Plugin API hook for Shared Channel file attachment sync (#25874)

* option for auto inviting plugin to all shared channels.

* auto-invite remotes to shared channels when flag set

* fix unit test

* immediately ping new remotes; fix unique siteurl bug

* make i18n-extract

* fix translations

* plugin hooks for file attachments

* hook for profile image sync

* fix profile image sync

* fix unit test

---------

Co-authored-by: Mattermost Build <build@mattermost.com>

server/channels/app/app_iface.go

@@ -271,9 +271,15 @@ type AppIface interface {
 	MoveChannel(c request.CTX, team *model.Team, channel *model.Channel, user *model.User) *model.AppError
 	// NotifySessionsExpired is called periodically from the job server to notify any mobile sessions that have expired.
 	NotifySessionsExpired() error
-	// OnSharedChannelsPing is called by the Shared Channels service for a registered plugin wto check that the plugin
+	// OnSharedChannelsAttachmentSyncMsg is called by the Shared Channels service for a registered plugin when a file attachment
+	// needs to be synchronized.
+	OnSharedChannelsAttachmentSyncMsg(fi *model.FileInfo, post *model.Post, rc *model.RemoteCluster) error
+	// OnSharedChannelsPing is called by the Shared Channels service for a registered plugin to check that the plugin
 	// is still responding and has a connection to any upstream services it needs (e.g. MS Graph API).
 	OnSharedChannelsPing(rc *model.RemoteCluster) bool
+	// OnSharedChannelsProfileImageSyncMsg is called by the Shared Channels service for a registered plugin when a user's
+	// profile image needs to be synchronized.
+	OnSharedChannelsProfileImageSyncMsg(user *model.User, rc *model.RemoteCluster) error
 	// OnSharedChannelsSyncMsg is called by the Shared Channels service for a registered plugin when there is new content
 	// that needs to be synchronized.
 	OnSharedChannelsSyncMsg(msg *model.SyncMsg, rc *model.RemoteCluster) (model.SyncResponse, error)

server/channels/app/opentracing/opentracing_layer.go

@@ -12858,6 +12858,28 @@ func (a *OpenTracingAppLayer) NotifySharedChannelUserUpdate(user *model.User) {
 	a.app.NotifySharedChannelUserUpdate(user)
 }
 
+func (a *OpenTracingAppLayer) OnSharedChannelsAttachmentSyncMsg(fi *model.FileInfo, post *model.Post, rc *model.RemoteCluster) error {
+	origCtx := a.ctx
+	span, newCtx := tracing.StartSpanWithParentByContext(a.ctx, "app.OnSharedChannelsAttachmentSyncMsg")
+
+	a.ctx = newCtx
+	a.app.Srv().Store().SetContext(newCtx)
+	defer func() {
+		a.app.Srv().Store().SetContext(origCtx)
+		a.ctx = origCtx
+	}()
+
+	defer span.Finish()
+	resultVar0 := a.app.OnSharedChannelsAttachmentSyncMsg(fi, post, rc)
+
+	if resultVar0 != nil {
+		span.LogFields(spanlog.Error(resultVar0))
+		ext.Error.Set(span, true)
+	}
+
+	return resultVar0
+}
+
 func (a *OpenTracingAppLayer) OnSharedChannelsPing(rc *model.RemoteCluster) bool {
 	origCtx := a.ctx
 	span, newCtx := tracing.StartSpanWithParentByContext(a.ctx, "app.OnSharedChannelsPing")
@@ -12875,6 +12897,28 @@ func (a *OpenTracingAppLayer) OnSharedChannelsPing(rc *model.RemoteCluster) bool
 	return resultVar0
 }
 
+func (a *OpenTracingAppLayer) OnSharedChannelsProfileImageSyncMsg(user *model.User, rc *model.RemoteCluster) error {
+	origCtx := a.ctx
+	span, newCtx := tracing.StartSpanWithParentByContext(a.ctx, "app.OnSharedChannelsProfileImageSyncMsg")
+
+	a.ctx = newCtx
+	a.app.Srv().Store().SetContext(newCtx)
+	defer func() {
+		a.app.Srv().Store().SetContext(origCtx)
+		a.ctx = origCtx
+	}()
+
+	defer span.Finish()
+	resultVar0 := a.app.OnSharedChannelsProfileImageSyncMsg(user, rc)
+
+	if resultVar0 != nil {
+		span.LogFields(spanlog.Error(resultVar0))
+		ext.Error.Set(span, true)
+	}
+
+	return resultVar0
+}
+
 func (a *OpenTracingAppLayer) OnSharedChannelsSyncMsg(msg *model.SyncMsg, rc *model.RemoteCluster) (model.SyncResponse, error) {
 	origCtx := a.ctx
 	span, newCtx := tracing.StartSpanWithParentByContext(a.ctx, "app.OnSharedChannelsSyncMsg")

server/channels/app/remote_cluster.go

@@ -13,6 +13,7 @@ import (
 	"github.com/mattermost/mattermost/server/v8/platform/services/remotecluster"
 
 	"github.com/mattermost/mattermost/server/public/model"
+	"github.com/mattermost/mattermost/server/public/shared/mlog"
 )
 
 func (a *App) RegisterPluginForSharedChannels(opts model.RegisterPluginOpts) (remoteID string, err error) {
@@ -27,6 +28,11 @@ func (a *App) RegisterPluginForSharedChannels(opts model.RegisterPluginOpts) (re
 
