Adds logical deletes to shared channel remotes and remote clusters (#28159)

* Adds logical deletes to shared channel remotes and remote clusters

Instead of physically deleting the shared channel remote and remote
clusters records when a channel is unshared, a remote uninvited or a
remote cluster is deleted, now those have a logical `DeleteAt` field
that is set.

This allows us to safely restore shared channels between two remote
clusters (as of now resetting the cursor without backfilling their
contents) and to know which connections were established in the past
and now are severed.

* Delete the index in remoteclusters before adding the new column

* Fix bad error check

api/v4/source/definitions.yaml

@@ -3505,6 +3505,9 @@ components:
         create_at:
           description: Time in milliseconds that the remote cluster was created
           type: integer
+        delete_at:
+          description: Time in milliseconds that the remote cluster record was deleted
+          type: integer
         last_ping_at:
           description: Time in milliseconds when the last ping to the remote cluster was run
           type: integer
@@ -3553,6 +3556,9 @@ components:
         update_at:
           description: Time in milliseconds that the shared channel remote record was last updated
           type: integer
+        delete_at:
+          description: Time in milliseconds that the shared chanenl remote record was deleted
+          type: integer
         is_invite_accepted:
           description: Indicates if the invite has been accepted by the remote
           type: boolean

api/v4/source/remoteclusters.yaml

@@ -50,6 +50,11 @@
           description: Select only remote clusters that don't belong to a plugin
           schema:
             type: boolean
+        - name: include_deleted
+          in: query
+          description: Include those remote clusters that have been deleted
+          schema:
+            type: boolean
       responses:
         "200":
           description: Remote clusters fetch successful. Result might be empty.

api/v4/source/sharedchannels.yaml

@@ -75,6 +75,11 @@
           description: Show only those Shared channel remotes that were shared from this server
           schema:
             type: boolean
+        - name: include_deleted
+          in: query
+          description: Include those Shared channel remotes that have been deleted
+          schema:
+            type: boolean
         - name: page
           in: query
           description: The page to select

server/channels/api4/remote_cluster.go

@@ -325,6 +325,7 @@ func getRemoteClusters(c *Context, w http.ResponseWriter, r *http.Request) {
 		PluginID:       c.Params.PluginId,
 		OnlyPlugins:    c.Params.OnlyPlugins,
 		ExcludePlugins: c.Params.ExcludePlugins,
+		IncludeDeleted: c.Params.IncludeDeleted,
 	}
 
 	rcs, appErr := c.App.GetAllRemoteClusters(c.Params.Page, c.Params.PerPage, filter)

server/channels/api4/remote_cluster_test.go

@@ -5,7 +5,6 @@ package api4
 
 import (
 	"context"
-	"database/sql"
 	"encoding/base64"
 	"testing"
 
@@ -48,6 +47,13 @@ func TestGetRemoteClusters(t *testing.T) {
 			CreatorId: th.SystemAdminUser.Id,
 			PluginID:  model.NewId(),
 		},
+		{
+			RemoteId:  model.NewId(),
+			Name:      "remote4",
+			SiteURL:   "http://example4.com",
+			CreatorId: th.SystemAdminUser.Id,
+			DeleteAt:  123,
+		},
 	}
 
 	for _, rc := range newRCs {
@@ -94,6 +100,16 @@ func TestGetRemoteClusters(t *testing.T) {
 			ExpectedError:      false,
 			ExpectedNames:      []string{"remote1", "remote2", "remote3"},
 		},
+		{
+			Name:               "Should return all remote clusters including deleted",
+			Client:             th.SystemAdminClient,
+			Page:               0,
+			PerPage:            999999,
+			Filter:             model.RemoteClusterQueryFilter{IncludeDeleted: true},
+			ExpectedStatusCode: 200,
+			ExpectedError:      false,
+			ExpectedNames:      []string{"remote1", "remote2", "remote3", "remote4"},
+		},
 		{
 			Name:               "Should return all remote clusters but those belonging to plugins",
 			Client:             th.SystemAdminClient,
@@ -104,6 +120,16 @@ func TestGetRemoteClusters(t *testing.T) {
 			ExpectedError:      false,
 			ExpectedNames:      []string{"remote1", "remote2"},
 		},
+		{
+			Name:               "Should return all remote clusters but those belonging to plugins, including deleted",
+			Client:             th.SystemAdminClient,
+			Page:               0,
+			PerPage:            999999,
+			Filter:             model.RemoteClusterQueryFilter{ExcludePlugins: true, IncludeDeleted: true},
+			ExpectedStatusCode: 200,
+			ExpectedError:      false,
+			ExpectedNames:      []string{"remote1", "remote2", "remote4"},
+		},
 		{
 			Name:               "Should return only remote clusters belonging to plugins",
 			Client:             th.SystemAdminClient,
@@ -572,18 +598,19 @@ func TestDeleteRemoteCluster(t *testing.T) {
 	})
 
 	t.Run("should correctly delete the remote cluster", func(t *testing.T) {
+		// ensure the remote cluster is not deleted
+		initialRC, appErr := th.App.GetRemoteCluster(rc.RemoteId)
+		require.Nil(t, appErr)
+		require.NotEmpty(t, initialRC)
+		require.Zero(t, initialRC.DeleteAt)
+
 		resp, err := th.SystemAdminClient.DeleteRemoteCluster(context.Background(), rc.RemoteId)
 		CheckNoContentStatus(t, resp)
 		require.NoError(t, err)
 
