prometheus/rules/group.go

1015 lines
31 KiB
Go

// Copyright 2013 The Prometheus 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 rules
import (
"context"
"errors"
"math"
"strings"
"sync"
"time"
"go.uber.org/atomic"
"golang.org/x/exp/slices"
"github.com/prometheus/prometheus/promql/parser"
"github.com/go-kit/log"
"github.com/go-kit/log/level"
"github.com/prometheus/client_golang/prometheus"
"github.com/prometheus/common/model"
"go.opentelemetry.io/otel"
"go.opentelemetry.io/otel/attribute"
"go.opentelemetry.io/otel/codes"
"github.com/prometheus/prometheus/model/labels"
"github.com/prometheus/prometheus/model/timestamp"
"github.com/prometheus/prometheus/model/value"
"github.com/prometheus/prometheus/promql"
"github.com/prometheus/prometheus/storage"
"github.com/prometheus/prometheus/tsdb/chunkenc"
)
// Group is a set of rules that have a logical relation.
type Group struct {
name string
file string
interval time.Duration
limit int
rules []Rule
seriesInPreviousEval []map[string]labels.Labels // One per Rule.
staleSeries []labels.Labels
opts *ManagerOptions
mtx sync.Mutex
evaluationTime time.Duration
lastEvaluation time.Time // Wall-clock time of most recent evaluation.
lastEvalTimestamp time.Time // Time slot used for most recent evaluation.
shouldRestore bool
markStale bool
done chan struct{}
terminated chan struct{}
managerDone chan struct{}
logger log.Logger
metrics *Metrics
// Rule group evaluation iteration function,
// defaults to DefaultEvalIterationFunc.
evalIterationFunc GroupEvalIterationFunc
// concurrencyController controls the rules evaluation concurrency.
concurrencyController RuleConcurrencyController
}
// GroupEvalIterationFunc is used to implement and extend rule group
// evaluation iteration logic. It is configured in Group.evalIterationFunc,
// and periodically invoked at each group evaluation interval to
// evaluate the rules in the group at that point in time.
// DefaultEvalIterationFunc is the default implementation.
type GroupEvalIterationFunc func(ctx context.Context, g *Group, evalTimestamp time.Time)
type GroupOptions struct {
Name, File string
Interval time.Duration
Limit int
Rules []Rule
ShouldRestore bool
Opts *ManagerOptions
done chan struct{}
EvalIterationFunc GroupEvalIterationFunc
}
// NewGroup makes a new Group with the given name, options, and rules.
func NewGroup(o GroupOptions) *Group {
metrics := o.Opts.Metrics
if metrics == nil {
metrics = NewGroupMetrics(o.Opts.Registerer)
}
key := GroupKey(o.File, o.Name)
metrics.IterationsMissed.WithLabelValues(key)
metrics.IterationsScheduled.WithLabelValues(key)
metrics.EvalTotal.WithLabelValues(key)
metrics.EvalFailures.WithLabelValues(key)
metrics.GroupLastEvalTime.WithLabelValues(key)
metrics.GroupLastDuration.WithLabelValues(key)
metrics.GroupRules.WithLabelValues(key).Set(float64(len(o.Rules)))
metrics.GroupSamples.WithLabelValues(key)
metrics.GroupInterval.WithLabelValues(key).Set(o.Interval.Seconds())
evalIterationFunc := o.EvalIterationFunc
if evalIterationFunc == nil {
evalIterationFunc = DefaultEvalIterationFunc
}
concurrencyController := o.Opts.RuleConcurrencyController
if concurrencyController == nil {
concurrencyController = sequentialRuleEvalController{}
}
return &Group{
name: o.Name,
file: o.File,
interval: o.Interval,
limit: o.Limit,
rules: o.Rules,
shouldRestore: o.ShouldRestore,
opts: o.Opts,
seriesInPreviousEval: make([]map[string]labels.Labels, len(o.Rules)),
done: make(chan struct{}),
managerDone: o.done,
terminated: make(chan struct{}),
logger: log.With(o.Opts.Logger, "file", o.File, "group", o.Name),
metrics: metrics,
evalIterationFunc: evalIterationFunc,
concurrencyController: concurrencyController,
}
}
// Name returns the group name.