 	// if plugin is already registered then treat this as an update.
 	if rc != nil {
+		a.Log().Debug("Plugin already registered for Shared Channels",
+			mlog.String("plugin_id", opts.PluginID),
+			mlog.String("remote_id", rc.RemoteId),
+		)
+
 		rc.DisplayName = opts.Displayname
 		rc.Options = opts.GetOptionFlags()
 
@@ -51,6 +57,11 @@ func (a *App) RegisterPluginForSharedChannels(opts model.RegisterPluginOpts) (re
 		return "", err
 	}
 
+	a.Log().Debug("Registered new plugin for Shared Channels",
+		mlog.String("plugin_id", opts.PluginID),
+		mlog.String("remote_id", rcSaved.RemoteId),
+	)
+
 	return rcSaved.RemoteId, nil
 }
 

server/channels/app/shared_channel.go

@@ -9,6 +9,7 @@ import (
 	"net/http"
 
 	"github.com/mattermost/mattermost/server/public/model"
+	"github.com/mattermost/mattermost/server/public/plugin"
 	"github.com/mattermost/mattermost/server/public/shared/mlog"
 	"github.com/mattermost/mattermost/server/public/shared/request"
 	"github.com/mattermost/mattermost/server/v8/channels/store"
@@ -301,17 +302,19 @@ func (a *App) SyncSharedChannel(channelID string) error {
 
 // Hooks
 
-var ErrPluginUnavailable = errors.New("plugin unavialable")
+var ErrPluginUnavailable = errors.New("plugin unavailable")
+
+func getPluginHooks(env *plugin.Environment, pluginID string) (plugin.Hooks, error) {
+	if env == nil {
+		return nil, ErrPluginUnavailable
+	}
+	return env.HooksForPlugin(pluginID)
+}
 
 // OnSharedChannelsSyncMsg is called by the Shared Channels service for a registered plugin when there is new content
 // that needs to be synchronized.
 func (a *App) OnSharedChannelsSyncMsg(msg *model.SyncMsg, rc *model.RemoteCluster) (model.SyncResponse, error) {
-	pluginsEnvironment := a.GetPluginsEnvironment()
-	if pluginsEnvironment == nil {
-		return model.SyncResponse{}, fmt.Errorf("cannot deliver sync msg to plugin %s: %w", rc.PluginID, ErrPluginUnavailable)
-	}
-
-	pluginHooks, err := pluginsEnvironment.HooksForPlugin(rc.PluginID)
+	pluginHooks, err := getPluginHooks(a.GetPluginsEnvironment(), rc.PluginID)
 	if err != nil {
 		return model.SyncResponse{}, fmt.Errorf("cannot deliver sync msg to plugin %s: %w", rc.PluginID, err)
 	}
@@ -319,16 +322,10 @@ func (a *App) OnSharedChannelsSyncMsg(msg *model.SyncMsg, rc *model.RemoteCluste
 	return pluginHooks.OnSharedChannelsSyncMsg(msg, rc)
 }
 
-// OnSharedChannelsPing is called by the Shared Channels service for a registered plugin wto check that the plugin
+// OnSharedChannelsPing is called by the Shared Channels service for a registered plugin to check that the plugin
 // is still responding and has a connection to any upstream services it needs (e.g. MS Graph API).
 func (a *App) OnSharedChannelsPing(rc *model.RemoteCluster) bool {
-	pluginsEnvironment := a.GetPluginsEnvironment()
-	if pluginsEnvironment == nil {
-		a.Log().Error("Ping for shared channels cannot get plugins env")
-		return false
-	}
-
-	pluginHooks, err := pluginsEnvironment.HooksForPlugin(rc.PluginID)
+	pluginHooks, err := getPluginHooks(a.GetPluginsEnvironment(), rc.PluginID)
 	if err != nil {
 		a.Log().Error("Ping for shared channels cannot get plugin hooks", mlog.String("plugin_id", rc.PluginID), mlog.Err(err))
 		return false
@@ -336,3 +333,25 @@ func (a *App) OnSharedChannelsPing(rc *model.RemoteCluster) bool {
 
 	return pluginHooks.OnSharedChannelsPing(rc)
 }
+
+// OnSharedChannelsAttachmentSyncMsg is called by the Shared Channels service for a registered plugin when a file attachment
+// needs to be synchronized.
+func (a *App) OnSharedChannelsAttachmentSyncMsg(fi *model.FileInfo, post *model.Post, rc *model.RemoteCluster) error {
+	pluginHooks, err := getPluginHooks(a.GetPluginsEnvironment(), rc.PluginID)
+	if err != nil {
+		return fmt.Errorf("cannot deliver file attachment sync msg to plugin %s: %w", rc.PluginID, err)
+	}
+
+	return pluginHooks.OnSharedChannelsAttachmentSyncMsg(fi, post, rc)
+}
+
+// OnSharedChannelsProfileImageSyncMsg is called by the Shared Channels service for a registered plugin when a user's
+// profile image needs to be synchronized.
+func (a *App) OnSharedChannelsProfileImageSyncMsg(user *model.User, rc *model.RemoteCluster) error {
+	pluginHooks, err := getPluginHooks(a.GetPluginsEnvironment(), rc.PluginID)
+	if err != nil {
+		return fmt.Errorf("cannot deliver user profile image sync msg to plugin %s: %w", rc.PluginID, err)
+	}
+
+	return pluginHooks.OnSharedChannelsProfileImageSyncMsg(user, rc)
+}