-		deletedRC, err := th.App.GetRemoteCluster(rc.RemoteId)
+		deletedRC, appErr := th.App.GetRemoteCluster(rc.RemoteId)
-		require.ErrorIs(t, err, sql.ErrNoRows)
+		require.Nil(t, appErr)
-		require.Empty(t, deletedRC)
+		require.NotEmpty(t, deletedRC)
-	})
+		require.NotZero(t, deletedRC.DeleteAt)
-
-	t.Run("should return not found if the remote cluster is already deleted", func(t *testing.T) {
-		resp, err := th.SystemAdminClient.DeleteRemoteCluster(context.Background(), rc.RemoteId)
-		CheckNotFoundStatus(t, resp)
-		require.Error(t, err)
 	})
 }

server/channels/api4/shared_channel.go

@@ -119,6 +119,7 @@ func getSharedChannelRemotesByRemoteCluster(c *Context, w http.ResponseWriter, r
 		RemoteId:       c.Params.RemoteId,
 		ExcludeHome:    c.Params.ExcludeHome,
 		ExcludeRemote:  c.Params.ExcludeRemote,
+		IncludeDeleted: c.Params.IncludeDeleted,
 	}
 	sharedChannelRemotes, err := c.App.GetSharedChannelRemotes(c.Params.Page, c.Params.PerPage, filter)
 	if err != nil {
@@ -153,7 +154,7 @@ func inviteRemoteClusterToChannel(c *Context, w http.ResponseWriter, r *http.Req
 		return
 	}
 
-	if _, appErr := c.App.GetRemoteCluster(c.Params.RemoteId); appErr != nil {
+	if rc, appErr := c.App.GetRemoteCluster(c.Params.RemoteId); appErr != nil || rc.DeleteAt != 0 {
 		c.SetInvalidRemoteIdError(c.Params.RemoteId)
 		return
 	}
@@ -200,7 +201,7 @@ func uninviteRemoteClusterToChannel(c *Context, w http.ResponseWriter, r *http.R
 		return
 	}
 
-	if _, appErr := c.App.GetRemoteCluster(c.Params.RemoteId); appErr != nil {
+	if rc, appErr := c.App.GetRemoteCluster(c.Params.RemoteId); appErr != nil || rc.DeleteAt != 0 {
 		c.SetInvalidRemoteIdError(c.Params.RemoteId)
 		return
 	}

server/channels/api4/shared_channel_test.go

@@ -299,6 +299,20 @@ func TestGetSharedChannelRemotesByRemoteCluster(t *testing.T) {
 	_, err = th.App.ShareChannel(th.Context, sc3)
 	require.NoError(t, err)
 
+	c4 := th.CreateChannelWithClientAndTeam(th.Client, model.ChannelTypeOpen, th.BasicTeam.Id)
+	sc4 := &model.SharedChannel{
+		ChannelId:        c4.Id,
+		TeamId:           th.BasicTeam.Id,
+		ShareName:        "shared_4",
+		ShareDisplayName: "Shared Channel 4",
+		CreatorId:        th.BasicUser.Id,
+		RemoteId:         rc1.RemoteId,
+		Home:             false,
+	}
+
+	_, err = th.App.ShareChannel(th.Context, sc4)
+	require.NoError(t, err)
+
 	// for the pagination test, we need to get the channelId of the
 	// second SharedChannelRemote that belongs to RC1, sorted by ID,
 	// so we accumulate those SharedChannelRemotes on creation and
@@ -307,7 +321,7 @@ func TestGetSharedChannelRemotesByRemoteCluster(t *testing.T) {
 	sharedChannelRemotesFromRC1 := []*model.SharedChannelRemote{}
 
 	// create the shared channel remotes
-	for _, sc := range []*model.SharedChannel{sc1, sc2, sc3} {
+	for _, sc := range []*model.SharedChannel{sc1, sc2, sc3, sc4} {
 		scr := &model.SharedChannelRemote{
 			Id:                model.NewId(),
 			ChannelId:         sc.ChannelId,
@@ -324,6 +338,14 @@ func TestGetSharedChannelRemotesByRemoteCluster(t *testing.T) {
 		}
 	}
 