func (g *Group) Name() string { return g.name }
// File returns the group's file.
func (g *Group) File() string { return g.file }
// Rules returns the group's rules.
func (g *Group) Rules() []Rule { return g.rules }
// Queryable returns the group's querable.
func (g *Group) Queryable() storage.Queryable { return g.opts.Queryable }
// Context returns the group's context.
func (g *Group) Context() context.Context { return g.opts.Context }
// Interval returns the group's interval.
func (g *Group) Interval() time.Duration { return g.interval }
// Limit returns the group's limit.
func (g *Group) Limit() int { return g.limit }
func (g *Group) Logger() log.Logger { return g.logger }
func (g *Group) run(ctx context.Context) {
defer close(g.terminated)
// Wait an initial amount to have consistently slotted intervals.
evalTimestamp := g.EvalTimestamp(time.Now().UnixNano()).Add(g.interval)
select {
case <-time.After(time.Until(evalTimestamp)):
case <-g.done:
return
}
ctx = promql.NewOriginContext(ctx, map[string]interface{}{
"ruleGroup": map[string]string{
"file": g.File(),
"name": g.Name(),
},
})
// The assumption here is that since the ticker was started after having
// waited for `evalTimestamp` to pass, the ticks will trigger soon
// after each `evalTimestamp + N * g.interval` occurrence.
tick := time.NewTicker(g.interval)
defer tick.Stop()
defer func() {
if !g.markStale {
return
}
go func(now time.Time) {
for _, rule := range g.seriesInPreviousEval {
for _, r := range rule {
g.staleSeries = append(g.staleSeries, r)
}
}
// That can be garbage collected at this point.
g.seriesInPreviousEval = nil
// Wait for 2 intervals to give the opportunity to renamed rules
// to insert new series in the tsdb. At this point if there is a
// renamed rule, it should already be started.
select {
case <-g.managerDone:
case <-time.After(2 * g.interval):
g.cleanupStaleSeries(ctx, now)
}
}(time.Now())
}()
g.evalIterationFunc(ctx, g, evalTimestamp)
if g.shouldRestore {
// If we have to restore, we wait for another Eval to finish.
// The reason behind this is, during first eval (or before it)
// we might not have enough data scraped, and recording rules would not
// have updated the latest values, on which some alerts might depend.
select {
case <-g.done:
return
case <-tick.C:
missed := (time.Since(evalTimestamp) / g.interval) - 1
if missed > 0 {
g.metrics.IterationsMissed.WithLabelValues(GroupKey(g.file, g.name)).Add(float64(missed))
g.metrics.IterationsScheduled.WithLabelValues(GroupKey(g.file, g.name)).Add(float64(missed))
}
evalTimestamp = evalTimestamp.Add((missed + 1) * g.interval)
g.evalIterationFunc(ctx, g, evalTimestamp)
}
g.RestoreForState(time.Now())
g.shouldRestore = false
}
for {
select {
case <-g.done:
return
default:
select {
case <-g.done:
return
case <-tick.C:
missed := (time.Since(evalTimestamp) / g.interval) - 1
if missed > 0 {
g.metrics.IterationsMissed.WithLabelValues(GroupKey(g.file, g.name)).Add(float64(missed))
g.metrics.IterationsScheduled.WithLabelValues(GroupKey(g.file, g.name)).Add(float64(missed))
}
evalTimestamp = evalTimestamp.Add((missed + 1) * g.interval)
g.evalIterationFunc(ctx, g, evalTimestamp)
}
}
}
}
func (g *Group) stop() {
close(g.done)
<-g.terminated
}
func (g *Group) hash() uint64 {
l := labels.New(
labels.Label{Name: "name", Value: g.name},
labels.Label{Name: "file", Value: g.file},
)
return l.Hash()
}
// AlertingRules returns the list of the group's alerting rules.