server/channels/store/sqlstore/remote_cluster_store.go

@@ -157,7 +157,7 @@ func (s sqlRemoteClusterStore) GetByPluginID(pluginID string) (*model.RemoteClus
 
 	var rc model.RemoteCluster
 	if err := s.GetReplicaX().Get(&rc, queryString, args...); err != nil {
-		return nil, errors.Wrapf(err, "failed to find RemoteCluster by plugin_id")
+		return nil, errors.Wrap(err, "failed to find RemoteCluster by plugin_id")
 	}
 	return &rc, nil
 }

server/channels/store/sqlstore/shared_channel_store.go

@@ -4,6 +4,7 @@
 package sqlstore
 
 import (
+	"context"
 	"database/sql"
 	"fmt"
 	"strings"
@@ -674,10 +675,10 @@ func (s SqlSharedChannelStore) GetSingleUser(userID string, channelID string, re
 
 	squery, args, err := s.getQueryBuilder().
 		Select(sharedChannelUserFields("")...).
-		From("SharedChannelUsers").
-		Where(sq.Eq{"SharedChannelUsers.UserId": userID}).
-		Where(sq.Eq{"SharedChannelUsers.RemoteId": remoteID}).
-		Where(sq.Eq{"SharedChannelUsers.ChannelId": channelID}).
+		From("SharedChannelUsers AS scu").
+		Where(sq.Eq{"scu.UserId": userID}).
+		Where(sq.Eq{"scu.ChannelId": channelID}).
+		Where(sq.Eq{"scu.RemoteId": remoteID}).
 		ToSql()
 
 	if err != nil {
@@ -760,46 +761,33 @@ func (s SqlSharedChannelStore) GetUsersForSync(filter model.GetUsersForSyncFilte
 
 // UpdateUserLastSyncAt updates the LastSyncAt timestamp for the specified SharedChannelUser.
 func (s SqlSharedChannelStore) UpdateUserLastSyncAt(userID string, channelID string, remoteID string) error {
-	var query string
-	if s.DriverName() == model.DatabaseDriverPostgres {
-		query = `
-		UPDATE
-			SharedChannelUsers AS scu
-		SET
-			LastSyncAt = GREATEST(Users.UpdateAt, Users.LastPictureUpdate)
-		FROM
-			Users
-		WHERE
-			Users.Id = scu.UserId AND scu.UserId = ? AND scu.ChannelId = ? AND scu.RemoteId = ?
-		`
-	} else if s.DriverName() == model.DatabaseDriverMysql {
-		query = `
-		UPDATE
-			SharedChannelUsers AS scu
-		INNER JOIN
-			Users ON scu.UserId = Users.Id
-		SET
-			LastSyncAt = GREATEST(Users.UpdateAt, Users.LastPictureUpdate)
-		WHERE
-			scu.UserId = ? AND scu.ChannelId = ? AND scu.RemoteId = ?
-		`
-	} else {
-		return errors.New("unsupported DB driver " + s.DriverName())
+	// fetching the user first creates a minor race condition. This is mitigated by ensuring that the
+	// LastUpdateAt is only ever increased. Doing it this way avoids the update with join that has differing
+	// syntax between MySQL and Postgres which Squirrel cannot handle.  It also allows us to return
+	// a proper error when trying to update for a non-existent user, which cannot be done by checking RowsAffected
+	// when doing updates; RowsAffected=0 when the LastUpdateAt doesn't change and is the same result if user doesn't
+	// exist.
+	user, err := s.stores.user.Get(context.Background(), userID)
+	if err != nil {
+		return err
 	}
 
-	result, err := s.GetMasterX().Exec(query, userID, channelID, remoteID)
+	updateAt := maxInt64(user.UpdateAt, user.LastPictureUpdate)
+
+	query := s.getQueryBuilder().
+		Update("SharedChannelUsers AS scu").
+		Set("LastSyncAt", sq.Expr("GREATEST(scu.LastSyncAt, ?)", updateAt)).
+		Where(sq.Eq{
+			"scu.UserId":    userID,
+			"scu.ChannelId": channelID,
+			"scu.RemoteId":  remoteID,
+		})
+
+	_, err = s.GetMasterX().ExecBuilder(query)
 	if err != nil {
 		return fmt.Errorf("failed to update LastSyncAt for SharedChannelUser with userId=%s, channelId=%s, remoteId=%s: %w",
 			userID, channelID, remoteID, err)
 	}
-
-	count, err := result.RowsAffected()
-	if err != nil {
-		return errors.Wrap(err, "failed to determine rows affected")
-	}
-	if count == 0 {
-		return fmt.Errorf("SharedChannelUser not found: userId=%s, channelId=%s, remoteId=%s", userID, channelID, remoteID)
-	}
 	return nil
 }
 

server/channels/store/sqlstore/utils.go

@@ -244,3 +244,10 @@ func trimInput(input string) string {
 	}
 	return input
 }
+
+func maxInt64(a, b int64) int64 {
+	if a > b {
+		return a
+	}
+	return b
+}

server/channels/store/storetest/remote_cluster_store.go

@@ -21,6 +21,7 @@ func TestRemoteClusterStore(t *testing.T, rctx request.CTX, ss store.Store) {
 	t.Run("RemoteClusterSave", func(t *testing.T) { testRemoteClusterSave(t, rctx, ss) })
 	t.Run("RemoteClusterDelete", func(t *testing.T) { testRemoteClusterDelete(t, rctx, ss) })
 	t.Run("RemoteClusterGet", func(t *testing.T) { testRemoteClusterGet(t, rctx, ss) })
+	t.Run("RemoteClusterGetByPluginID", func(t *testing.T) { testRemoteClusterGetByPluginID(t, rctx, ss) })
 	t.Run("RemoteClusterGetAll", func(t *testing.T) { testRemoteClusterGetAll(t, rctx, ss) })
 	t.Run("RemoteClusterGetByTopic", func(t *testing.T) { testRemoteClusterGetByTopic(t, rctx, ss) })
 	t.Run("RemoteClusterUpdateTopics", func(t *testing.T) { testRemoteClusterUpdateTopics(t, rctx, ss) })
@@ -191,6 +192,31 @@ func testRemoteClusterGet(t *testing.T, rctx request.CTX, ss store.Store) {
 	})
 }
 
