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Add a generic labeled gauge for K8s plugin resources (#137)
# TL;DR Adds a generic labeled gauge for K8s plugin resources ## Type - [ ] Bug Fix - [x] Feature - [ ] Plugin ## Are all requirements met? - [x] Code completed - [x] Smoke tested - [x] Unit tests added - [x] Code documentation added - [x] Any pending items have an associated Issue ## Complete description * We are adding a generic utility to emit gauge metrics in the `plugin_manager` using the labeled gauges now found in flytestdlib. * Henceforth, a goroutine will be spun up that will create a `ResourceLevelMonitor` for each type that a plugin registers. * Changing the existing gauge collecting utilty for FlyteWorkflow CRD objects to use the same labeled gauge. * We may wish to combine these in the future but as their aggregations are different, we are keeping them separate for now. ## Tracking Issue flyteorg/flyte#311 ## Follow-up issue NA
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182 changes: 182 additions & 0 deletions
182
flytepropeller/pkg/controller/nodes/task/k8s/plugin_collector.go
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,182 @@ | ||
| package k8s | ||
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| import ( | ||
| "context" | ||
| "runtime/pprof" | ||
| "strings" | ||
| "sync" | ||
| "time" | ||
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| "github.com/lyft/flytestdlib/logger" | ||
| "github.com/lyft/flytestdlib/promutils/labeled" | ||
| "k8s.io/apimachinery/pkg/api/meta" | ||
| "k8s.io/apimachinery/pkg/runtime/schema" | ||
| "k8s.io/client-go/tools/cache" | ||
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| "github.com/lyft/flytestdlib/contextutils" | ||
| "github.com/lyft/flytestdlib/promutils" | ||
| ) | ||
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| const resourceLevelMonitorCycleDuration = 10 * time.Second | ||
| const KindKey contextutils.Key = "kind" | ||
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| // This object is responsible for emitting metrics that show the current number of a given K8s resource kind, cut by namespace. | ||
| // It needs to be kicked off. The periodicity is not currently configurable because it seems unnecessary. It will also | ||
| // a timer measuring how long it takes to run each measurement cycle. | ||
| type ResourceLevelMonitor struct { | ||
| Scope promutils.Scope | ||
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| // Meta timer - this times each collection cycle to measure how long it takes to collect the levels GaugeVec below | ||
| CollectorTimer *labeled.StopWatch | ||
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| // System Observability: This is a labeled gauge that emits the current number of objects in the informer. It is used | ||
| // to monitor current levels. | ||
| Levels *labeled.Gauge | ||
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| // This informer will be used to get a list of the underlying objects that we want a tally of | ||
| sharedInformer cache.SharedIndexInformer | ||
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| // The kind here will be used to differentiate all the metrics, we'll leave out group and version for now | ||
| gvk schema.GroupVersionKind | ||
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| // We only want to create one of these ResourceLevelMonitor objects per K8s resource type. If one of these objects | ||
| // already exists because another plugin created it, we pass along the pointer to that older object. However, we don't | ||
| // want the collection goroutine to be kicked off multiple times. | ||
| once sync.Once | ||
| } | ||
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| // The reason that we use namespace as the one and only thing to cut by is because it's the feature that we are sure that any | ||
| // K8s resource created by a plugin will have (as yet, Flyte doesn't have any plugins that create cluster level resources and | ||
| // it probably won't for a long time). We can't assume that all the operators and CRDs that Flyte will ever work with will have | ||
| // the exact same set of labels or annotations or owner references. The only thing we can really count on is namespace. | ||
| func (r *ResourceLevelMonitor) countList(ctx context.Context, objects []interface{}) map[string]int { | ||
| // Map of namespace to counts | ||
| counts := map[string]int{} | ||
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| // Collect the object counts by namespace | ||
| for _, v := range objects { | ||
| metadata, err := meta.Accessor(v) | ||
| if err != nil { | ||
| logger.Errorf(ctx, "Error converting obj %v to an Accessor %s\n", v, err) | ||
| continue | ||
| } | ||
| counts[metadata.GetNamespace()]++ | ||
| } | ||
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| return counts | ||
| } | ||
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| // The context here is expected to already have a value for the KindKey | ||
| func (r *ResourceLevelMonitor) collect(ctx context.Context) { | ||
| // Emit gauges at the namespace layer - since these are just K8s resources, we cannot be guaranteed to have the necessary | ||
| // information to derive project/domain | ||
| objects := r.sharedInformer.GetStore().List() | ||
| counts := r.countList(ctx, objects) | ||
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| for ns, count := range counts { | ||