func (g *Group) AlertingRules() []*AlertingRule {
g.mtx.Lock()
defer g.mtx.Unlock()
var alerts []*AlertingRule
for _, rule := range g.rules {
if alertingRule, ok := rule.(*AlertingRule); ok {
alerts = append(alerts, alertingRule)
}
}
slices.SortFunc(alerts, func(a, b *AlertingRule) int {
if a.State() == b.State() {
return strings.Compare(a.Name(), b.Name())
}
return int(b.State() - a.State())
})
return alerts
}
// HasAlertingRules returns true if the group contains at least one AlertingRule.
func (g *Group) HasAlertingRules() bool {
g.mtx.Lock()
defer g.mtx.Unlock()
for _, rule := range g.rules {
if _, ok := rule.(*AlertingRule); ok {
return true
}
}
return false
}
// GetEvaluationTime returns the time in seconds it took to evaluate the rule group.
func (g *Group) GetEvaluationTime() time.Duration {
g.mtx.Lock()
defer g.mtx.Unlock()
return g.evaluationTime
}
// setEvaluationTime sets the time in seconds the last evaluation took.
func (g *Group) setEvaluationTime(dur time.Duration) {
g.metrics.GroupLastDuration.WithLabelValues(GroupKey(g.file, g.name)).Set(dur.Seconds())
g.mtx.Lock()
defer g.mtx.Unlock()
g.evaluationTime = dur
}
// GetLastEvaluation returns the time the last evaluation of the rule group took place.
func (g *Group) GetLastEvaluation() time.Time {
g.mtx.Lock()
defer g.mtx.Unlock()
return g.lastEvaluation
}
// setLastEvaluation updates evaluationTimestamp to the timestamp of when the rule group was last evaluated.
func (g *Group) setLastEvaluation(ts time.Time) {
g.metrics.GroupLastEvalTime.WithLabelValues(GroupKey(g.file, g.name)).Set(float64(ts.UnixNano()) / 1e9)
g.mtx.Lock()
defer g.mtx.Unlock()
g.lastEvaluation = ts
}
// GetLastEvalTimestamp returns the timestamp of the last evaluation.
func (g *Group) GetLastEvalTimestamp() time.Time {
g.mtx.Lock()
defer g.mtx.Unlock()
return g.lastEvalTimestamp
}
// setLastEvalTimestamp updates lastEvalTimestamp to the timestamp of the last evaluation.
func (g *Group) setLastEvalTimestamp(ts time.Time) {
g.mtx.Lock()
defer g.mtx.Unlock()
g.lastEvalTimestamp = ts
}
// EvalTimestamp returns the immediately preceding consistently slotted evaluation time.
func (g *Group) EvalTimestamp(startTime int64) time.Time {
var (
offset = int64(g.hash() % uint64(g.interval))
// This group's evaluation times differ from the perfect time intervals by `offset` nanoseconds.
// But we can only use `% interval` to align with the interval. And `% interval` will always
// align with the perfect time intervals, instead of this group's. Because of this we add
// `offset` _after_ aligning with the perfect time interval.
//
// There can be cases where adding `offset` to the perfect evaluation time can yield a
// timestamp in the future, which is not what EvalTimestamp should do.
// So we subtract one `offset` to make sure that `now - (now % interval) + offset` gives an
// evaluation time in the past.
adjNow = startTime - offset
// Adjust to perfect evaluation intervals.
base = adjNow - (adjNow % int64(g.interval))
// Add one offset to randomize the evaluation times of this group.
next = base + offset
)
return time.Unix(0, next).UTC()
}
func nameAndLabels(rule Rule) string {
return rule.Name() + rule.Labels().String()
}
// CopyState copies the alerting rule and staleness related state from the given group.
