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rule.go
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rule.go
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package main
import (
"context"
"errors"
"fmt"
"hash/fnv"
"sort"
"strconv"
"sync"
"time"
"github.com/VictoriaMetrics/VictoriaMetrics/app/vmalert/datasource"
"github.com/VictoriaMetrics/VictoriaMetrics/app/vmalert/notifier"
"github.com/VictoriaMetrics/VictoriaMetrics/lib/metricsql"
"github.com/VictoriaMetrics/VictoriaMetrics/lib/prompbmarshal"
)
// Group grouping array of alert
type Group struct {
Name string
Rules []*Rule
}
// Rule is basic alert entity
type Rule struct {
Name string `yaml:"alert"`
Expr string `yaml:"expr"`
For time.Duration `yaml:"for"`
Labels map[string]string `yaml:"labels"`
Annotations map[string]string `yaml:"annotations"`
group *Group
// guard status fields
mu sync.RWMutex
// stores list of active alerts
alerts map[uint64]*notifier.Alert
// stores last moment of time Exec was called
lastExecTime time.Time
// stores last error that happened in Exec func
// resets on every successful Exec
// may be used as Health state
lastExecError error
}
// Validate validates rule
func (r *Rule) Validate() error {
if r.Name == "" {
return errors.New("rule name can not be empty")
}
if r.Expr == "" {
return fmt.Errorf("expression for rule %q can't be empty", r.Name)
}
if _, err := metricsql.Parse(r.Expr); err != nil {
return fmt.Errorf("invalid expression for rule %q: %w", r.Name, err)
}
return nil
}
// Exec executes Rule expression via the given Querier.
// Based on the Querier results Rule maintains notifier.Alerts
func (r *Rule) Exec(ctx context.Context, q datasource.Querier) error {
qMetrics, err := q.Query(ctx, r.Expr)
r.mu.Lock()
defer r.mu.Unlock()
r.lastExecError = err
r.lastExecTime = time.Now()
if err != nil {
return fmt.Errorf("failed to execute query %q: %s", r.Expr, err)
}
for h, a := range r.alerts {
// cleanup inactive alerts from previous Eval
if a.State == notifier.StateInactive {
delete(r.alerts, h)
}
}
updated := make(map[uint64]struct{})
// update list of active alerts
for _, m := range qMetrics {
h := hash(m)
updated[h] = struct{}{}
if _, ok := r.alerts[h]; ok {
continue
}
a, err := r.newAlert(m)
if err != nil {
r.lastExecError = err
return fmt.Errorf("failed to create alert: %s", err)
}
a.ID = h
a.State = notifier.StatePending
r.alerts[h] = a
}
for h, a := range r.alerts {
// if alert wasn't updated in this iteration
// means it is resolved already
if _, ok := updated[h]; !ok {
a.State = notifier.StateInactive
// set endTime to last execution time
// so it can be sent by notifier on next step
a.End = r.lastExecTime
continue
}
if a.State == notifier.StatePending && time.Since(a.Start) >= r.For {
a.State = notifier.StateFiring
alertsFired.Inc()
}
if a.State == notifier.StateFiring {
a.End = r.lastExecTime.Add(3 * *evaluationInterval)
}
}
return nil
}
// TODO: consider hashing algorithm in VM
func hash(m datasource.Metric) uint64 {
hash := fnv.New64a()
labels := m.Labels
sort.Slice(labels, func(i, j int) bool {
return labels[i].Name < labels[j].Name
})
for _, l := range labels {
hash.Write([]byte(l.Name))
hash.Write([]byte(l.Value))
hash.Write([]byte("\xff"))
}
return hash.Sum64()
}
func (r *Rule) newAlert(m datasource.Metric) (*notifier.Alert, error) {