+func testRemoteClusterGetByPluginID(t *testing.T, rctx request.CTX, ss store.Store) {
+	const pluginID = "com.acme.bogus.plugin"
+
+	t.Run("GetByPluginID", func(t *testing.T) {
+		rc := &model.RemoteCluster{
+			Name:      "shortlived_remote_3",
+			SiteURL:   makeSiteURL(),
+			CreatorId: model.NewId(),
+			PluginID:  pluginID,
+		}
+		rcSaved, err := ss.RemoteCluster().Save(rc)
+		require.NoError(t, err)
+
+		rcGet, err := ss.RemoteCluster().GetByPluginID(pluginID)
+		require.NoError(t, err)
+		require.Equal(t, rcSaved.RemoteId, rcGet.RemoteId)
+		require.Equal(t, pluginID, rcGet.PluginID)
+	})
+
+	t.Run("GetByPluginID not found", func(t *testing.T) {
+		_, err := ss.RemoteCluster().GetByPluginID(model.NewId())
+		require.Error(t, err)
+	})
+}
+
 func testRemoteClusterGetAll(t *testing.T, rctx request.CTX, ss store.Store) {
 	require.NoError(t, clearRemoteClusters(ss))
 

server/platform/services/remotecluster/ping.go

@@ -66,7 +66,8 @@ func (rcs *Service) pingGenerator(pingChan chan *model.RemoteCluster, done <-cha
 		}
 
 		for _, rc := range remotes {
-			if rc.SiteURL != "" || rc.PluginID != "" { // filter out unconfirmed invites
+			// filter out unconfirmed invites so we don't ping them without permission
+			if rc.IsConfirmed() {
 				pingChan <- rc
 			}
 		}

server/platform/services/sharedchannel/attachment.go

@@ -41,6 +41,10 @@ func (scs *Service) sendAttachmentForRemote(fi *model.FileInfo, post *model.Post
 		return fmt.Errorf("cannot update remote cluster for remote id %s; Remote Cluster Service not enabled", rc.RemoteId)
 	}
 
+	if rc.IsPlugin() {
+		return scs.sendAttachmentToPlugin(fi, post, rc)
+	}
+
 	us := &model.UploadSession{
 		Id:        model.NewId(),
 		Type:      model.UploadTypeAttachment,
@@ -120,11 +124,7 @@ func (scs *Service) sendAttachmentForRemote(fi *model.FileInfo, post *model.Post
 		}
 
 		// save file attachment record in SharedChannelAttachments table
-		sca := &model.SharedChannelAttachment{
-			FileId:   fi.Id,
-			RemoteId: rc.RemoteId,
-		}
-		if _, err2 := scs.server.GetStore().SharedChannel().UpsertAttachment(sca); err2 != nil {
+		if err2 := scs.saveSharedAttachment(&fi, rc); err2 != nil {
 			scs.server.Log().Log(mlog.LvlSharedChannelServiceError, "error saving SharedChannelAttachment",
 				mlog.String("remote", rc.DisplayName),
 				mlog.String("uploadId", usResp.Id),
@@ -140,6 +140,24 @@ func (scs *Service) sendAttachmentForRemote(fi *model.FileInfo, post *model.Post
 	})
 }
 
+// sendAttachmentToPlugin asynchronously sends a file attachment to a remote cluster.
+func (scs *Service) sendAttachmentToPlugin(fi *model.FileInfo, post *model.Post, rc *model.RemoteCluster) error {
+	if err := scs.app.OnSharedChannelsAttachmentSyncMsg(fi, post, rc); err != nil {
+		return fmt.Errorf("cannot send attachment to plugin %s: %w", rc.PluginID, err)
+	}
+	return scs.saveSharedAttachment(fi, rc)
+}
+
+// saveSharedAttachment saves the attachment in SharedChannelAttachments table.
+func (scs *Service) saveSharedAttachment(fi *model.FileInfo, rc *model.RemoteCluster) error {
+	sca := &model.SharedChannelAttachment{
+		FileId:   fi.Id,
+		RemoteId: rc.RemoteId,
+	}
+	_, err := scs.server.GetStore().SharedChannel().UpsertAttachment(sca)
+	return err
+}
+
 // onReceiveUploadCreate is called when a message requesting to create an upload session is received.  An upload session is
 // created and the id returned in the response.
 func (scs *Service) onReceiveUploadCreate(msg model.RemoteClusterMsg, rc *model.RemoteCluster, response *remotecluster.Response) error {

server/platform/services/sharedchannel/mock_AppIface_test.go

@@ -314,6 +314,34 @@ func (_m *MockAppIface) NotifySharedChannelUserUpdate(user *model.User) {
 	_m.Called(user)
 }
 
