Handle context.Canceled in active series requests (#7102)

* Handle context.Canceled errors in callback for `forReplicationSet`

pkg/distributor/distributor.go

@@ -1832,11 +1832,20 @@ func (d *Distributor) ActiveSeries(ctx context.Context, matchers []*labels.Match
 	res := newActiveSeriesResponse(d.hashCollisionCount, maxResponseSize)
 
 	ingesterQuery := func(ctx context.Context, client ingester_client.IngesterClient) (any, error) {
+		// This function is invoked purely for its side effects on the captured
+		// activeSeriesResponse, its return value is never used.
+		type ignored struct{}
+
 		log, ctx := spanlogger.NewWithLogger(ctx, d.log, "Distributor.ActiveSeries.queryIngester")
 		defer log.Finish()
 
 		stream, err := client.ActiveSeries(ctx, req)
 		if err != nil {
+			if errors.Is(err, context.Canceled) {
+				return ignored{}, nil
+			}
+			level.Error(log).Log("msg", "error creating active series response stream", "err", err)
+			ext.Error.Set(log.Span, true)
 			return nil, err
 		}
 
@@ -1849,9 +1858,13 @@ func (d *Distributor) ActiveSeries(ctx context.Context, matchers []*labels.Match
 
 		for {
 			msg, err := stream.Recv()
-			if errors.Is(err, io.EOF) {
-				break
-			} else if err != nil {
+			if err != nil {
+				if errors.Is(err, io.EOF) {
+					break
+				}
+				if errors.Is(err, context.Canceled) {
+					return ignored{}, nil
+				}
 				level.Error(log).Log("msg", "error receiving active series response", "err", err)
 				ext.Error.Set(log.Span, true)
 				return nil, err
@@ -1863,7 +1876,7 @@ func (d *Distributor) ActiveSeries(ctx context.Context, matchers []*labels.Match
 			}
 		}
 
-		return nil, nil
+		return ignored{}, nil
 	}
 
 	_, err = forReplicationSet(ctx, d, replicationSet, ingesterQuery)