Propagate block changes to all of the cluster nodes in plugin mode (#1213)

Co-authored-by: Jesús Espino <jespinog@gmail.com>

mattermost-plugin/server/plugin.go

@@ -178,6 +178,10 @@ func (p *Plugin) OnDeactivate() error {
 	return p.server.Shutdown()
 }
 
+func (p *Plugin) OnPluginClusterEvent(_ *plugin.Context, ev mmModel.PluginClusterEvent) {
+	p.wsPluginAdapter.HandleClusterEvent(ev)
+}
+
 // ServeHTTP demonstrates a plugin that handles HTTP requests by greeting the world.
 func (p *Plugin) ServeHTTP(_ *plugin.Context, w http.ResponseWriter, r *http.Request) {
 	router := p.server.GetRootRouter()

server/ws/common.go

@@ -0,0 +1,20 @@
+package ws
+
+import (
+	"github.com/mattermost/focalboard/server/model"
+)
+
+// UpdateMsg is sent on block updates.
+type UpdateMsg struct {
+	Action string      `json:"action"`
+	Block  model.Block `json:"block"`
+}
+
+// WebsocketCommand is an incoming command from the client.
+type WebsocketCommand struct {
+	Action      string   `json:"action"`
+	WorkspaceID string   `json:"workspaceId"`
+	Token       string   `json:"token"`
+	ReadToken   string   `json:"readToken"`
+	BlockIDs    []string `json:"blockIds"`
+}

server/ws/plugin_adapter.go

@@ -285,6 +285,30 @@ func (pa *PluginAdapter) getUserIDsForWorkspace(workspaceID string) []string {
 	return userIDs
 }
 
+// sendWorkspaceMessageSkipCluster sends a message to all the users
+// with a websocket client connected to.
+func (pa *PluginAdapter) sendWorkspaceMessageSkipCluster(workspaceID string, payload map[string]interface{}) {
+	userIDs := pa.getUserIDsForWorkspace(workspaceID)
+	for _, userID := range userIDs {
+		pa.api.PublishWebSocketEvent(websocketActionUpdateBlock, payload, &mmModel.WebsocketBroadcast{UserId: userID})
+	}
+}
+
+// sendWorkspaceMessage sends and propagates a message that is aimed
+// for all the users that are subscribed to a given workspace.
+func (pa *PluginAdapter) sendWorkspaceMessage(workspaceID string, payload map[string]interface{}) {
+	go func() {
+		clusterMessage := &ClusterMessage{
+			WorkspaceID: workspaceID,
+			Payload:     payload,
+		}
+
+		pa.sendMessageToCluster("websocket_message", clusterMessage)
+	}()
+
+	pa.sendWorkspaceMessageSkipCluster(workspaceID, payload)
+}
+
 func (pa *PluginAdapter) BroadcastBlockChange(workspaceID string, block model.Block) {
 	pa.api.LogInfo("BroadcastingBlockChange",
 		"workspaceID", workspaceID,
@@ -296,10 +320,7 @@ func (pa *PluginAdapter) BroadcastBlockChange(workspaceID string, block model.Bl
 		Block:  block,
 	}
 
-	userIDs := pa.getUserIDsForWorkspace(workspaceID)
-	for _, userID := range userIDs {
-		pa.api.PublishWebSocketEvent(websocketActionUpdateBlock, structToMap(message), &mmModel.WebsocketBroadcast{UserId: userID})
-	}
+	pa.sendWorkspaceMessage(workspaceID, structToMap(message))
 }
 
 func (pa *PluginAdapter) BroadcastBlockDelete(workspaceID, blockID, parentID string) {

server/ws/plugin_adapter_cluster.go

@@ -0,0 +1,50 @@
+package ws
+
+import (
+	"encoding/json"
+
+	mmModel "github.com/mattermost/mattermost-server/v6/model"
+)
+
+type ClusterMessage struct {
+	WorkspaceID string
+	Payload     map[string]interface{}
+}
+
+func (pa *PluginAdapter) sendMessageToCluster(id string, clusterMessage *ClusterMessage) {
+	b, err := json.Marshal(clusterMessage)
+	if err != nil {
+		pa.api.LogError("couldn't get JSON bytes from cluster message",
+			"id", id,
+			"err", err,
+		)
+		return
+	}
+
+	event := mmModel.PluginClusterEvent{Id: id, Data: b}
+	opts := mmModel.PluginClusterEventSendOptions{
+		SendType: mmModel.PluginClusterEventSendTypeReliable,
+	}
+
+	if err := pa.api.PublishPluginClusterEvent(event, opts); err != nil {
+		pa.api.LogError("error publishing cluster event",
+			"id", id,
+			"err", err,
+		)
+	}
+}
+
+func (pa *PluginAdapter) HandleClusterEvent(ev mmModel.PluginClusterEvent) {
+	pa.api.LogDebug("received cluster event", "id", ev.Id)
+
+	var clusterMessage ClusterMessage
+	if err := json.Unmarshal(ev.Data, &clusterMessage); err != nil {
+		pa.api.LogError("cannot unmarshal cluster message data",
+			"id", ev.Id,
+			"err", err,
+		)
+		return
+	}
+
+	pa.sendWorkspaceMessageSkipCluster(clusterMessage.WorkspaceID, clusterMessage.Payload)
+}

server/ws/server.go

@@ -64,21 +64,6 @@ type Server struct {
 	logger               *mlog.Logger
 }
 
-// UpdateMsg is sent on block updates.
-type UpdateMsg struct {
-	Action string      `json:"action"`
-	Block  model.Block `json:"block"`
-}
-
-// WebsocketCommand is an incoming command from the client.
-type WebsocketCommand struct {
-	Action      string   `json:"action"`
-	WorkspaceID string   `json:"workspaceId"`
-	Token       string   `json:"token"`
-	ReadToken   string   `json:"readToken"`
-	BlockIDs    []string `json:"blockIds"`
-}
-
 type websocketSession struct {
 	client *wsClient
 	userID string