+// OnSharedChannelsAttachmentSyncMsg provides a mock function with given fields: fi, post, rc
+func (_m *MockAppIface) OnSharedChannelsAttachmentSyncMsg(fi *model.FileInfo, post *model.Post, rc *model.RemoteCluster) error {
+	ret := _m.Called(fi, post, rc)
+
+	var r0 error
+	if rf, ok := ret.Get(0).(func(*model.FileInfo, *model.Post, *model.RemoteCluster) error); ok {
+		r0 = rf(fi, post, rc)
+	} else {
+		r0 = ret.Error(0)
+	}
+
+	return r0
+}
+
+// OnSharedChannelsProfileImageSyncMsg provides a mock function with given fields: user, rc
+func (_m *MockAppIface) OnSharedChannelsProfileImageSyncMsg(user *model.User, rc *model.RemoteCluster) error {
+	ret := _m.Called(user, rc)
+
+	var r0 error
+	if rf, ok := ret.Get(0).(func(*model.User, *model.RemoteCluster) error); ok {
+		r0 = rf(user, rc)
+	} else {
+		r0 = ret.Error(0)
+	}
+
+	return r0
+}
+
 // OnSharedChannelsSyncMsg provides a mock function with given fields: msg, rc
 func (_m *MockAppIface) OnSharedChannelsSyncMsg(msg *model.SyncMsg, rc *model.RemoteCluster) (model.SyncResponse, error) {
 	ret := _m.Called(msg, rc)

server/platform/services/sharedchannel/service.go

@@ -64,6 +64,8 @@ type AppIface interface {
 	InvalidateCacheForUser(userID string)
 	NotifySharedChannelUserUpdate(user *model.User)
 	OnSharedChannelsSyncMsg(msg *model.SyncMsg, rc *model.RemoteCluster) (model.SyncResponse, error)
+	OnSharedChannelsAttachmentSyncMsg(fi *model.FileInfo, post *model.Post, rc *model.RemoteCluster) error
+	OnSharedChannelsProfileImageSyncMsg(user *model.User, rc *model.RemoteCluster) error
 }
 
 // errNotFound allows checking against Store.ErrNotFound errors without making Store a dependency.

server/platform/services/sharedchannel/sync_send.go

@@ -402,11 +402,17 @@ func (scs *Service) shouldUserSync(user *model.User, channelID string, rc *model
 		}
 		if _, err = scs.server.GetStore().SharedChannel().SaveUser(scu); err != nil {
 			scs.server.Log().Log(mlog.LvlSharedChannelServiceError, "Error adding user to shared channel users",
-				mlog.String("remote_id", rc.RemoteId),
 				mlog.String("user_id", user.Id),
 				mlog.String("channel_id", user.Id),
+				mlog.String("remote_id", rc.RemoteId),
 				mlog.Err(err),
 			)
+		} else {
+			scs.server.Log().Log(mlog.LvlSharedChannelServiceDebug, "Added user to shared channel users",
+				mlog.String("user_id", user.Id),
+				mlog.String("channel_id", user.Id),
+				mlog.String("remote_id", rc.RemoteId),
+			)
 		}
 		return true, true, nil
 	}
@@ -420,30 +426,55 @@ func (scs *Service) syncProfileImage(user *model.User, channelID string, rc *mod
 		return
 	}
 
+	if rc.IsPlugin() {
+		scs.sendProfileImageToPlugin(user, channelID, rc)
+		return
+	}
+
 	ctx, cancel := context.WithTimeout(context.Background(), ProfileImageSyncTimeout)
 	defer cancel()
 
 	rcs.SendProfileImage(ctx, user.Id, rc, scs.app, func(userId string, rc *model.RemoteCluster, resp *remotecluster.Response, err error) {
 		if resp.IsSuccess() {
-			scs.server.Log().Log(mlog.LvlSharedChannelServiceDebug, "Users profile image synchronized",
-				mlog.String("remote_id", rc.RemoteId),
-				mlog.String("user_id", user.Id),
-			)
-
-			if err2 := scs.server.GetStore().SharedChannel().UpdateUserLastSyncAt(user.Id, channelID, rc.RemoteId); err2 != nil {
-				scs.server.Log().Log(mlog.LvlSharedChannelServiceError, "Error updating users LastSyncTime after profile image update",
-					mlog.String("remote_id", rc.RemoteId),
-					mlog.String("user_id", user.Id),
-					mlog.Err(err2),
-				)
-			}
+			scs.recordProfileImageSuccess(user.Id, channelID, rc.RemoteId)
 			return
 		}
 