//
// Rules are matched based on their name and labels. If there are duplicates, the
// first is matched with the first, second with the second etc.
func (g *Group) CopyState(from *Group) {
g.evaluationTime = from.evaluationTime
g.lastEvaluation = from.lastEvaluation
ruleMap := make(map[string][]int, len(from.rules))
for fi, fromRule := range from.rules {
nameAndLabels := nameAndLabels(fromRule)
l := ruleMap[nameAndLabels]
ruleMap[nameAndLabels] = append(l, fi)
}
for i, rule := range g.rules {
nameAndLabels := nameAndLabels(rule)
indexes := ruleMap[nameAndLabels]
if len(indexes) == 0 {
continue
}
fi := indexes[0]
g.seriesInPreviousEval[i] = from.seriesInPreviousEval[fi]
ruleMap[nameAndLabels] = indexes[1:]
ar, ok := rule.(*AlertingRule)
if !ok {
continue
}
far, ok := from.rules[fi].(*AlertingRule)
if !ok {
continue
}
for fp, a := range far.active {
ar.active[fp] = a
}
}
// Handle deleted and unmatched duplicate rules.
g.staleSeries = from.staleSeries
for fi, fromRule := range from.rules {
nameAndLabels := nameAndLabels(fromRule)
l := ruleMap[nameAndLabels]
if len(l) != 0 {
for _, series := range from.seriesInPreviousEval[fi] {
g.staleSeries = append(g.staleSeries, series)
}
}
}
}
// Eval runs a single evaluation cycle in which all rules are evaluated sequentially.
// Rules can be evaluated concurrently if the `concurrent-rule-eval` feature flag is enabled.
func (g *Group) Eval(ctx context.Context, ts time.Time) {
var (
samplesTotal atomic.Float64
wg sync.WaitGroup
)
for i, rule := range g.rules {
select {
case <-g.done:
return
default:
}
eval := func(i int, rule Rule, cleanup func()) {
if cleanup != nil {
defer cleanup()
}
logger := log.WithPrefix(g.logger, "name", rule.Name(), "index", i)
ctx, sp := otel.Tracer("").Start(ctx, "rule")
sp.SetAttributes(attribute.String("name", rule.Name()))
defer func(t time.Time) {
sp.End()
since := time.Since(t)
g.metrics.EvalDuration.Observe(since.Seconds())
rule.SetEvaluationDuration(since)
rule.SetEvaluationTimestamp(t)
}(time.Now())
if sp.SpanContext().IsSampled() && sp.SpanContext().HasTraceID() {
logger = log.WithPrefix(logger, "traceID", sp.SpanContext().TraceID())
}
g.metrics.EvalTotal.WithLabelValues(GroupKey(g.File(), g.Name())).Inc()
vector, err := rule.Eval(ctx, ts, g.opts.QueryFunc, g.opts.ExternalURL, g.Limit())
if err != nil {
rule.SetHealth(HealthBad)
rule.SetLastError(err)
sp.SetStatus(codes.Error, err.Error())
g.metrics.EvalFailures.WithLabelValues(GroupKey(g.File(), g.Name())).Inc()
// Canceled queries are intentional termination of queries. This normally
// happens on shutdown and thus we skip logging of any errors here.
var eqc promql.ErrQueryCanceled
if !errors.As(err, &eqc) {
level.Warn(logger).Log("msg", "Evaluating rule failed", "rule", rule, "err", err)
}
return
}
rule.SetHealth(HealthGood)
rule.SetLastError(nil)
samplesTotal.Add(float64(len(vector)))
if ar, ok := rule.(*AlertingRule); ok {
ar.sendAlerts(ctx, ts, g.opts.ResendDelay, g.interval, g.opts.NotifyFunc)
}
var (
numOutOfOrder = 0
numTooOld = 0
numDuplicates = 0
)
app := g.opts.Appendable.Appender(ctx)
seriesReturned := make(map[string]labels.Labels, len(g.seriesInPreviousEval[i]))
defer func() {
if err := app.Commit(); err != nil {
rule.SetHealth(HealthBad)
