Check that rules don't contain metrics with the same labelset (#6469)

Closes #5529

Signed-off-by: Julien Pivotto <roidelapluie@inuits.eu>

rules/alerting.go

@@ -311,6 +311,7 @@ func (r *AlertingRule) Eval(ctx context.Context, ts time.Time, query QueryFunc,
 	resultFPs := map[uint64]struct{}{}
 
 	var vec promql.Vector
+	var alerts = make(map[uint64]*Alert, len(res))
 	for _, smpl := range res {
 		// Provide the alert information to the template.
 		l := make(map[string]string, len(smpl.Metric))
@@ -361,15 +362,16 @@ func (r *AlertingRule) Eval(ctx context.Context, ts time.Time, query QueryFunc,
 		h := lbs.Hash()
 		resultFPs[h] = struct{}{}
 
-		// Check whether we already have alerting state for the identifying label set.
-		// Update the last value and annotations if so, create a new alert entry otherwise.
-		if alert, ok := r.active[h]; ok && alert.State != StateInactive {
-			alert.Value = smpl.V
-			alert.Annotations = annotations
-			continue
+		if _, ok := alerts[h]; ok {
+			err = fmt.Errorf("vector contains metrics with the same labelset after applying alert labels")
+			// We have already acquired the lock above hence using SetHealth and
+			// SetLastError will deadlock.
+			r.health = HealthBad
+			r.lastError = err
+			return nil, err
 		}
 
-		r.active[h] = &Alert{
+		alerts[h] = &Alert{
 			Labels:      lbs,
 			Annotations: annotations,
 			ActiveAt:    ts,
@@ -378,6 +380,18 @@ func (r *AlertingRule) Eval(ctx context.Context, ts time.Time, query QueryFunc,
 		}
 	}
 
+	for h, a := range alerts {
+		// Check whether we already have alerting state for the identifying label set.
+		// Update the last value and annotations if so, create a new alert entry otherwise.
+		if alert, ok := r.active[h]; ok && alert.State != StateInactive {
+			alert.Value = a.Value
+			alert.Annotations = a.Annotations
+			continue
+		}
+
+		r.active[h] = a
+	}
+
 	// Check if any pending alerts should be removed or fire now. Write out alert timeseries.
 	for fp, a := range r.active {
 		if _, ok := resultFPs[fp]; !ok {

rules/alerting_test.go

@@ -14,6 +14,8 @@
 package rules
 
 import (
+	"context"
+	"fmt"
 	"testing"
 	"time"
 
@@ -21,6 +23,7 @@ import (
 	"github.com/prometheus/prometheus/pkg/labels"
 	"github.com/prometheus/prometheus/pkg/timestamp"
 	"github.com/prometheus/prometheus/promql"
+	"github.com/prometheus/prometheus/util/teststorage"
 	"github.com/prometheus/prometheus/util/testutil"
 )
 
@@ -289,3 +292,37 @@ func TestAlertingRuleEmptyLabelFromTemplate(t *testing.T) {
 	}
 	testutil.Equals(t, result, filteredRes)
 }
+
+func TestAlertingRuleDuplicate(t *testing.T) {
+	storage := teststorage.New(t)
+	defer storage.Close()
+
+	opts := promql.EngineOpts{
+		Logger:        nil,
+		Reg:           nil,
+		MaxConcurrent: 10,
+		MaxSamples:    10,
+		Timeout:       10 * time.Second,
+	}
+
+	engine := promql.NewEngine(opts)
+	ctx, cancelCtx := context.WithCancel(context.Background())
+	defer cancelCtx()
+
+	now := time.Now()
+
+	expr, _ := promql.ParseExpr(`vector(0) or label_replace(vector(0),"test","x","","")`)
+	rule := NewAlertingRule(
+		"foo",
+		expr,
+		time.Minute,
+		labels.FromStrings("test", "test"),
+		nil,
+		nil,
+		true, log.NewNopLogger(),
+	)
+	_, err := rule.Eval(ctx, now, EngineQueryFunc(engine, storage), nil)
+	testutil.NotOk(t, err)
+	e := fmt.Errorf("vector contains metrics with the same labelset after applying alert labels")
+	testutil.ErrorEqual(t, e, err)
+}

rules/recording.go

@@ -93,6 +93,16 @@ func (rule *RecordingRule) Eval(ctx context.Context, ts time.Time, query QueryFu
 
 		sample.Metric = lb.Labels()
 	}
+
+	// Check that the rule does not produce identical metrics after applying
+	// labels.
+	if vector.ContainsSameLabelset() {
+		err = fmt.Errorf("vector contains metrics with the same labelset after applying rule labels")
+		rule.SetHealth(HealthBad)
+		rule.SetLastError(err)
+		return nil, err
+	}
+
 	rule.SetHealth(HealthGood)
 	rule.SetLastError(err)
 	return vector, nil

rules/recording_test.go

@@ -15,6 +15,7 @@ package rules
 
 import (
 	"context"
+	"fmt"
 	"testing"
 	"time"
 
@@ -91,3 +92,30 @@ labels:
 	got := rule.HTMLSnippet("/test/prefix")
 	testutil.Assert(t, want == got, "incorrect HTML snippet; want:\n\n%s\n\ngot:\n\n%s", want, got)
 }
+
+// TestRuleEvalDuplicate tests for duplicate labels in recorded metrics, see #5529.
+func TestRuleEvalDuplicate(t *testing.T) {
+	storage := teststorage.New(t)
+	defer storage.Close()
+
+	opts := promql.EngineOpts{
+		Logger:        nil,
+		Reg:           nil,
+		MaxConcurrent: 10,
+		MaxSamples:    10,
+		Timeout:       10 * time.Second,
+	}
+
+	engine := promql.NewEngine(opts)
+	ctx, cancelCtx := context.WithCancel(context.Background())
+	defer cancelCtx()
+
+	now := time.Now()
+
+	expr, _ := promql.ParseExpr(`vector(0) or label_replace(vector(0),"test","x","","")`)
+	rule := NewRecordingRule("foo", expr, labels.FromStrings("test", "test"))
+	_, err := rule.Eval(ctx, now, EngineQueryFunc(engine, storage), nil)
+	testutil.NotOk(t, err)
+	e := fmt.Errorf("vector contains metrics with the same labelset after applying rule labels")
+	testutil.ErrorEqual(t, e, err)
+}