 		scs.server.Log().Log(mlog.LvlSharedChannelServiceError, "Error synchronizing users profile image",
-			mlog.String("remote_id", rc.RemoteId),
 			mlog.String("user_id", user.Id),
+			mlog.String("channel_id", channelID),
+			mlog.String("remote_id", rc.RemoteId),
 			mlog.Err(err),
 		)
 	})
 }
+
+func (scs *Service) sendProfileImageToPlugin(user *model.User, channelID string, rc *model.RemoteCluster) {
+	if err := scs.app.OnSharedChannelsProfileImageSyncMsg(user, rc); err != nil {
+		scs.server.Log().Log(mlog.LvlSharedChannelServiceError, "Error synchronizing users profile image for plugin",
+			mlog.String("user_id", user.Id),
+			mlog.String("channel_id", channelID),
+			mlog.String("remote_id", rc.RemoteId),
+			mlog.Err(err),
+		)
+	}
+	scs.recordProfileImageSuccess(user.Id, channelID, rc.RemoteId)
+}
+
+func (scs *Service) recordProfileImageSuccess(userID, channelID, remoteID string) {
+	scs.server.Log().Log(mlog.LvlSharedChannelServiceDebug, "Users profile image synchronized",
+		mlog.String("user_id", userID),
+		mlog.String("channel_id", channelID),
+		mlog.String("remote_id", remoteID),
+	)
+
+	// update LastSyncAt for user in SharedChannelUsers table
+	if err := scs.server.GetStore().SharedChannel().UpdateUserLastSyncAt(userID, channelID, remoteID); err != nil {
+		scs.server.Log().Log(mlog.LvlSharedChannelServiceError, "Error updating users LastSyncTime after profile image update",
+			mlog.String("user_id", userID),
+			mlog.String("channel_id", channelID),
+			mlog.String("remote_id", remoteID),
+			mlog.Err(err),
+		)
+	}
+}

server/platform/services/sharedchannel/sync_send_remote.go

@@ -235,13 +235,17 @@ func (scs *Service) fetchPostsForSync(sd *syncData) error {
 	count := len(posts)
 	sd.posts = appendPosts(sd.posts, posts, scs.server.GetStore().Post(), cursor.LastPostCreateAt)
 
+	cache := postsSliceToMap(posts)
+
 	// Fill remaining batch capacity with updated posts.
 	if len(posts) < MaxPostsPerSync {
 		options.SinceCreateAt = false
+		// use 'nextcursor' as it has the correct xxxUpdateAt values, and the updsted xxxCreateAt values.
 		posts, nextCursor, err = scs.server.GetStore().Post().GetPostsSinceForSync(options, nextCursor, MaxPostsPerSync-len(posts))
 		if err != nil {
 			return fmt.Errorf("could not fetch modified posts for sync: %w", err)
 		}
+		posts = reducePostsSliceInCache(posts, cache)
 		count += len(posts)
 		sd.posts = appendPosts(sd.posts, posts, scs.server.GetStore().Post(), cursor.LastPostUpdateAt)
 	}

server/platform/services/sharedchannel/util.go

@@ -130,3 +130,21 @@ func isNotFoundError(err error) bool {
 	var errNotFound *store.ErrNotFound
 	return errors.As(err, &errNotFound)
 }
+
+func postsSliceToMap(posts []*model.Post) map[string]*model.Post {
+	m := make(map[string]*model.Post, len(posts))
+	for _, p := range posts {
+		m[p.Id] = p
+	}
+	return m
+}
+
+func reducePostsSliceInCache(posts []*model.Post, cache map[string]*model.Post) []*model.Post {
+	reduced := make([]*model.Post, 0, len(posts))
+	for _, p := range posts {
+		if _, ok := cache[p.Id]; !ok {
+			reduced = append(reduced, p)
+		}
+	}
+	return reduced
+}

server/public/model/remote_cluster.go

@@ -174,8 +174,11 @@ func (rc *RemoteCluster) IsPlugin() bool {
 
 func (rc *RemoteCluster) GetSiteURL() string {
 	siteURL := rc.SiteURL
+	if strings.HasPrefix(siteURL, SiteURLPending) {
+		siteURL = "..."
+	}
 	if strings.HasPrefix(siteURL, SiteURLPending) || strings.HasPrefix(siteURL, SiteURLPlugin) {
-		siteURL = ""
+		siteURL = "plugin"
 	}
 	return siteURL
 }

server/public/plugin/client_rpc_generated.go

@@ -1052,6 +1052,79 @@ func (s *hooksRPCServer) PreferencesHaveChanged(args *Z_PreferencesHaveChangedAr
 	return nil
 }
 