rule.SetLastError(err)
sp.SetStatus(codes.Error, err.Error())
g.metrics.EvalFailures.WithLabelValues(GroupKey(g.File(), g.Name())).Inc()
level.Warn(logger).Log("msg", "Rule sample appending failed", "err", err)
return
}
g.seriesInPreviousEval[i] = seriesReturned
}()
for _, s := range vector {
if s.H != nil {
_, err = app.AppendHistogram(0, s.Metric, s.T, nil, s.H)
} else {
_, err = app.Append(0, s.Metric, s.T, s.F)
}
if err != nil {
rule.SetHealth(HealthBad)
rule.SetLastError(err)
sp.SetStatus(codes.Error, err.Error())
unwrappedErr := errors.Unwrap(err)
if unwrappedErr == nil {
unwrappedErr = err
}
switch {
case errors.Is(unwrappedErr, storage.ErrOutOfOrderSample):
numOutOfOrder++
level.Debug(logger).Log("msg", "Rule evaluation result discarded", "err", err, "sample", s)
case errors.Is(unwrappedErr, storage.ErrTooOldSample):
numTooOld++
level.Debug(logger).Log("msg", "Rule evaluation result discarded", "err", err, "sample", s)
case errors.Is(unwrappedErr, storage.ErrDuplicateSampleForTimestamp):
numDuplicates++
level.Debug(logger).Log("msg", "Rule evaluation result discarded", "err", err, "sample", s)
default:
level.Warn(logger).Log("msg", "Rule evaluation result discarded", "err", err, "sample", s)
}
} else {
buf := [1024]byte{}
seriesReturned[string(s.Metric.Bytes(buf[:]))] = s.Metric
}
}
if numOutOfOrder > 0 {
level.Warn(logger).Log("msg", "Error on ingesting out-of-order result from rule evaluation", "numDropped", numOutOfOrder)
}
if numTooOld > 0 {
level.Warn(logger).Log("msg", "Error on ingesting too old result from rule evaluation", "numDropped", numTooOld)
}
if numDuplicates > 0 {
level.Warn(logger).Log("msg", "Error on ingesting results from rule evaluation with different value but same timestamp", "numDropped", numDuplicates)
}
for metric, lset := range g.seriesInPreviousEval[i] {
if _, ok := seriesReturned[metric]; !ok {
// Series no longer exposed, mark it stale.
_, err = app.Append(0, lset, timestamp.FromTime(ts), math.Float64frombits(value.StaleNaN))
unwrappedErr := errors.Unwrap(err)
if unwrappedErr == nil {
unwrappedErr = err
}
switch {
case unwrappedErr == nil:
case errors.Is(unwrappedErr, storage.ErrOutOfOrderSample),
errors.Is(unwrappedErr, storage.ErrTooOldSample),
errors.Is(unwrappedErr, storage.ErrDuplicateSampleForTimestamp):
// Do not count these in logging, as this is expected if series
// is exposed from a different rule.
default:
level.Warn(logger).Log("msg", "Adding stale sample failed", "sample", lset.String(), "err", err)
}
}
}
}
// If the rule has no dependencies, it can run concurrently because no other rules in this group depend on its output.
// Try run concurrently if there are slots available.
if ctrl := g.concurrencyController; isRuleEligibleForConcurrentExecution(rule) && ctrl.Allow() {
wg.Add(1)
go eval(i, rule, func() {
wg.Done()
ctrl.Done()
})
} else {
eval(i, rule, nil)
}
}
wg.Wait()
g.metrics.GroupSamples.WithLabelValues(GroupKey(g.File(), g.Name())).Set(samplesTotal.Load())
g.cleanupStaleSeries(ctx, ts)
}
func (g *Group) cleanupStaleSeries(ctx context.Context, ts time.Time) {
if len(g.staleSeries) == 0 {
return
}
app := g.opts.Appendable.Appender(ctx)
for _, s := range g.staleSeries {
// Rule that produced series no longer configured, mark it stale.