+	// we delete the shared channel remote for sc4
+	scr4, err := th.App.GetSharedChannelRemoteByIds(sc4.ChannelId, sc4.RemoteId)
+	require.NoError(t, err)
+
+	deleted, err := th.App.DeleteSharedChannelRemote(scr4.Id)
+	require.NoError(t, err)
+	require.True(t, deleted)
+
 	sort.Slice(sharedChannelRemotesFromRC1, func(i, j int) bool {
 		return sharedChannelRemotesFromRC1[i].Id < sharedChannelRemotesFromRC1[j].Id
 	})
@@ -335,6 +357,7 @@ func TestGetSharedChannelRemotesByRemoteCluster(t *testing.T) {
 			RemoteId           string
 			ExcludeHome        bool
 			ExcludeRemote      bool
+			IncludeDeleted     bool
 			Page               int
 			PerPage            int
 			ExpectedStatusCode int
@@ -369,6 +392,17 @@ func TestGetSharedChannelRemotesByRemoteCluster(t *testing.T) {
 				ExpectedError:      false,
 				ExpectedIds:        []string{sc1.ChannelId, sc2.ChannelId},
 			},
+			{
+				Name:               "should return the complete list of shared channel remotes for a remote cluster, including deleted",
+				Client:             th.SystemAdminClient,
+				RemoteId:           rc1.RemoteId,
+				IncludeDeleted:     true,
+				Page:               0,
+				PerPage:            100,
+				ExpectedStatusCode: http.StatusOK,
+				ExpectedError:      false,
+				ExpectedIds:        []string{sc1.ChannelId, sc2.ChannelId, sc4.ChannelId},
+			},
 			{
 				Name:               "should return only the shared channel remotes homed localy",
 				Client:             th.SystemAdminClient,
@@ -395,6 +429,7 @@ func TestGetSharedChannelRemotesByRemoteCluster(t *testing.T) {
 				Name:               "should correctly paginate the results",
 				Client:             th.SystemAdminClient,
 				RemoteId:           rc1.RemoteId,
+				IncludeDeleted:     true,
 				Page:               1,
 				PerPage:            1,
 				ExpectedStatusCode: http.StatusOK,
@@ -405,7 +440,7 @@ func TestGetSharedChannelRemotesByRemoteCluster(t *testing.T) {
 
 		for _, tc := range testCases {
 			t.Run(tc.Name, func(t *testing.T) {
-				scrs, resp, err := tc.Client.GetSharedChannelRemotesByRemoteCluster(context.Background(), tc.RemoteId, tc.ExcludeHome, tc.ExcludeRemote, tc.Page, tc.PerPage)
+				scrs, resp, err := tc.Client.GetSharedChannelRemotesByRemoteCluster(context.Background(), tc.RemoteId, tc.ExcludeHome, tc.ExcludeRemote, tc.IncludeDeleted, tc.Page, tc.PerPage)
 				checkHTTPStatus(t, resp, tc.ExpectedStatusCode)
 				if tc.ExpectedError {
 					require.Error(t, err)

server/channels/app/remote_cluster.go

@@ -30,10 +30,20 @@ func (a *App) RegisterPluginForSharedChannels(rctx request.CTX, opts model.Regis
 
 	// if plugin is already registered then treat this as an update.
 	if rc != nil {
+		// plugin was deleted at some point
+		if rc.DeleteAt != 0 {
+			rctx.Logger().Debug("Restoring plugin registration for Shared Channels",
+				mlog.String("plugin_id", opts.PluginID),
+				mlog.String("remote_id", rc.RemoteId),
+			)
+
+			rc.DeleteAt = 0
+		} else {
 			rctx.Logger().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()
@@ -82,6 +92,11 @@ func (a *App) UnregisterPluginForSharedChannels(pluginID string) error {
 		return err
 	}
 
+	if rc.DeleteAt != 0 {
+		// plugin already unregistered, nothing to do
+		return nil
+	}
+
 	_, appErr := a.DeleteRemoteCluster(rc.RemoteId)
 	if appErr != nil {
 		return appErr

server/channels/app/remote_cluster_test.go

@@ -6,11 +6,9 @@ package app
 import (
 	"testing"
 
-	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
 
 	"github.com/mattermost/mattermost/server/public/model"
-	"github.com/mattermost/mattermost/server/public/shared/i18n"
 )
 
 func setupRemoteCluster(tb testing.TB) *TestHelper {
@@ -38,8 +36,7 @@ func TestAddRemoteCluster(t *testing.T) {
 
 		remoteCluster.RemoteId = model.NewId()
 		_, err = th.App.AddRemoteCluster(remoteCluster)
-		require.NotNil(t, err, "Adding a duplicate remote cluster should error")
+		require.Nil(t, err, "Adding a duplicate remote cluster should work fine")
-		assert.Contains(t, err.Error(), i18n.T("api.remote_cluster.save_not_unique.app_error"))
 	})
 }
 
