: https://kubernetes.io/docs/concepts/workloads/pods/pod-lifecycle#container-probes
 	// +optional
 	ReadinessProbe *Probe `json:"readinessProbe,omitempty" protobuf:"bytes,11,opt,name=readinessProbe"`
+	// StartupProbe indicates that the Pod has successfully initialized.
+	// If specified, no other probes are executed until this completes successfully.
+	// If this probe fails, the Pod will be restarted, just as if the livenessProbe failed.
+	// This can be used to provide different probe parameters at the beginning of a Pod's lifecycle,
+	// when it might take a long time to load data or warm a cache, than during steady-state operation.
+	// This cannot be updated.
+	// This is an alpha feature enabled by the StartupProbe feature flag.
+	// More info: https://kubernetes.io/docs/concepts/workloads/pods/pod-lifecycle#container-probes
+	// +optional
+	StartupProbe *Probe `json:"startupProbe,omitempty" protobuf:"bytes,22,opt,name=startupProbe"`
 	// Actions that the management system should take in response to container lifecycle events.
 	// Cannot be updated.
 	// +optional
@@ -2282,7 +2292,7 @@ type Lifecycle struct {
 	// +optional
 	PostStart *Handler `json:"postStart,omitempty" protobuf:"bytes,1,opt,name=postStart"`
 	// PreStop is called immediately before a container is terminated due to an
-	// API request or management event such as liveness probe failure,
+	// API request or management event such as liveness/startup probe failure,
 	// preemption, resource contention, etc. The handler is not called if the
 	// container crashes or exits. The reason for termination is passed to the
 	// handler. The Pod's termination grace period countdown begins before the
@@ -2390,6 +2400,12 @@ type ContainerStatus struct {
 	// Container's ID in the format 'docker://<container_id>'.
 	// +optional
 	ContainerID string `json:"containerID,omitempty" protobuf:"bytes,8,opt,name=containerID"`
+	// Specifies whether the container has passed its startup probe.
+	// Initialized as false, becomes true after startupProbe is considered successful.
+	// Resets to false when the container is restarted, or if kubelet loses state temporarily.
+	// Is always true when no startupProbe is defined.
+	// +optional
+	Started *bool `json:"started,omitempty" protobuf:"varint,9,opt,name=started"`
 }
 
 // PodPhase is a label for the condition of a pod at the current time.
@@ -2825,7 +2841,7 @@ type PodSpec struct {
 	// init container fails, the pod is considered to have failed and is handled according
 	// to its restartPolicy. The name for an init container or normal container must be
 	// unique among all containers.
-	// Init containers may not have Lifecycle actions, Readiness probes, or Liveness probes.
+	// Init containers may not have Lifecycle actions, Readiness probes, Liveness probes, or Startup probes.
 	// The resourceRequirements of an init container are taken into account during scheduling
 	// by finding the highest request/limit for each resource type, and then using the max of
 	// of that value or the sum of the normal containers. Limits are applied to init containers
@@ -3293,6 +3309,9 @@ type EphemeralContainerCommon struct {
 	// Probes are not allowed for ephemeral containers.
 	// +optional
 	ReadinessProbe *Probe `json:"readinessProbe,omitempty" protobuf:"bytes,11,opt,name=readinessProbe"`
+	// Probes are not allowed for ephemeral containers.
+	// +optional
+	StartupProbe *Probe `json:"startupProbe,omitempty" protobuf:"bytes,22,opt,name=startupProbe"`
 	// Lifecycle is not allowed for ephemeral containers.
 	// +optional
 	Lifecycle *Lifecycle `json:"lifecycle,omitempty" protobuf:"bytes,12,opt,name=lifecycle"`

staging/src/k8s.io/kubectl/pkg/describe/versioned/describe.go

@@ -1707,6 +1707,10 @@ func describeContainerProbe(container corev1.Container, w PrefixWriter) {
 		probe := DescribeProbe(container.ReadinessProbe)
 		w.Write(LEVEL_2, "Readiness:\t%s\n", probe)
 	}
+	if container.StartupProbe != nil {
+		probe := DescribeProbe(container.StartupProbe)
+		w.Write(LEVEL_2, "Startup:\t%s\n", probe)
+	}
 }
 
 func describeContainerVolumes(container corev1.Container, w PrefixWriter) {