_, err := app.Append(0, s, timestamp.FromTime(ts), math.Float64frombits(value.StaleNaN))
unwrappedErr := errors.Unwrap(err)
if unwrappedErr == nil {
unwrappedErr = err
}
switch {
case unwrappedErr == nil:
case errors.Is(unwrappedErr, storage.ErrOutOfOrderSample),
errors.Is(unwrappedErr, storage.ErrTooOldSample),
errors.Is(unwrappedErr, storage.ErrDuplicateSampleForTimestamp):
// Do not count these in logging, as this is expected if series
// is exposed from a different rule.
default:
level.Warn(g.logger).Log("msg", "Adding stale sample for previous configuration failed", "sample", s, "err", err)
}
}
if err := app.Commit(); err != nil {
level.Warn(g.logger).Log("msg", "Stale sample appending for previous configuration failed", "err", err)
} else {
g.staleSeries = nil
}
}
// RestoreForState restores the 'for' state of the alerts
// by looking up last ActiveAt from storage.
func (g *Group) RestoreForState(ts time.Time) {
maxtMS := int64(model.TimeFromUnixNano(ts.UnixNano()))
// We allow restoration only if alerts were active before after certain time.
mint := ts.Add(-g.opts.OutageTolerance)
mintMS := int64(model.TimeFromUnixNano(mint.UnixNano()))
q, err := g.opts.Queryable.Querier(mintMS, maxtMS)
if err != nil {
level.Error(g.logger).Log("msg", "Failed to get Querier", "err", err)
return
}
defer func() {
if err := q.Close(); err != nil {
level.Error(g.logger).Log("msg", "Failed to close Querier", "err", err)
}
}()
for _, rule := range g.Rules() {
alertRule, ok := rule.(*AlertingRule)
if !ok {
continue
}
alertHoldDuration := alertRule.HoldDuration()
if alertHoldDuration < g.opts.ForGracePeriod {
// If alertHoldDuration is already less than grace period, we would not
// like to make it wait for `g.opts.ForGracePeriod` time before firing.
// Hence we skip restoration, which will make it wait for alertHoldDuration.
alertRule.SetRestored(true)
continue
}
alertRule.ForEachActiveAlert(func(a *Alert) {
var s storage.Series
s, err := alertRule.QueryforStateSeries(g.opts.Context, a, q)
if err != nil {
// Querier Warnings are ignored. We do not care unless we have an error.
level.Error(g.logger).Log(
"msg", "Failed to restore 'for' state",
labels.AlertName, alertRule.Name(),
"stage", "Select",
"err", err,
)
return
}
if s == nil {
return
}
// Series found for the 'for' state.
var t int64
var v float64
it := s.Iterator(nil)
for it.Next() == chunkenc.ValFloat {
t, v = it.At()
}
if it.Err() != nil {
level.Error(g.logger).Log("msg", "Failed to restore 'for' state",
labels.AlertName, alertRule.Name(), "stage", "Iterator", "err", it.Err())
return
}
if value.IsStaleNaN(v) { // Alert was not active.
return
}
downAt := time.Unix(t/1000, 0).UTC()
restoredActiveAt := time.Unix(int64(v), 0).UTC()
timeSpentPending := downAt.Sub(restoredActiveAt)
timeRemainingPending := alertHoldDuration - timeSpentPending
switch {
case timeRemainingPending <= 0:
// It means that alert was firing when prometheus went down.
// In the next Eval, the state of this alert will be set back to
// firing again if it's still firing in that Eval.
// Nothing to be done in this case.
case timeRemainingPending < g.opts.ForGracePeriod:
// (new) restoredActiveAt = (ts + m.opts.ForGracePeriod) - alertHoldDuration
// /* new firing time */ /* moving back by hold duration */
//
// Proof of correctness:
// firingTime = restoredActiveAt.Add(alertHoldDuration)
// = ts + m.opts.ForGracePeriod - alertHoldDuration + alertHoldDuration
// = ts + m.opts.ForGracePeriod
//
// Time remaining to fire = firingTime.Sub(ts)
// = (ts + m.opts.ForGracePeriod) - ts
// = m.opts.ForGracePeriod
restoredActiveAt = ts.Add(g.opts.ForGracePeriod).Add(-alertHoldDuration)
default:
// By shifting ActiveAt to the future (ActiveAt + some_duration),
// the total pending time from the original ActiveAt
// would be `alertHoldDuration + some_duration`.
