include group first evaluation into interval ticker

app/vmalert/rule/alerting.go

@@ -789,16 +789,7 @@ func firingAlertStaleTimeSeries(ls map[string]string, timestamp int64) []prompb.
 
 // restore restores the value of ActiveAt field for active alerts,
 // based on previously written time series `alertForStateMetricName`.
-// Only rules with For > 0 can be restored.
 func (ar *AlertingRule) restore(ctx context.Context, q datasource.Querier, ts time.Time, lookback time.Duration) error {
-	if ar.For < 1 {
-		return nil
-	}
-
-	if len(ar.alerts) < 1 {
-		return nil
-	}
-
 	nameStr := fmt.Sprintf("%s=%q", alertNameLabel, ar.Name)
 	if !*disableAlertGroupLabel {
 		nameStr = fmt.Sprintf("%s=%q,%s=%q", alertGroupNameLabel, ar.GroupName, alertNameLabel, ar.Name)

app/vmalert/rule/group.go

@@ -8,6 +8,7 @@ import (
 	"hash/fnv"
 	"maps"
 	"net/url"
+	"os"
 	"sync"
 	"time"
 
@@ -213,6 +214,7 @@ func (g *Group) CreateID() uint64 {
 // restore restores alerts state for group rules
 func (g *Group) restore(ctx context.Context, qb datasource.QuerierBuilder, ts time.Time, lookback time.Duration) error {
 	for _, rule := range g.Rules {
+		// Only alerting rule with for > 0 and has active alerts from the first evaluation can be restored
 		ar, ok := rule.(*AlertingRule)
 		if !ok {
 			continue
@@ -220,6 +222,9 @@ func (g *Group) restore(ctx context.Context, qb datasource.QuerierBuilder, ts ti
 		if ar.For < 1 {
 			continue
 		}
+		if len(ar.alerts) < 1 {
+			return nil
+		}
 		q := qb.BuildWithParams(datasource.QuerierParams{
 			EvaluationInterval: g.Interval,
 			QueryParams:        g.Params,
@@ -333,6 +338,11 @@ func (g *Group) Init() {
 // Start starts group's evaluation
 func (g *Group) Start(ctx context.Context, rw remotewrite.RWClient, rr datasource.QuerierBuilder) {
 	defer func() { close(g.finishedCh) }()
+	e := &executor{
+		Rw:              rw,
+		notifierHeaders: g.NotifierHeaders,
+	}
+
 	evalTS := time.Now()
 	// sleep random duration to spread group rules evaluation
 	// over maxStartDelay to reduce the load on datasource.
@@ -367,11 +377,6 @@ func (g *Group) Start(ctx context.Context, rw remotewrite.RWClient, rr datasourc
 		evalTS = evalTS.Add(sleepBeforeStart)
 	}
 
-	e := &executor{
-		Rw:              rw,
-		notifierHeaders: g.NotifierHeaders,
-	}
-
 	g.infof("started")
 
 	eval := func(ctx context.Context, ts time.Time) time.Time {
@@ -381,7 +386,9 @@ func (g *Group) Start(ctx context.Context, rw remotewrite.RWClient, rr datasourc
 
 		if len(g.Rules) < 1 {
 			g.metrics.iterationDuration.UpdateDuration(start)
+			g.mu.Lock()
 			g.LastEvaluation = start
+			g.mu.Unlock()
 			return ts
 		}
 
@@ -395,7 +402,32 @@ func (g *Group) Start(ctx context.Context, rw remotewrite.RWClient, rr datasourc
 			}
 		}
 		g.metrics.iterationDuration.UpdateDuration(start)
+		g.mu.Lock()
 		g.LastEvaluation = start
+		g.mu.Unlock()
+		if g.EvalOffset != nil && e.Rw != nil {
+			hostname, err := os.Hostname()
+			if err != nil {
+				hostname = "unknown"
+			}
+			labels := map[string]string{
+				"__name__": "vmalert_eval_timestamp",
+				"host":     hostname,
+				"group":    g.Name,
+				"file":     g.File,
+			}
+			var ls []prompb.Label
+			for k, v := range labels {
+				ls = append(ls, prompb.Label{
+					Name:  k,
+					Value: v,
+				})
+			}
+			ts := newTimeSeries([]float64{float64(ts.Unix())}, []int64{start.Unix()}, ls)
+			if err := e.Rw.Push(ts); err != nil {
+				logger.Errorf("group %q: failed to push evaluation timestamp: %s", g.Name, err)
+			}
+		}
 		return ts
 	}
 
@@ -405,11 +437,11 @@ func (g *Group) Start(ctx context.Context, rw remotewrite.RWClient, rr datasourc
 	g.mu.Unlock()
 	defer g.evalCancel()
 
-	realEvalTS := eval(evalCtx, evalTS)
-
 	t := time.NewTicker(g.Interval)
 	defer t.Stop()
 
+	realEvalTS := eval(evalCtx, evalTS)
+
 	// restore the rules state after the first evaluation
 	// so only active alerts can be restored.
 	if rr != nil {