Added local file buffer for replication service. (#1004)

This allows the service to store events to a local file while the
master node is down.

api/mock/gen.go

@@ -1,3 +1,3 @@
-//go:generate mockgen  -destination api_mock.go www.velocidex.com/golang/velociraptor/api/proto APIClient
+//go:generate mockgen  -destination api_mock.go www.velocidex.com/golang/velociraptor/api/proto APIClient,API_WatchEventClient
 
 package mock_proto

api/replication.go

@@ -37,6 +37,8 @@ func streamEvents(
 		return err
 	}
 
+	// The API service is running on the master only! This means
+	// the journal service is local.
 	output_chan, cancel := journal.Watch(ctx, in.Queue)
 	defer cancel()
 

services/hunt_manager/hunt_manager.go

@@ -272,10 +272,15 @@ func (self *HuntManager) ProcessParticipation(
 			participation_row.ClientId, err)
 	}
 
+	// If the hunt ran on the client already we just ignore
+	// it. This is possible because the client may not have
+	// updated its last hunt number in time to have a number of
+	// hunt participation messages sent for it from different
+	// frontends.
 	err = checkHuntRanOnClient(config_obj, participation_row.ClientId,
 		participation_row.HuntId)
 	if err != nil {
-		return err
+		return nil
 	}
 
 	// Get hunt information about this hunt.