@@ -74,8 +71,7 @@ func TestUpdateRemoteCluster(t *testing.T) {
 
 		savedRemoteClustered.SiteURL = remoteCluster.SiteURL
 		_, err = th.App.UpdateRemoteCluster(savedRemoteClustered)
-		require.NotNil(t, err, "Updating remote cluster with duplicate site url should error")
+		require.Nil(t, err, "Updating remote cluster with duplicate site url should work fine")
-		assert.Contains(t, err.Error(), i18n.T("api.remote_cluster.update_not_unique.app_error"))
 	})
 
 	t.Run("update remote cluster with an already existing site url, is not allowed", func(t *testing.T) {
@@ -106,7 +102,6 @@ func TestUpdateRemoteCluster(t *testing.T) {
 		// Same site url
 		anotherExistingRemoteClustered.SiteURL = existingRemoteCluster.SiteURL
 		_, err = th.App.UpdateRemoteCluster(anotherExistingRemoteClustered)
-		require.NotNil(t, err, "Updating remote cluster should error")
+		require.Nil(t, err, "Updating remote cluster should work fine")
-		assert.Contains(t, err.Error(), i18n.T("api.remote_cluster.update_not_unique.app_error"))
 	})
 }

server/channels/app/session.go

@@ -69,7 +69,7 @@ func (a *App) GetCloudSession(token string) (*model.Session, *model.AppError) {
 
 func (a *App) GetRemoteClusterSession(token string, remoteId string) (*model.Session, *model.AppError) {
 	rc, appErr := a.GetRemoteCluster(remoteId)
-	if appErr == nil && subtle.ConstantTimeCompare([]byte(rc.Token), []byte(token)) == 1 {
+	if appErr == nil && rc.DeleteAt == 0 && subtle.ConstantTimeCompare([]byte(rc.Token), []byte(token)) == 1 {
 		// Need a bare-bones session object for later checks
 		session := &model.Session{
 			Token:   token,

server/channels/app/slashcommands/command_remote.go

@@ -219,7 +219,7 @@ func (rp *RemoteProvider) doRemove(a *app.App, args *model.CommandArgs, margs ma
 
 // doStatus displays connection status for all remote clusters.
 func (rp *RemoteProvider) doStatus(a *app.App, args *model.CommandArgs, _ map[string]string) *model.CommandResponse {
-	list, err := a.GetAllRemoteClusters(0, 999999, model.RemoteClusterQueryFilter{})
+	list, err := a.GetAllRemoteClusters(0, 999999, model.RemoteClusterQueryFilter{IncludeDeleted: true})
 	if err != nil {
 		responsef(args.T("api.command_remote.fetch_status.error", map[string]any{"Error": err.Error()}))
 	}
@@ -230,15 +230,16 @@ func (rp *RemoteProvider) doStatus(a *app.App, args *model.CommandArgs, _ map[st
 
 	var sb strings.Builder
 	fmt.Fprintf(&sb, args.T("api.command_remote.remote_table_header")+" \n")
-	// | Secure Connection | Display name | ConnectionID | Site URL | Invite accepted | Online | Last ping  |
+	// | Secure Connection | Display name | ConnectionID | Site URL | Default Team | Invite accepted | Online | Last ping | Deleted |
-	fmt.Fprintf(&sb, "| :---- | :---- | :---- | :---- | :---- | :---- | :---- | \n")
+	fmt.Fprintf(&sb, "| :---- | :---- | :---- | :---- | :---- | :---- | :---- | :---- | | :---- |\n")
 
 	for _, rc := range list {
 		accepted := formatBool(args.T, rc.IsConfirmed())
 		online := formatBool(args.T, isOnline(rc.LastPingAt))
 		lastPing := formatTimestamp(rc.LastPingAt)
+		deleted := formatBool(args.T, rc.DeleteAt != 0)
 
-		fmt.Fprintf(&sb, "| %s | %s | %s | %s | %s | %s | %s |\n", rc.Name, rc.DisplayName, rc.RemoteId, rc.GetSiteURL(), accepted, online, lastPing)
+		fmt.Fprintf(&sb, "| %s | %s | %s | %s | %s | %s | %s | %s | %s |\n", rc.Name, rc.DisplayName, rc.RemoteId, rc.GetSiteURL(), rc.DefaultTeamId, accepted, online, lastPing, deleted)
 	}
 	return responsef(sb.String())
 }

server/channels/app/slashcommands/command_share.go

@@ -252,6 +252,9 @@ func (sp *ShareProvider) doInviteRemote(a *app.App, c request.CTX, args *model.C
 	if appErr != nil {
 		return responsef(args.T("api.command_share.remote_id_invalid.error", map[string]any{"Error": appErr.Error()}))
 	}
+	if rc.DeleteAt != 0 {
+		return responsef(args.T("api.command_share.remote_id_invalid.error", map[string]any{"Error": "entity is deleted"}))
+	}
 
 	if err = a.InviteRemoteToChannel(args.ChannelId, remoteID, args.UserId, true); err != nil {
 		return responsef(args.T("api.command_share.invite_remote_to_channel.error", map[string]any{"Error": err.Error()}))