+func init() {
+	hookNameToId["OnSharedChannelsAttachmentSyncMsg"] = OnSharedChannelsAttachmentSyncMsgID
+}
+
+type Z_OnSharedChannelsAttachmentSyncMsgArgs struct {
+	A *model.FileInfo
+	B *model.Post
+	C *model.RemoteCluster
+}
+
+type Z_OnSharedChannelsAttachmentSyncMsgReturns struct {
+	A error
+}
+
+func (g *hooksRPCClient) OnSharedChannelsAttachmentSyncMsg(fi *model.FileInfo, post *model.Post, rc *model.RemoteCluster) error {
+	_args := &Z_OnSharedChannelsAttachmentSyncMsgArgs{fi, post, rc}
+	_returns := &Z_OnSharedChannelsAttachmentSyncMsgReturns{}
+	if g.implemented[OnSharedChannelsAttachmentSyncMsgID] {
+		if err := g.client.Call("Plugin.OnSharedChannelsAttachmentSyncMsg", _args, _returns); err != nil {
+			g.log.Error("RPC call OnSharedChannelsAttachmentSyncMsg to plugin failed.", mlog.Err(err))
+		}
+	}
+	return _returns.A
+}
+
+func (s *hooksRPCServer) OnSharedChannelsAttachmentSyncMsg(args *Z_OnSharedChannelsAttachmentSyncMsgArgs, returns *Z_OnSharedChannelsAttachmentSyncMsgReturns) error {
+	if hook, ok := s.impl.(interface {
+		OnSharedChannelsAttachmentSyncMsg(fi *model.FileInfo, post *model.Post, rc *model.RemoteCluster) error
+	}); ok {
+		returns.A = hook.OnSharedChannelsAttachmentSyncMsg(args.A, args.B, args.C)
+		returns.A = encodableError(returns.A)
+	} else {
+		return encodableError(fmt.Errorf("Hook OnSharedChannelsAttachmentSyncMsg called but not implemented."))
+	}
+	return nil
+}
+
+func init() {
+	hookNameToId["OnSharedChannelsProfileImageSyncMsg"] = OnSharedChannelsProfileImageSyncMsgID
+}
+
+type Z_OnSharedChannelsProfileImageSyncMsgArgs struct {
+	A *model.User
+	B *model.RemoteCluster
+}
+
+type Z_OnSharedChannelsProfileImageSyncMsgReturns struct {
+	A error
+}
+
+func (g *hooksRPCClient) OnSharedChannelsProfileImageSyncMsg(user *model.User, rc *model.RemoteCluster) error {
+	_args := &Z_OnSharedChannelsProfileImageSyncMsgArgs{user, rc}
+	_returns := &Z_OnSharedChannelsProfileImageSyncMsgReturns{}
+	if g.implemented[OnSharedChannelsProfileImageSyncMsgID] {
+		if err := g.client.Call("Plugin.OnSharedChannelsProfileImageSyncMsg", _args, _returns); err != nil {
+			g.log.Error("RPC call OnSharedChannelsProfileImageSyncMsg to plugin failed.", mlog.Err(err))
+		}
+	}
+	return _returns.A
+}
+
+func (s *hooksRPCServer) OnSharedChannelsProfileImageSyncMsg(args *Z_OnSharedChannelsProfileImageSyncMsgArgs, returns *Z_OnSharedChannelsProfileImageSyncMsgReturns) error {
+	if hook, ok := s.impl.(interface {
+		OnSharedChannelsProfileImageSyncMsg(user *model.User, rc *model.RemoteCluster) error
+	}); ok {
+		returns.A = hook.OnSharedChannelsProfileImageSyncMsg(args.A, args.B)
+		returns.A = encodableError(returns.A)
+	} else {
+		return encodableError(fmt.Errorf("Hook OnSharedChannelsProfileImageSyncMsg called but not implemented."))
+	}
+	return nil
+}
+
 type Z_RegisterCommandArgs struct {
 	A *model.Command
 }

server/public/plugin/hooks.go

@@ -58,6 +58,8 @@ const (
 	OnSharedChannelsSyncMsgID                 = 40
 	OnSharedChannelsPingID                    = 41
 	PreferencesHaveChangedID                  = 42
+	OnSharedChannelsAttachmentSyncMsgID       = 43
+	OnSharedChannelsProfileImageSyncMsgID     = 44
 	TotalHooksID                              = iota
 )
 
@@ -362,4 +364,22 @@ type Hooks interface {
 	//
 	// Minimum server version: 9.5
 	PreferencesHaveChanged(c *Context, preferences []model.Preference)
+
+	// OnSharedChannelsAttachmentSyncMsg is invoked for plugins that wish to receive synchronization messages from the
+	// Shared Channels service for which they have been invited via InviteRemote.  Each call represents one file attachment
+	// to be synchronized.
+	//
+	// The cursor will be advanced based on the timestamp returned if no error is returned.
+	//
+	// Minimum server version: 9.5
+	OnSharedChannelsAttachmentSyncMsg(fi *model.FileInfo, post *model.Post, rc *model.RemoteCluster) error
+
+	// OnSharedChannelsProfileImageSyncMsg is invoked for plugins that wish to receive synchronization messages from the
+	// Shared Channels service for which they have been invited via InviteRemote.  Each call represents one user profile
+	// image that should be synchronized. `App.GetProfileImage` can be used to fetch the image bytes.
+	//
+	// The cursor will be advanced based on the timestamp returned if no error is returned.
+	//
+	// Minimum server version: 9.5
+	OnSharedChannelsProfileImageSyncMsg(user *model.User, rc *model.RemoteCluster) error
 }

server/public/plugin/hooks_timer_layer_generated.go

@@ -270,3 +270,17 @@ func (hooks *hooksTimerLayer) PreferencesHaveChanged(c *Context, preferences []m
 	hooks.hooksImpl.PreferencesHaveChanged(c, preferences)
 	hooks.recordTime(startTime, "PreferencesHaveChanged", true)
 }
+
+func (hooks *hooksTimerLayer) OnSharedChannelsAttachmentSyncMsg(fi *model.FileInfo, post *model.Post, rc *model.RemoteCluster) error {
+	startTime := timePkg.Now()
+	_returnsA := hooks.hooksImpl.OnSharedChannelsAttachmentSyncMsg(fi, post, rc)
+	hooks.recordTime(startTime, "OnSharedChannelsAttachmentSyncMsg", _returnsA == nil)
+	return _returnsA
+}
+
+func (hooks *hooksTimerLayer) OnSharedChannelsProfileImageSyncMsg(user *model.User, rc *model.RemoteCluster) error {
+	startTime := timePkg.Now()
+	_returnsA := hooks.hooksImpl.OnSharedChannelsProfileImageSyncMsg(user, rc)
+	hooks.recordTime(startTime, "OnSharedChannelsProfileImageSyncMsg", _returnsA == nil)
+	return _returnsA
+}

