Fix silence tests

This commit fixes the silence tests, using the exact same tests
in prometheus/alertmanager to avoid regressions due to modules,
but using the New function in pkg/alertmanager/alertmanager.go
to ensure the correct limits are set.

It bumps go.mod to commit 2410524 which is a no-op as Mimir
does not vendor tests, but its meant to indicate we are using
the fix from prometheus/alertmanager#3866.

go.mod

@@ -284,4 +284,4 @@ replace github.com/opentracing-contrib/go-stdlib => github.com/grafana/opentraci
 replace github.com/opentracing-contrib/go-grpc => github.com/charleskorn/go-grpc v0.0.0-20231024023642-e9298576254f
 
 // Replacing prometheus/alertmanager with our fork.
-replace github.com/prometheus/alertmanager => github.com/grafana/prometheus-alertmanager v0.25.1-0.20240603081606-9f1bbb0feb0c
+replace github.com/prometheus/alertmanager => github.com/grafana/prometheus-alertmanager v0.25.1-0.20240605140724-241052410551

go.sum

@@ -521,8 +521,8 @@ github.com/grafana/mimir-prometheus v0.0.0-20240515135245-e5b85c151ba8 h1:XmqfG3
 github.com/grafana/mimir-prometheus v0.0.0-20240515135245-e5b85c151ba8/go.mod h1:ZlD3SoAHSwXK5VGLHv78Jh5kOpgSLaQAzt9gxq76fLM=
 github.com/grafana/opentracing-contrib-go-stdlib v0.0.0-20230509071955-f410e79da956 h1:em1oddjXL8c1tL0iFdtVtPloq2hRPen2MJQKoAWpxu0=
 github.com/grafana/opentracing-contrib-go-stdlib v0.0.0-20230509071955-f410e79da956/go.mod h1:qtI1ogk+2JhVPIXVc6q+NHziSmy2W5GbdQZFUHADCBU=
-github.com/grafana/prometheus-alertmanager v0.25.1-0.20240603081606-9f1bbb0feb0c h1:Zgf0KrZy6of/6MQTRvzCVvKni/wWxEMWnipeqbo+0ek=
-github.com/grafana/prometheus-alertmanager v0.25.1-0.20240603081606-9f1bbb0feb0c/go.mod h1:01sXtHoRwI8W324IPAzuxDFOmALqYLCOhvSC2fUHWXc=
+github.com/grafana/prometheus-alertmanager v0.25.1-0.20240605140724-241052410551 h1:nj+Z280xVVSxeW9bbgEs2gxd//gRIwCxQFuSv4oh5MQ=
+github.com/grafana/prometheus-alertmanager v0.25.1-0.20240605140724-241052410551/go.mod h1:01sXtHoRwI8W324IPAzuxDFOmALqYLCOhvSC2fUHWXc=
 github.com/grafana/pyroscope-go/godeltaprof v0.1.6 h1:nEdZ8louGAplSvIJi1HVp7kWvFvdiiYg3COLlTwJiFo=
 github.com/grafana/pyroscope-go/godeltaprof v0.1.6/go.mod h1:Tk376Nbldo4Cha9RgiU7ik8WKFkNpfds98aUzS8omLE=
 github.com/grafana/regexp v0.0.0-20240531075221-3685f1377d7b h1:oMAq12GxTpwo9jxbnG/M4F/HdpwbibTaVoxNA0NZprY=

pkg/alertmanager/alertmanager_test.go

@@ -326,9 +326,7 @@ func testLimiter(t *testing.T, limits Limits, ops []callbackOp) {
 }
 
 func TestSilenceLimits(t *testing.T) {
-	t.Skip()
-
-	user := "test"
+	user := "foo"
 
 	r := prometheus.NewPedanticRegistry()
 	am, err := New(&Config{
@@ -345,13 +343,14 @@ func TestSilenceLimits(t *testing.T) {
 		Store:             prepareInMemoryAlertStore(),
 		Replicator:        &stubReplicator{},
 		ReplicationFactor: 1,
-		// Set the interval to 1s as this test can trigger multiple broadcasts
-		// creating and expiring silences.
-		PersisterConfig: PersisterConfig{Interval: time.Second},
+		PersisterConfig:   PersisterConfig{Interval: time.Hour},
 	}, r)
 	require.NoError(t, err)
 	defer am.StopAndWait()
 
+	// Override SetBroadcast as we just want to test limits.
+	am.silences.SetBroadcast(func(_ []byte) {})
+
 	// Insert sil1 should succeed without error.
 	sil1 := &silencepb.Silence{
 		Matchers: []*silencepb.Matcher{{Name: "a", Pattern: "b"}},
@@ -373,8 +372,13 @@ func TestSilenceLimits(t *testing.T) {
 	require.EqualError(t, err, "exceeded maximum number of silences: 1 (limit: 1)")
 	require.Equal(t, "", id2)
 
-	// Expire sil1. This should allow sil2 to be inserted.
+	// Expire sil1 and run the GC. This should allow sil2 to be
+	// inserted.
 	require.NoError(t, am.silences.Expire(id1))
+	n, err := am.silences.GC()
+	require.NoError(t, err)
+	require.Equal(t, 1, n)
+
 	id2, err = am.silences.Set(sil2)
 	require.NoError(t, err)
 	require.NotEqual(t, "", id2)
@@ -385,6 +389,9 @@ func TestSilenceLimits(t *testing.T) {
 
 	// Expire sil2.
 	require.NoError(t, am.silences.Expire(id2))
+	n, err = am.silences.GC()
+	require.NoError(t, err)
+	require.Equal(t, 1, n)
 
 	// Insert sil3 should fail because it exceeds maximum size.
 	sil3 := &silencepb.Silence{