server/channels/db/migrations/migrations.list

@@ -247,6 +247,8 @@ channels/db/migrations/mysql/000124_remove_manage_team_permission.down.sql
 channels/db/migrations/mysql/000124_remove_manage_team_permission.up.sql
 channels/db/migrations/mysql/000125_remoteclusters_add_default_team_id.down.sql
 channels/db/migrations/mysql/000125_remoteclusters_add_default_team_id.up.sql
+channels/db/migrations/mysql/000126_sharedchannels_remotes_add_deleteat.down.sql
+channels/db/migrations/mysql/000126_sharedchannels_remotes_add_deleteat.up.sql
 channels/db/migrations/postgres/000001_create_teams.down.sql
 channels/db/migrations/postgres/000001_create_teams.up.sql
 channels/db/migrations/postgres/000002_create_team_members.down.sql
@@ -495,3 +497,5 @@ channels/db/migrations/postgres/000124_remove_manage_team_permission.down.sql
 channels/db/migrations/postgres/000124_remove_manage_team_permission.up.sql
 channels/db/migrations/postgres/000125_remoteclusters_add_default_team_id.down.sql
 channels/db/migrations/postgres/000125_remoteclusters_add_default_team_id.up.sql
+channels/db/migrations/postgres/000126_sharedchannels_remotes_add_deleteat.down.sql
+channels/db/migrations/postgres/000126_sharedchannels_remotes_add_deleteat.up.sql

server/channels/db/migrations/mysql/000126_sharedchannels_remotes_add_deleteat.down.sql

@@ -0,0 +1 @@
+-- Skipping it because the forward migrations are destructive

server/channels/db/migrations/mysql/000126_sharedchannels_remotes_add_deleteat.up.sql

@@ -0,0 +1,44 @@
+SET @preparedStatement = (SELECT IF(
+    (
+        SELECT COUNT(*) FROM INFORMATION_SCHEMA.STATISTICS
+        WHERE table_name = 'RemoteClusters'
+        AND table_schema = DATABASE()
+        AND index_name = 'remote_clusters_site_url_unique'
+    ) > 0,
+    'DROP INDEX remote_clusters_site_url_unique ON RemoteClusters;',
+    'SELECT 1'
+));
+
+PREPARE removeIndexIfExists FROM @preparedStatement;
+EXECUTE removeIndexIfExists;
+DEALLOCATE PREPARE removeIndexIfExists;
+
+SET @preparedStatement = (SELECT IF(
+    (
+        SELECT COUNT(*) FROM INFORMATION_SCHEMA.COLUMNS
+        WHERE table_name = 'RemoteClusters'
+        AND table_schema = DATABASE()
+        AND column_name = 'DeleteAt'
+    ) > 0,
+    'SELECT 1',
+    'ALTER TABLE RemoteClusters ADD DeleteAt bigint(20) DEFAULT 0;'
+));
+
+PREPARE alterIfNotExists FROM @preparedStatement;
+EXECUTE alterIfNotExists;
+DEALLOCATE PREPARE alterIfNotExists;
+
+SET @preparedStatement = (SELECT IF(
+    (
+        SELECT COUNT(*) FROM INFORMATION_SCHEMA.COLUMNS
+        WHERE table_name = 'SharedChannelRemotes'
+        AND table_schema = DATABASE()
+        AND column_name = 'DeleteAt'
+    ) > 0,
+    'SELECT 1',
+    'ALTER TABLE SharedChannelRemotes ADD DeleteAt bigint(20) DEFAULT 0;'
+));
+
+PREPARE alterIfNotExists FROM @preparedStatement;
+EXECUTE alterIfNotExists;
+DEALLOCATE PREPARE alterIfNotExists;

server/channels/db/migrations/postgres/000126_sharedchannels_remotes_add_deleteat.down.sql

@@ -0,0 +1 @@
+-- Skipping it because the forward migrations are destructive

server/channels/db/migrations/postgres/000126_sharedchannels_remotes_add_deleteat.up.sql

@@ -0,0 +1,4 @@
+DROP INDEX IF EXISTS remote_clusters_site_url_unique;
+ALTER TABLE remoteclusters ADD COLUMN IF NOT EXISTS deleteat bigint DEFAULT 0;
+
+ALTER TABLE sharedchannelremotes ADD COLUMN IF NOT EXISTS deleteat bigint DEFAULT 0;

server/channels/store/sqlstore/remote_cluster_store.go

@@ -36,6 +36,7 @@ func remoteClusterFields(prefix string) []string {
 		prefix + "SiteURL",
 		prefix + "DefaultTeamId",
 		prefix + "CreateAt",
+		prefix + "DeleteAt",
 		prefix + "LastPingAt",
 		prefix + "Token",
 		prefix + "RemoteToken",
@@ -67,10 +68,10 @@ func (s sqlRemoteClusterStore) Save(remoteCluster *model.RemoteCluster) (*model.
 
