Keep readonly state when stopping lifecycler

CHANGELOG.md

@@ -25,6 +25,7 @@
 * [BUGFIX] Query Frontend: Fix panic caused by nil pointer dereference. #6609
 * [BUGFIX] Ingester: Add check to avoid query 5xx when closing tsdb. #6616
 * [BUGFIX] Querier: Fix panic when marshaling QueryResultRequest. #6601
+* [BUGFIX] Ingester: Avoid resharding for query when restart readonly ingesters. #6642
 
 ## 1.19.0 2025-02-27
 

pkg/ring/lifecycler.go

@@ -655,10 +655,15 @@ func (i *Lifecycler) stopping(runningError error) error {
 		i.setPreviousState(currentState)
 	}
 
-	// Mark ourselved as Leaving so no more samples are send to us.
-	err := i.changeState(context.Background(), LEAVING)
-	if err != nil {
-		level.Error(i.logger).Log("msg", "failed to set state to LEAVING", "ring", i.RingName, "err", err)
+	// We dont need to mark us as leaving if READONLY. There is not request sent to us.
+	// Also important to avoid this change so we dont have resharding(for querier) happen when READONLY restart as we extended shard on READONLY but not on LEAVING
+	// Query also keeps calling pods on LEAVING or JOINING not causing any difference if left on READONLY
+	if i.GetState() != READONLY {
+		// Mark ourselved as Leaving so no more samples are send to us.
+		err := i.changeState(context.Background(), LEAVING)
+		if err != nil {
+			level.Error(i.logger).Log("msg", "failed to set state to LEAVING", "ring", i.RingName, "err", err)
+		}
 	}
 
 	// Do the transferring / flushing on a background goroutine so we can continue

pkg/ring/lifecycler_test.go

@@ -743,6 +743,92 @@ func TestRestartIngester_DisabledHeartbeat_unregister_on_shutdown_false(t *testi
 	require.NoError(t, services.StopAndAwaitTerminated(context.Background(), l2))
 }
 
+func TestRestartIngester_READONLY(t *testing.T) {
+	ringStore, closer := consul.NewInMemoryClient(GetCodec(), log.NewNopLogger(), nil)
+	t.Cleanup(func() { assert.NoError(t, closer.Close()) })
+
+	var ringConfig Config
+	flagext.DefaultValues(&ringConfig)
+	ringConfig.KVStore.Mock = ringStore
+
+	r, err := New(ringConfig, "ingester", ringKey, log.NewNopLogger(), nil)
+	require.NoError(t, err)
+	require.NoError(t, services.StartAndAwaitRunning(context.Background(), r))
+
+	// poll function waits for a condition and returning actual state of the ingesters after the condition succeed.
+	poll := func(condition func(*Desc) bool) map[string]InstanceDesc {
+		var ingesters map[string]InstanceDesc
+		test.Poll(t, 5*time.Second, true, func() interface{} {
+			d, err := r.KVClient.Get(context.Background(), ringKey)
+			require.NoError(t, err)
+
+			desc, ok := d.(*Desc)
+
+			if ok {
+				ingesters = desc.Ingesters
+			}
+			return ok && condition(desc)
+		})
+
+		return ingesters
+	}
+
+	// Starts Ingester and wait it to became active
+	startIngesterAndWaitState := func(ingId string, addr string, expectedState InstanceState) *Lifecycler {
+		lifecyclerConfig := testLifecyclerConfigWithAddr(ringConfig, ingId, addr)
+		lifecyclerConfig.UnregisterOnShutdown = false
+		lifecycler, err := NewLifecycler(lifecyclerConfig, &noopFlushTransferer{}, "lifecycler", ringKey, true, true, log.NewNopLogger(), nil)
+		require.NoError(t, err)
+		require.NoError(t, services.StartAndAwaitRunning(context.Background(), lifecycler))
+		poll(func(desc *Desc) bool {
+			return desc.Ingesters[ingId].State == expectedState
+		})
+		return lifecycler
+	}
+
+	l1 := startIngesterAndWaitState("ing1", "0.0.0.0", ACTIVE)
+	l2 := startIngesterAndWaitState("ing2", "0.0.0.0", ACTIVE)
+
+	err = l2.ChangeState(context.Background(), READONLY)
+	require.NoError(t, err)
+	poll(func(desc *Desc) bool {
+		return desc.Ingesters["ing2"].State == READONLY
+	})
+
+	ingesters := poll(func(desc *Desc) bool {
+		return len(desc.Ingesters) == 2 && desc.Ingesters["ing1"].State == ACTIVE && desc.Ingesters["ing2"].State == READONLY
+	})
+
+	// Both Ingester should be active and running
+	assert.Equal(t, ACTIVE, ingesters["ing1"].State)
+	assert.Equal(t, READONLY, ingesters["ing2"].State)
+
+	// Stop ingester 1 gracefully should leave it on LEAVING STATE on the ring
+	require.NoError(t, services.StopAndAwaitTerminated(context.Background(), l1))
+	// Stop ingester 2 gracefully should keep on READONLY
+	require.NoError(t, services.StopAndAwaitTerminated(context.Background(), l2))
+
+	ingesters = poll(func(desc *Desc) bool {
+		return len(desc.Ingesters) == 2 && desc.Ingesters["ing1"].State == LEAVING
+	})
+
+	assert.Equal(t, LEAVING, ingesters["ing1"].State)
+	assert.Equal(t, READONLY, ingesters["ing2"].State)
+
+	// Start Ingester1 again - Should flip back to ACTIVE in the ring
+	defer services.StopAndAwaitTerminated(context.Background(), startIngesterAndWaitState("ing1", "0.0.0.0", ACTIVE)) //nolint:errcheck
+
+	// Start Ingester2 again - Should keep on READONLY
+	defer services.StopAndAwaitTerminated(context.Background(), startIngesterAndWaitState("ing2", "0.0.0.0", READONLY)) //nolint:errcheck
+
+	ingesters = poll(func(desc *Desc) bool {
+		return len(desc.Ingesters) == 2 && desc.Ingesters["ing1"].State == ACTIVE
+	})
+
+	assert.Equal(t, ACTIVE, ingesters["ing1"].State)
+	assert.Equal(t, READONLY, ingesters["ing2"].State)
+}
+
 func TestTokenFileOnDisk(t *testing.T) {
 	ringStore, closer := consul.NewInMemoryClient(GetCodec(), log.NewNopLogger(), nil)
 	t.Cleanup(func() { assert.NoError(t, closer.Close()) })