From eacdc63473f880057f0ec270fcb1f67345d2193f Mon Sep 17 00:00:00 2001
From: Joel May <joel0@users.noreply.github.com>
Date: Thu, 6 Jan 2022 12:57:40 -0800
Subject: [PATCH] Emit metrics for eval waitUntil as
 nomad.nomad.broker.eval_waiting (#10236)

---
 nomad/eval_broker.go | 24 +++++++++++++++++++++---
 1 file changed, 21 insertions(+), 3 deletions(-)

diff --git a/nomad/eval_broker.go b/nomad/eval_broker.go
index 0a6a9f185..bfab5b437 100644
--- a/nomad/eval_broker.go
+++ b/nomad/eval_broker.go
@@ -146,6 +146,7 @@ func NewEvalBroker(timeout, initialNackDelay, subsequentNackDelay time.Duration,
 		delayedEvalsUpdateCh: make(chan struct{}, 1),
 	}
 	b.stats.ByScheduler = make(map[string]*SchedulerStats)
+	b.stats.DelayedEvals = make(map[string]*structs.Evaluation)
 
 	return b, nil
 }
@@ -241,6 +242,7 @@ func (b *EvalBroker) processEnqueue(eval *structs.Evaluation, token string) {
 	if !eval.WaitUntil.IsZero() {
 		b.delayHeap.Push(&evalWrapper{eval}, eval.WaitUntil)
 		b.stats.TotalWaiting += 1
+		b.stats.DelayedEvals[eval.ID] = eval
 		// Signal an update.
 		select {
 		case b.delayedEvalsUpdateCh <- struct{}{}:
@@ -723,6 +725,7 @@ func (b *EvalBroker) flush() {
 	b.stats.TotalUnacked = 0
 	b.stats.TotalBlocked = 0
 	b.stats.TotalWaiting = 0
+	b.stats.DelayedEvals = make(map[string]*structs.Evaluation)
 	b.stats.ByScheduler = make(map[string]*SchedulerStats)
 	b.evals = make(map[string]int)
 	b.jobEvals = make(map[structs.NamespacedID]string)
@@ -777,6 +780,7 @@ func (b *EvalBroker) runDelayedEvalsWatcher(ctx context.Context, updateCh <-chan
 			b.l.Lock()
 			b.delayHeap.Remove(&evalWrapper{eval})
 			b.stats.TotalWaiting -= 1
+			delete(b.stats.DelayedEvals, eval.ID)
 			b.enqueueLocked(eval, eval.Type)
 			b.l.Unlock()
 		case <-updateCh:
@@ -807,6 +811,7 @@ func (b *EvalBroker) nextDelayedEval() (*structs.Evaluation, time.Time) {
 func (b *EvalBroker) Stats() *BrokerStats {
 	// Allocate a new stats struct
 	stats := new(BrokerStats)
+	stats.DelayedEvals = make(map[string]*structs.Evaluation)
 	stats.ByScheduler = make(map[string]*SchedulerStats)
 
 	b.l.RLock()
@@ -817,10 +822,13 @@ func (b *EvalBroker) Stats() *BrokerStats {
 	stats.TotalUnacked = b.stats.TotalUnacked
 	stats.TotalBlocked = b.stats.TotalBlocked
 	stats.TotalWaiting = b.stats.TotalWaiting
+	for id, eval := range b.stats.DelayedEvals {
+		evalCopy := *eval
+		stats.DelayedEvals[id] = &evalCopy
+	}
 	for sched, subStat := range b.stats.ByScheduler {
-		subStatCopy := new(SchedulerStats)
-		*subStatCopy = *subStat
-		stats.ByScheduler[sched] = subStatCopy
+		subStatCopy := *subStat
+		stats.ByScheduler[sched] = &subStatCopy
 	}
 	return stats
 }
@@ -835,6 +843,15 @@ func (b *EvalBroker) EmitStats(period time.Duration, stopCh <-chan struct{}) {
 			metrics.SetGauge([]string{"nomad", "broker", "total_unacked"}, float32(stats.TotalUnacked))
 			metrics.SetGauge([]string{"nomad", "broker", "total_blocked"}, float32(stats.TotalBlocked))
 			metrics.SetGauge([]string{"nomad", "broker", "total_waiting"}, float32(stats.TotalWaiting))
+			for _, eval := range stats.DelayedEvals {
+				metrics.SetGaugeWithLabels([]string{"nomad", "broker", "eval_waiting"},
+					float32(time.Until(eval.WaitUntil).Seconds()),
+					[]metrics.Label{
+						{Name: "eval_id", Value: eval.ID},
+						{Name: "job", Value: eval.JobID},
+						{Name: "namespace", Value: eval.Namespace},
+					})
+			}
 			for sched, schedStats := range stats.ByScheduler {
 				metrics.SetGauge([]string{"nomad", "broker", sched, "ready"}, float32(schedStats.Ready))
 				metrics.SetGauge([]string{"nomad", "broker", sched, "unacked"}, float32(schedStats.Unacked))
@@ -852,6 +869,7 @@ type BrokerStats struct {
 	TotalUnacked int
 	TotalBlocked int
 	TotalWaiting int
+	DelayedEvals map[string]*structs.Evaluation
 	ByScheduler  map[string]*SchedulerStats
 }