a := ¬ifier.Alert{
Group: r.group.Name,
Name: r.Name,
Labels: map[string]string{},
Value: m.Value,
Start: time.Now(),
// TODO: support End time
}
// 1. use data labels
for _, l := range m.Labels {
a.Labels[l.Name] = l.Value
}
// 2. template rule labels with data labels
rLabels, err := a.ExecTemplate(r.Labels)
if err != nil {
return a, err
}
// 3. merge data labels and rule labels
// metric labels may be overridden by
// rule labels
for k, v := range rLabels {
a.Labels[k] = v
}
// 4. template merged labels
a.Labels, err = a.ExecTemplate(a.Labels)
if err != nil {
return a, err
}
a.Annotations, err = a.ExecTemplate(r.Annotations)
return a, err
}
// AlertAPI generates APIAlert object from alert by its id(hash)
func (r *Rule) AlertAPI(id uint64) *APIAlert {
r.mu.RLock()
defer r.mu.RUnlock()
a, ok := r.alerts[id]
if !ok {
return nil
}
return r.newAlertAPI(*a)
}
// AlertsAPI generates list of APIAlert objects from existing alerts
func (r *Rule) AlertsAPI() []*APIAlert {
var alerts []*APIAlert
r.mu.RLock()
for _, a := range r.alerts {
alerts = append(alerts, r.newAlertAPI(*a))
}
r.mu.RUnlock()
return alerts
}
func (r *Rule) newAlertAPI(a notifier.Alert) *APIAlert {
return &APIAlert{
ID: a.ID,
Name: a.Name,
Group: a.Group,
Expression: r.Expr,
Labels: a.Labels,
Annotations: a.Annotations,
State: a.State.String(),
ActiveAt: a.Start,
Value: strconv.FormatFloat(a.Value, 'e', -1, 64),
}
}
const (
// AlertMetricName is the metric name for synthetic alert timeseries.
alertMetricName = "ALERTS"
// AlertForStateMetricName is the metric name for 'for' state of alert.
alertForStateMetricName = "ALERTS_FOR_STATE"
// AlertNameLabel is the label name indicating the name of an alert.
alertNameLabel = "alertname"
// AlertStateLabel is the label name indicating the state of an alert.
alertStateLabel = "alertstate"
)
func (r *Rule) AlertToTimeSeries(a *notifier.Alert, timestamp time.Time) []prompbmarshal.TimeSeries {
var tss []prompbmarshal.TimeSeries
tss = append(tss, alertToTimeSeries(r.Name, a, timestamp))
if r.For > 0 {
tss = append(tss, alertForToTimeSeries(r.Name, a, timestamp))
}
return tss
}
func alertToTimeSeries(name string, a *notifier.Alert, timestamp time.Time) prompbmarshal.TimeSeries {
labels := make(map[string]string)
for k, v := range a.Labels {
labels[k] = v
}
labels["__name__"] = alertMetricName
labels[alertNameLabel] = name
labels[alertStateLabel] = a.State.String()
return newTimeSeries(1, labels, timestamp)
}
func alertForToTimeSeries(name string, a *notifier.Alert, timestamp time.Time) prompbmarshal.TimeSeries {
labels := make(map[string]string)
for k, v := range a.Labels {
labels[k] = v
}
labels["__name__"] = alertForStateMetricName
labels[alertNameLabel] = name
return newTimeSeries(float64(a.Start.Unix()), labels, timestamp)
}
func newTimeSeries(value float64, labels map[string]string, timestamp time.Time) prompbmarshal.TimeSeries {
ts := prompbmarshal.TimeSeries{}
ts.Samples = append(ts.Samples, prompbmarshal.Sample{
Value: value,
Timestamp: timestamp.UnixNano() / 1e6,
})
keys := make([]string, 0, len(labels))
for k := range labels {
keys = append(keys, k)
}
sort.Strings(keys)
for _, key := range keys {
ts.Labels = append(ts.Labels, prompbmarshal.Label{
Name: key,
Value: labels[key],
})
}
return ts
}