 	query := `INSERT INTO RemoteClusters
 				(RemoteId, RemoteTeamId, Name, DisplayName, SiteURL, DefaultTeamId, CreateAt,
-				LastPingAt, Token, RemoteToken, Topics, CreatorId, PluginID, Options)
+                DeleteAt, LastPingAt, Token, RemoteToken, Topics, CreatorId, PluginID, Options)
 				VALUES
 				(:RemoteId, :RemoteTeamId, :Name, :DisplayName, :SiteURL, :DefaultTeamId, :CreateAt,
-				:LastPingAt, :Token, :RemoteToken, :Topics, :CreatorId, :PluginID, :Options)`
+				:DeleteAt, :LastPingAt, :Token, :RemoteToken, :Topics, :CreatorId, :PluginID, :Options)`
 
 	if _, err := s.GetMasterX().NamedExec(query, remoteCluster); err != nil {
 		return nil, errors.Wrap(err, "failed to save RemoteCluster")
@@ -89,6 +90,7 @@ func (s sqlRemoteClusterStore) Update(remoteCluster *model.RemoteCluster) (*mode
 			SET Token = :Token,
 			RemoteTeamId = :RemoteTeamId,
 			CreateAt = :CreateAt,
+            DeleteAt = :DeleteAt,
 			LastPingAt = :LastPingAt,
 			RemoteToken = :RemoteToken,
 			CreatorId = :CreatorId,
@@ -107,24 +109,53 @@ func (s sqlRemoteClusterStore) Update(remoteCluster *model.RemoteCluster) (*mode
 }
 
 func (s sqlRemoteClusterStore) Delete(remoteId string) (bool, error) {
+	transaction, err := s.GetMasterX().Beginx()
+	if err != nil {
+		return false, errors.Wrap(err, "DeleteRemoteCluster: begin_transaction")
+	}
+	defer finalizeTransactionX(transaction, &err)
+
+	curTime := model.GetMillis()
+
+	// we delete the remote cluster itself
 	squery, args, err := s.getQueryBuilder().
-		Delete("RemoteClusters").
+		Update("RemoteClusters").
+		Set("DeleteAt", curTime).
 		Where(sq.Eq{"RemoteId": remoteId}).
 		ToSql()
 	if err != nil {
 		return false, errors.Wrap(err, "delete_remote_cluster_tosql")
 	}
 
-	result, err := s.GetMasterX().Exec(squery, args...)
+	result, err := transaction.Exec(squery, args...)
 	if err != nil {
 		return false, errors.Wrap(err, "failed to delete RemoteCluster")
 	}
 
+	// also remove the shared channel remotes for the cluster (if any)
+	squery, args, err = s.getQueryBuilder().
+		Update("SharedChannelRemotes").
+		Set("UpdateAt", curTime).
+		Set("DeleteAt", curTime).
+		Where(sq.Eq{"RemoteId": remoteId}).
+		ToSql()
+	if err != nil {
+		return false, errors.Wrap(err, "delete_shared_channel_remotes_for_remote_cluster_tosql")
+	}
+
+	if _, err = transaction.Exec(squery, args...); err != nil {
+		return false, errors.Wrap(err, "failed to delete SharedChannelRemotes for RemoteCluster")
+	}
+
 	count, err := result.RowsAffected()
 	if err != nil {
 		return false, errors.Wrap(err, "failed to determine rows affected")
 	}
 
+	if err = transaction.Commit(); err != nil {
+		return false, errors.Wrap(err, "commit_transaction")
+	}
+
 	return count > 0, nil
 }
 
@@ -213,6 +244,10 @@ func (s sqlRemoteClusterStore) GetAll(offset, limit int, filter model.RemoteClus
 		query = query.Where(sq.NotEq{fmt.Sprintf("(rc.Options & %d)", filter.RequireOptions): 0})
 	}
 
+	if !filter.IncludeDeleted {
+		query = query.Where(sq.Eq{"DeleteAt": 0})
+	}
+
 	if filter.Topic != "" {
 		trimmed := strings.TrimSpace(filter.Topic)
 		if trimmed == "" || trimmed == "*" {

server/channels/store/sqlstore/shared_channel_store.go

@@ -269,8 +269,10 @@ func (s SqlSharedChannelStore) Update(sc *model.SharedChannel) (*model.SharedCha
 	return sc, nil
 }
 
-// Delete deletes a single shared channel plus associated SharedChannelRemotes.
+// Delete deletes a single shared channel as deleted, plus marks as
-// Returns true if shared channel found and deleted, false if not found.
+// deleted associated SharedChannelRemotes.
+// Returns true if shared channel found and deleted, false if not
+// found.
 func (s SqlSharedChannelStore) Delete(channelId string) (ok bool, err error) {
 	transaction, err := s.GetMasterX().Beginx()
 	if err != nil {
@@ -291,17 +293,20 @@ func (s SqlSharedChannelStore) Delete(channelId string) (ok bool, err error) {
 		return false, errors.Wrap(err, "failed to delete SharedChannel")
 	}
 