server/public/plugin/plugintest/hooks.go

@@ -311,6 +311,20 @@ func (_m *Hooks) OnSendDailyTelemetry() {
 	_m.Called()
 }
 
+// OnSharedChannelsAttachmentSyncMsg provides a mock function with given fields: fi, post, rc
+func (_m *Hooks) OnSharedChannelsAttachmentSyncMsg(fi *model.FileInfo, post *model.Post, rc *model.RemoteCluster) error {
+	ret := _m.Called(fi, post, rc)
+
+	var r0 error
+	if rf, ok := ret.Get(0).(func(*model.FileInfo, *model.Post, *model.RemoteCluster) error); ok {
+		r0 = rf(fi, post, rc)
+	} else {
+		r0 = ret.Error(0)
+	}
+
+	return r0
+}
+
 // OnSharedChannelsPing provides a mock function with given fields: rc
 func (_m *Hooks) OnSharedChannelsPing(rc *model.RemoteCluster) bool {
 	ret := _m.Called(rc)
@@ -325,6 +339,20 @@ func (_m *Hooks) OnSharedChannelsPing(rc *model.RemoteCluster) bool {
 	return r0
 }
 
+// OnSharedChannelsProfileImageSyncMsg provides a mock function with given fields: user, rc
+func (_m *Hooks) OnSharedChannelsProfileImageSyncMsg(user *model.User, rc *model.RemoteCluster) error {
+	ret := _m.Called(user, rc)
+
+	var r0 error
+	if rf, ok := ret.Get(0).(func(*model.User, *model.RemoteCluster) error); ok {
+		r0 = rf(user, rc)
+	} else {
+		r0 = ret.Error(0)
+	}
+
+	return r0
+}
+
 // OnSharedChannelsSyncMsg provides a mock function with given fields: msg, rc
 func (_m *Hooks) OnSharedChannelsSyncMsg(msg *model.SyncMsg, rc *model.RemoteCluster) (model.SyncResponse, error) {
 	ret := _m.Called(msg, rc)

server/public/plugin/product_hooks_generated.go

@@ -151,6 +151,14 @@ type PreferencesHaveChangedIFace interface {
 	PreferencesHaveChanged(c *Context, preferences []model.Preference)
 }
 
+type OnSharedChannelsAttachmentSyncMsgIFace interface {
+	OnSharedChannelsAttachmentSyncMsg(fi *model.FileInfo, post *model.Post, rc *model.RemoteCluster) error
+}
+
+type OnSharedChannelsProfileImageSyncMsgIFace interface {
+	OnSharedChannelsProfileImageSyncMsg(user *model.User, rc *model.RemoteCluster) error
+}
+
 type HooksAdapter struct {
 	implemented  map[int]struct{}
 	productHooks any
@@ -470,6 +478,24 @@ func NewAdapter(productHooks any) (*HooksAdapter, error) {
 		return nil, errors.New("hook has PreferencesHaveChanged method but does not implement plugin.PreferencesHaveChanged interface")
 	}
 
+	// Assessing the type of the productHooks if it individually implements OnSharedChannelsAttachmentSyncMsg interface.
+	tt = reflect.TypeOf((*OnSharedChannelsAttachmentSyncMsgIFace)(nil)).Elem()
+
+	if ft.Implements(tt) {
+		a.implemented[OnSharedChannelsAttachmentSyncMsgID] = struct{}{}
+	} else if _, ok := ft.MethodByName("OnSharedChannelsAttachmentSyncMsg"); ok {
+		return nil, errors.New("hook has OnSharedChannelsAttachmentSyncMsg method but does not implement plugin.OnSharedChannelsAttachmentSyncMsg interface")
+	}
+
+	// Assessing the type of the productHooks if it individually implements OnSharedChannelsProfileImageSyncMsg interface.
+	tt = reflect.TypeOf((*OnSharedChannelsProfileImageSyncMsgIFace)(nil)).Elem()
+
+	if ft.Implements(tt) {
+		a.implemented[OnSharedChannelsProfileImageSyncMsgID] = struct{}{}
+	} else if _, ok := ft.MethodByName("OnSharedChannelsProfileImageSyncMsg"); ok {
+		return nil, errors.New("hook has OnSharedChannelsProfileImageSyncMsg method but does not implement plugin.OnSharedChannelsProfileImageSyncMsg interface")
+	}
+
 	return a, nil
 }
 
@@ -778,3 +804,21 @@ func (a *HooksAdapter) PreferencesHaveChanged(c *Context, preferences []model.Pr
 	a.productHooks.(PreferencesHaveChangedIFace).PreferencesHaveChanged(c, preferences)
 
 }
+
+func (a *HooksAdapter) OnSharedChannelsAttachmentSyncMsg(fi *model.FileInfo, post *model.Post, rc *model.RemoteCluster) error {
+	if _, ok := a.implemented[OnSharedChannelsAttachmentSyncMsgID]; !ok {
+		panic("product hooks must implement OnSharedChannelsAttachmentSyncMsg")
+	}
+
+	return a.productHooks.(OnSharedChannelsAttachmentSyncMsgIFace).OnSharedChannelsAttachmentSyncMsg(fi, post, rc)
+
+}
+
+func (a *HooksAdapter) OnSharedChannelsProfileImageSyncMsg(user *model.User, rc *model.RemoteCluster) error {
+	if _, ok := a.implemented[OnSharedChannelsProfileImageSyncMsgID]; !ok {
+		panic("product hooks must implement OnSharedChannelsProfileImageSyncMsg")
+	}
+
+	return a.productHooks.(OnSharedChannelsProfileImageSyncMsgIFace).OnSharedChannelsProfileImageSyncMsg(user, rc)
+
+}