/* Copyright 2022 The Kubernetes Authors. Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with the License. You may obtain a copy of the License at http://www.apache.org/licenses/LICENSE-2.0 Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the specific language governing permissions and limitations under the License. */ package util import ( "sync" "time" v1 "k8s.io/api/core/v1" "k8s.io/apimachinery/pkg/types" "k8s.io/klog/v2" "k8s.io/kubernetes/pkg/kubelet/metrics" "k8s.io/utils/clock" ) // PodStartupLatencyTracker records key moments for startup latency calculation, // e.g. image pulling or pod observed running on watch. type PodStartupLatencyTracker interface { ObservedPodOnWatch(pod *v1.Pod, when time.Time) RecordImageStartedPulling(podUID types.UID) RecordImageFinishedPulling(podUID types.UID) RecordStatusUpdated(pod *v1.Pod) DeletePodStartupState(podUID types.UID) } type basicPodStartupLatencyTracker struct { // protect against concurrent read and write on pods map lock sync.Mutex pods map[types.UID]*perPodState // metrics for the first network pod only firstNetworkPodSeen bool // For testability clock clock.Clock } type perPodState struct { firstStartedPulling time.Time lastFinishedPulling time.Time // first time, when pod status changed into Running observedRunningTime time.Time // log, if pod latency was already Observed metricRecorded bool } // NewPodStartupLatencyTracker creates an instance of PodStartupLatencyTracker func NewPodStartupLatencyTracker() PodStartupLatencyTracker { return &basicPodStartupLatencyTracker{ pods: map[types.UID]*perPodState{}, clock: clock.RealClock{}, } } func (p *basicPodStartupLatencyTracker) ObservedPodOnWatch(pod *v1.Pod, when time.Time) { p.lock.Lock() defer p.lock.Unlock() // if the pod is terminal, we do not have to track it anymore for startup if pod.Status.Phase == v1.PodFailed || pod.Status.Phase == v1.PodSucceeded { delete(p.pods, pod.UID) return } state := p.pods[pod.UID] if state == nil { // create a new record for pod, only if it was not yet acknowledged by the Kubelet // this is required, as we want to log metric only for those pods, that where scheduled // after Kubelet started if pod.Status.StartTime.IsZero() { p.pods[pod.UID] = &perPodState{} } return } if state.observedRunningTime.IsZero() { // skip, pod didn't start yet return } if state.metricRecorded { // skip, pod's latency already recorded return } if hasPodStartedSLO(pod) { podStartingDuration := when.Sub(pod.CreationTimestamp.Time) imagePullingDuration := state.lastFinishedPulling.Sub(state.firstStartedPulling) podStartSLOduration := (podStartingDuration - imagePullingDuration).Seconds() klog.InfoS("Observed pod startup duration", "pod", klog.KObj(pod), "podStartSLOduration", podStartSLOduration, "podStartE2EDuration", podStartingDuration, "podCreationTimestamp", pod.CreationTimestamp.Time, "firstStartedPulling", state.firstStartedPulling, "lastFinishedPulling", state.lastFinishedPulling, "observedRunningTime", state.observedRunningTime, "watchObservedRunningTime", when) metrics.PodStartSLIDuration.WithLabelValues().Observe(podStartSLOduration) metrics.PodStartTotalDuration.WithLabelValues().Observe(podStartingDuration.Seconds()) state.metricRecorded = true // if is the first Pod with network track the start values // these metrics will help to identify problems with the CNI plugin if !pod.Spec.HostNetwork && !p.firstNetworkPodSeen { metrics.FirstNetworkPodStartSLIDuration.Set(podStartSLOduration) p.firstNetworkPodSeen = true } } } func (p *basicPodStartupLatencyTracker) RecordImageStartedPulling(podUID types.UID) { p.lock.Lock() defer p.lock.Unlock() state := p.pods[podUID] if state == nil { return } if state.firstStartedPulling.IsZero() { state.firstStartedPulling = p.clock.Now() } } func (p *basicPodStartupLatencyTracker) RecordImageFinishedPulling(podUID types.UID) { p.lock.Lock() defer p.lock.Unlock() state := p.pods[podUID] if state == nil { return } state.lastFinishedPulling = p.clock.Now() // Now is always grater than values from the past. } func (p *basicPodStartupLatencyTracker) RecordStatusUpdated(pod *v1.Pod) { p.lock.Lock() defer p.lock.Unlock() state := p.pods[pod.UID] if state == nil { return } if state.metricRecorded { // skip, pod latency already recorded return } if !state.observedRunningTime.IsZero() { // skip, pod already started return } if hasPodStartedSLO(pod) { klog.V(3).InfoS("Mark when the pod was running for the first time", "pod", klog.KObj(pod), "rv", pod.ResourceVersion) state.observedRunningTime = p.clock.Now() } } // hasPodStartedSLO, check if for given pod, each container has been started at least once // // This should reflect "Pod startup latency SLI" definition // ref: https://github.com/kubernetes/community/blob/master/sig-scalability/slos/pod_startup_latency.md func hasPodStartedSLO(pod *v1.Pod) bool { for _, cs := range pod.Status.ContainerStatuses { if cs.State.Running == nil || cs.State.Running.StartedAt.IsZero() { return false } } return true } func (p *basicPodStartupLatencyTracker) DeletePodStartupState(podUID types.UID) { p.lock.Lock() defer p.lock.Unlock() delete(p.pods, podUID) }