| withNamespaceCtx := contextutils.WithNamespace(ctx, ns) | ||
| r.Levels.Set(withNamespaceCtx, float64(count)) | ||
| } | ||
| } | ||
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| func (r *ResourceLevelMonitor) RunCollector(ctx context.Context) { | ||
| ticker := time.NewTicker(resourceLevelMonitorCycleDuration) | ||
| collectorCtx := contextutils.WithGoroutineLabel(ctx, "k8s-resource-level-monitor") | ||
| // Since the idea is that one of these objects is always only responsible for exactly one type of K8s resource, we | ||
| // can safely set the context here for that kind for all downstream usage | ||
| collectorCtx = context.WithValue(ctx, KindKey, strings.ToLower(r.gvk.Kind)) | ||
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| go func() { | ||
| defer ticker.Stop() | ||
| pprof.SetGoroutineLabels(collectorCtx) | ||
| r.sharedInformer.HasSynced() | ||
| logger.Infof(ctx, "K8s resource collector %s has synced", r.gvk.Kind) | ||
| for { | ||
| select { | ||
| case <-collectorCtx.Done(): | ||
| return | ||
| case <-ticker.C: | ||
| t := r.CollectorTimer.Start(collectorCtx) | ||
| r.collect(collectorCtx) | ||
| t.Stop() | ||
| } | ||
| } | ||
| }() | ||
| } | ||
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| func (r *ResourceLevelMonitor) RunCollectorOnce(ctx context.Context) { | ||
| r.once.Do(func() { | ||
| r.RunCollector(ctx) | ||
| }) | ||
| } | ||
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| // This struct is here to ensure that we do not create more than one of these monitors for a given GVK. It wouldn't necessarily break | ||
| // anything, but it's a waste of compute cycles to compute counts multiple times. This can happen if multiple plugins create the same | ||
| // underlying K8s resource type. If two plugins both created Pods (ie sidecar and container), without this we would launch two | ||
| // ResourceLevelMonitor's, have two goroutines spinning, etc. | ||
| type ResourceMonitorIndex struct { | ||
| lock *sync.Mutex | ||
| monitors map[schema.GroupVersionKind]*ResourceLevelMonitor | ||
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| // These are declared here because this constructor will be called more than once, by different K8s resource types (Pods, SparkApps, OtherCrd, etc.) | ||
| // and metric names have to be unique. It felt more reasonable at time of writing to have one metric and have each resource type just be a label | ||
| // rather than one metric per type, but can revisit this down the road. | ||
| gauges map[promutils.Scope]*labeled.Gauge | ||
| stopwatches map[promutils.Scope]*labeled.StopWatch | ||
| } | ||
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| func (r *ResourceMonitorIndex) GetOrCreateResourceLevelMonitor(ctx context.Context, scope promutils.Scope, si cache.SharedIndexInformer, | ||
| gvk schema.GroupVersionKind) *ResourceLevelMonitor { | ||
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| logger.Infof(ctx, "Attempting to create K8s gauge emitter for kind %s/%s", gvk.Version, gvk.Kind) | ||
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| r.lock.Lock() | ||
| defer r.lock.Unlock() | ||
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| if r.monitors[gvk] != nil { | ||
| logger.Infof(ctx, "Monitor for resource type %s already created, skipping...", gvk.Kind) | ||
| return r.monitors[gvk] | ||
| } | ||
| logger.Infof(ctx, "Creating monitor for resource type %s...", gvk.Kind) | ||
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| // Refer to the existing labels in main.go of this repo. For these guys, we need to add namespace and kind (the K8s resource name, pod, sparkapp, etc.) | ||
| additionalLabels := labeled.AdditionalLabelsOption{ | ||
| Labels: []string{contextutils.NamespaceKey.String(), KindKey.String()}, | ||
| } | ||
| if r.gauges[scope] == nil { | ||
| x := labeled.NewGauge("k8s_resources", "Current levels of K8s objects as seen from their informer caches", scope, additionalLabels) | ||
| r.gauges[scope] = &x | ||
| } | ||
| if r.stopwatches[scope] == nil { | ||
| x := labeled.NewStopWatch("k8s_collection_cycle", "Measures how long it takes to run a collection", | ||
| time.Millisecond, scope, additionalLabels) | ||
| r.stopwatches[scope] = &x | ||
| } | ||
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| rm := &ResourceLevelMonitor{ | ||
| Scope: scope, | ||
| CollectorTimer: r.stopwatches[scope], | ||
| Levels: r.gauges[scope], | ||
| sharedInformer: si, | ||
| gvk: gvk, | ||
| } | ||
| r.monitors[gvk] = rm | ||
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| return rm | ||
| } | ||
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| // This is a global variable to this file. At runtime, the NewResourceMonitorIndex() function should only be called once | ||
| // but can be called multiple times in unit tests. | ||
| var index *ResourceMonitorIndex | ||
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| func NewResourceMonitorIndex() *ResourceMonitorIndex { | ||
| if index == nil { | ||
| index = &ResourceMonitorIndex{ | ||
| lock: &sync.Mutex{}, | ||
| monitors: make(map[schema.GroupVersionKind]*ResourceLevelMonitor), | ||
| gauges: make(map[promutils.Scope]*labeled.Gauge), | ||
| stopwatches: make(map[promutils.Scope]*labeled.StopWatch), | ||
| } | ||
| } | ||
| return index | ||
| } |
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