+	curTime := model.GetMillis()
+
 	// Also remove remotes from SharedChannelRemotes (if any).
 	squery, args, err = s.getQueryBuilder().
-		Delete("SharedChannelRemotes").
+		Update("SharedChannelRemotes").
+		Set("UpdateAt", curTime).
+		Set("DeleteAt", curTime).
 		Where(sq.Eq{"ChannelId": channelId}).
 		ToSql()
 	if err != nil {
 		return false, errors.Wrap(err, "delete_shared_channel_remotes_tosql")
 	}
 
-	_, err = transaction.Exec(squery, args...)
+	if _, err = transaction.Exec(squery, args...); err != nil {
-	if err != nil {
 		return false, errors.Wrap(err, "failed to delete SharedChannelRemotes")
 	}
 
@@ -337,10 +342,10 @@ func (s SqlSharedChannelStore) SaveRemote(remote *model.SharedChannelRemote) (*m
 	}
 
 	query, args, err := s.getQueryBuilder().Insert("SharedChannelRemotes").
-		Columns("Id", "ChannelId", "CreatorId", "CreateAt", "UpdateAt", "IsInviteAccepted", "IsInviteConfirmed", "RemoteId",
+		Columns("Id", "ChannelId", "CreatorId", "CreateAt", "UpdateAt", "DeleteAt", "IsInviteAccepted", "IsInviteConfirmed", "RemoteId",
 			"LastPostCreateAt", "LastPostCreateId", "LastPostUpdateAt", "LastPostId").
-		Values(remote.Id, remote.ChannelId, remote.CreatorId, remote.CreateAt, remote.UpdateAt, remote.IsInviteAccepted, remote.IsInviteConfirmed, remote.RemoteId,
+		Values(remote.Id, remote.ChannelId, remote.CreatorId, remote.CreateAt, remote.UpdateAt, remote.DeleteAt, remote.IsInviteAccepted, remote.IsInviteConfirmed,
-			remote.LastPostCreateAt, remote.LastPostCreateID, remote.LastPostUpdateAt, remote.LastPostUpdateID).
+			remote.RemoteId, remote.LastPostCreateAt, remote.LastPostCreateID, remote.LastPostUpdateAt, remote.LastPostUpdateID).
 		ToSql()
 	if err != nil {
 		return nil, errors.Wrapf(err, "savesharedchannelremote_tosql")
@@ -362,6 +367,7 @@ func (s SqlSharedChannelStore) UpdateRemote(remote *model.SharedChannelRemote) (
 		Set("CreatorId", remote.CreatorId).
 		Set("CreateAt", remote.CreateAt).
 		Set("UpdateAt", remote.UpdateAt).
+		Set("DeleteAt", remote.DeleteAt).
 		Set("IsInviteAccepted", remote.IsInviteAccepted).
 		Set("IsInviteConfirmed", remote.IsInviteConfirmed).
 		Set("RemoteId", remote.RemoteId).
@@ -403,6 +409,7 @@ func sharedChannelRemoteFields(prefix string) []string {
 		prefix + "CreatorId",
 		prefix + "CreateAt",
 		prefix + "UpdateAt",
+		prefix + "DeleteAt",
 		prefix + "IsInviteAccepted",
 		prefix + "IsInviteConfirmed",
 		prefix + "RemoteId",
@@ -504,6 +511,10 @@ func (s SqlSharedChannelStore) GetRemotes(offset, limit int, opts model.SharedCh
 
 	query = query.Offset(uint64(offset)).Limit(uint64(limit))
 
+	if !opts.IncludeDeleted {
+		query = query.Where(sq.Eq{"DeleteAt": 0})
+	}
+
 	squery, args, err := query.ToSql()
 	if err != nil {
 		return nil, errors.Wrapf(err, "get_shared_channel_remotes_tosql")
@@ -526,6 +537,7 @@ func (s SqlSharedChannelStore) HasRemote(channelID string, remoteId string) (boo
 		From("SharedChannelRemotes").
 		Where(sq.Eq{"RemoteId": remoteId}).
 		Where(sq.Eq{"ChannelId": channelID}).
+		Where(sq.Eq{"DeleteAt": 0}).
 		Suffix(")")
 
 	query, args, err := builder.ToSql()
@@ -549,6 +561,7 @@ func (s SqlSharedChannelStore) GetRemoteForUser(remoteId string, userId string)
 		Join("SharedChannelRemotes AS scr ON rc.RemoteId = scr.RemoteId").
 		Join("ChannelMembers AS cm ON scr.ChannelId = cm.ChannelId").
 		Where(sq.Eq{"rc.RemoteId": remoteId}).
+		Where(sq.Eq{"scr.DeleteAt": 0}).
 		Where(sq.Eq{"cm.UserId": userId})
 