// Here, some_duration = downDuration.
downDuration := ts.Sub(downAt)
restoredActiveAt = restoredActiveAt.Add(downDuration)
}
a.ActiveAt = restoredActiveAt
level.Debug(g.logger).Log("msg", "'for' state restored",
labels.AlertName, alertRule.Name(), "restored_time", a.ActiveAt.Format(time.RFC850),
"labels", a.Labels.String())
})
alertRule.SetRestored(true)
}
}
// Equals return if two groups are the same.
func (g *Group) Equals(ng *Group) bool {
if g.name != ng.name {
return false
}
if g.file != ng.file {
return false
}
if g.interval != ng.interval {
return false
}
if g.limit != ng.limit {
return false
}
if len(g.rules) != len(ng.rules) {
return false
}
for i, gr := range g.rules {
if gr.String() != ng.rules[i].String() {
return false
}
}
return true
}
// GroupKey group names need not be unique across filenames.
func GroupKey(file, name string) string {
return file + ";" + name
}
// Constants for instrumentation.
const namespace = "prometheus"
// Metrics for rule evaluation.
type Metrics struct {
EvalDuration prometheus.Summary
IterationDuration prometheus.Summary
IterationsMissed *prometheus.CounterVec
IterationsScheduled *prometheus.CounterVec
EvalTotal *prometheus.CounterVec
EvalFailures *prometheus.CounterVec
GroupInterval *prometheus.GaugeVec
GroupLastEvalTime *prometheus.GaugeVec
GroupLastDuration *prometheus.GaugeVec
GroupRules *prometheus.GaugeVec
GroupSamples *prometheus.GaugeVec
}
// NewGroupMetrics creates a new instance of Metrics and registers it with the provided registerer,
// if not nil.
func NewGroupMetrics(reg prometheus.Registerer) *Metrics {
m := &Metrics{
EvalDuration: prometheus.NewSummary(
prometheus.SummaryOpts{
Namespace: namespace,
Name: "rule_evaluation_duration_seconds",
Help: "The duration for a rule to execute.",
Objectives: map[float64]float64{0.5: 0.05, 0.9: 0.01, 0.99: 0.001},
}),
IterationDuration: prometheus.NewSummary(prometheus.SummaryOpts{
Namespace: namespace,
Name: "rule_group_duration_seconds",
Help: "The duration of rule group evaluations.",
Objectives: map[float64]float64{0.01: 0.001, 0.05: 0.005, 0.5: 0.05, 0.90: 0.01, 0.99: 0.001},
}),
IterationsMissed: prometheus.NewCounterVec(
prometheus.CounterOpts{
Namespace: namespace,
Name: "rule_group_iterations_missed_total",
Help: "The total number of rule group evaluations missed due to slow rule group evaluation.",
},
[]string{"rule_group"},
),
IterationsScheduled: prometheus.NewCounterVec(
prometheus.CounterOpts{
Namespace: namespace,
Name: "rule_group_iterations_total",
Help: "The total number of scheduled rule group evaluations, whether executed or missed.",
},
[]string{"rule_group"},
),
EvalTotal: prometheus.NewCounterVec(
prometheus.CounterOpts{
Namespace: namespace,
Name: "rule_evaluations_total",
Help: "The total number of rule evaluations.",
},
[]string{"rule_group"},
),
EvalFailures: prometheus.NewCounterVec(
prometheus.CounterOpts{
Namespace: namespace,
Name: "rule_evaluation_failures_total",
Help: "The total number of rule evaluation failures.",
},
[]string{"rule_group"},
),
GroupInterval: prometheus.NewGaugeVec(
prometheus.GaugeOpts{
Namespace: namespace,
Name: "rule_group_interval_seconds",
Help: "The interval of a rule group.",
},
[]string{"rule_group"},
),
GroupLastEvalTime: prometheus.NewGaugeVec(
prometheus.GaugeOpts{
Namespace: namespace,
Name: "rule_group_last_evaluation_timestamp_seconds",
Help: "The timestamp of the last rule group evaluation in seconds.",
},
[]string{"rule_group"},
),
GroupLastDuration: prometheus.NewGaugeVec(
prometheus.GaugeOpts{
Namespace: namespace,
Name: "rule_group_last_duration_seconds",
Help: "The duration of the last rule group evaluation.",
},
[]string{"rule_group"},
),
GroupRules: prometheus.NewGaugeVec(
prometheus.GaugeOpts{
Namespace: namespace,
Name: "rule_group_rules",
Help: "The number of rules.",
},
[]string{"rule_group"},
),
GroupSamples: prometheus.NewGaugeVec(
prometheus.GaugeOpts{
Namespace: namespace,
Name: "rule_group_last_evaluation_samples",
Help: "The number of samples returned during the last rule group evaluation.",
},
[]string{"rule_group"},
),
}
if reg != nil {
reg.MustRegister(
m.EvalDuration,
m.IterationDuration,
m.IterationsMissed,
m.IterationsScheduled,
m.EvalTotal,
m.EvalFailures,
m.GroupInterval,
m.GroupLastEvalTime,
m.GroupLastDuration,
m.GroupRules,
m.GroupSamples,
)
}
return m
}
// dependencyMap is a data-structure which contains the relationships between rules within a group.
// It is used to describe the dependency associations between rules in a group whereby one rule uses the
// output metric produced by another rule in its expression (i.e. as its "input").
type dependencyMap map[Rule][]Rule
// dependents returns the count of rules which use the output of the given rule as one of their inputs.
func (m dependencyMap) dependents(r Rule) int {
return len(m[r])
}
// dependencies returns the count of rules on which the given rule is dependent for input.
func (m dependencyMap) dependencies(r Rule) int {
if len(m) == 0 {
return 0
}
var count int
for _, children := range m {
for _, child := range children {
if child == r {
count++
}
}
}
return count
}
// isIndependent determines whether the given rule is not dependent on another rule for its input, nor is any other rule
// dependent on its output.
func (m dependencyMap) isIndependent(r Rule) bool {
if m == nil {
return false
}
return m.dependents(r)+m.dependencies(r) == 0
}
// buildDependencyMap builds a data-structure which contains the relationships between rules within a group.
//
// Alert rules, by definition, cannot have any dependents - but they can have dependencies. Any recording rule on whose
// output an Alert rule depends will not be able to run concurrently.
//
// There is a class of rule expressions which are considered "indeterminate", because either relationships cannot be
// inferred, or concurrent evaluation of rules depending on these series would produce undefined/unexpected behaviour:
// - wildcard queriers like {cluster="prod1"} which would match every series with that label selector
// - any "meta" series (series produced by Prometheus itself) like ALERTS, ALERTS_FOR_STATE
//
// Rules which are independent can run concurrently with no side-effects.
func buildDependencyMap(rules []Rule) dependencyMap {
dependencies := make(dependencyMap)
if len(rules) <= 1 {
// No relationships if group has 1 or fewer rules.
return dependencies
}
inputs := make(map[string][]Rule, len(rules))
outputs := make(map[string][]Rule, len(rules))
var indeterminate bool
for _, rule := range rules {
if indeterminate {
break
}
name := rule.Name()
outputs[name] = append(outputs[name], rule)
parser.Inspect(rule.Query(), func(node parser.Node, path []parser.Node) error {
if n, ok := node.(*parser.VectorSelector); ok {
// A wildcard metric expression means we cannot reliably determine if this rule depends on any other,
// which means we cannot safely run any rules concurrently.
if n.Name == "" && len(n.LabelMatchers) > 0 {
indeterminate = true
return nil
}
// Rules which depend on "meta-metrics" like ALERTS and ALERTS_FOR_STATE will have undefined behaviour
// if they run concurrently.
if n.Name == alertMetricName || n.Name == alertForStateMetricName {
indeterminate = true
return nil
}
inputs[n.Name] = append(inputs[n.Name], rule)
}
return nil
})
}
if indeterminate {
return nil
}
for output, outRules := range outputs {
for _, outRule := range outRules {
if inRules, found := inputs[output]; found && len(inRules) > 0 {
dependencies[outRule] = append(dependencies[outRule], inRules...)
}
}
}
return dependencies
}
func isRuleEligibleForConcurrentExecution(rule Rule) bool {
return rule.NoDependentRules() && rule.NoDependencyRules()
}