 	query, args, err := builder.ToSql()
@@ -614,8 +627,12 @@ func (s SqlSharedChannelStore) UpdateRemoteCursor(id string, cursor model.GetPos
 // DeleteRemote deletes a single shared channel remote.
 // Returns true if remote found and deleted, false if not found.
 func (s SqlSharedChannelStore) DeleteRemote(id string) (bool, error) {
+	curTime := model.GetMillis()
+
 	squery, args, err := s.getQueryBuilder().
-		Delete("SharedChannelRemotes").
+		Update("SharedChannelRemotes").
+		Set("DeleteAt", curTime).
+		Set("UpdateAt", curTime).
 		Where(sq.Eq{"Id": id}).
 		ToSql()
 	if err != nil {
@@ -644,6 +661,7 @@ func (s SqlSharedChannelStore) GetRemotesStatus(channelId string) ([]*model.Shar
 		Select("scr.ChannelId, rc.DisplayName, rc.SiteURL, rc.LastPingAt, sc.ReadOnly, scr.IsInviteAccepted").
 		From("SharedChannelRemotes scr, RemoteClusters rc, SharedChannels sc").
 		Where("scr.RemoteId = rc.RemoteId").
+		Where("scr.DeleteAt = 0").
 		Where("scr.ChannelId = sc.ChannelId").
 		Where(sq.Eq{"scr.ChannelId": channelId})
 

server/channels/store/storetest/remote_cluster_store.go

@@ -145,7 +145,7 @@ func testRemoteClusterSave(t *testing.T, _ request.CTX, ss store.Store) {
 	})
 }
 
-func testRemoteClusterDelete(t *testing.T, _ request.CTX, ss store.Store) {
+func testRemoteClusterDelete(t *testing.T, rctx request.CTX, ss store.Store) {
 	t.Run("Delete", func(t *testing.T) {
 		rc := &model.RemoteCluster{
 			Name:      "shortlived_remote",
@@ -158,6 +158,57 @@ func testRemoteClusterDelete(t *testing.T, _ request.CTX, ss store.Store) {
 		deleted, err := ss.RemoteCluster().Delete(rcSaved.RemoteId)
 		require.NoError(t, err)
 		require.True(t, deleted)
+
+		deletedRC, err := ss.RemoteCluster().Get(rcSaved.RemoteId)
+		require.NoError(t, err)
+		require.NotZero(t, deletedRC.DeleteAt)
+	})
+
+	t.Run("Delete with shared channel remotes", func(t *testing.T) {
+		rc := &model.RemoteCluster{
+			Name:      "shortlived_remote",
+			SiteURL:   makeSiteURL(),
+			CreatorId: model.NewId(),
+		}
+		rcSaved, err := ss.RemoteCluster().Save(rc)
+		require.NoError(t, err)
+
+		// we create a shared channel remote for the remote cluster
+		channel, err := createTestChannel(ss, rctx, "test_delete")
+		require.NoError(t, err)
+
+		sc := &model.SharedChannel{
+			ChannelId: channel.Id,
+			TeamId:    channel.TeamId,
+			CreatorId: model.NewId(),
+			ShareName: "testshare",
+			RemoteId:  model.NewId(),
+		}
+
+		_, err = ss.SharedChannel().Save(sc)
+		require.NoError(t, err, "couldn't save shared channel", err)
+
+		scr := &model.SharedChannelRemote{
+			ChannelId: channel.Id,
+			CreatorId: model.NewId(),
+			RemoteId:  rc.RemoteId,
+		}
+		scrSaved, err := ss.SharedChannel().SaveRemote(scr)
+		require.NoError(t, err)
+
+		// and then we delete the cluster, expecting the shared
+		// channel remote to be deleted as well
+		deleted, err := ss.RemoteCluster().Delete(rcSaved.RemoteId)
+		require.NoError(t, err)
+		require.True(t, deleted)
+
+		deletedRC, err := ss.RemoteCluster().Get(rcSaved.RemoteId)
+		require.NoError(t, err)
+		require.NotZero(t, deletedRC.DeleteAt)
+
+		deletedSCR, err := ss.SharedChannel().GetRemote(scrSaved.Id)
+		require.NoError(t, err)
+		require.NotZero(t, deletedSCR.DeleteAt)
 	})
 
 	t.Run("Delete nonexistent", func(t *testing.T) {
@@ -218,7 +269,7 @@ func testRemoteClusterGetByPluginID(t *testing.T, _ request.CTX, ss store.Store)
 }
 
 func testRemoteClusterGetAll(t *testing.T, _ request.CTX, ss store.Store) {
-	require.NoError(t, clearRemoteClusters(ss))
+	ss.DropAllTables()
 
 	userId := model.NewId()
 	now := model.GetMillis()
@@ -232,9 +283,11 @@ func testRemoteClusterGetAll(t *testing.T, _ request.CTX, ss store.Store) {
 		{Name: "brand_new_offline_remote", CreatorId: userId, SiteURL: "", LastPingAt: 0, Topics: " bogus shared stuff "},
 		{Name: "offline_plugin_remote", CreatorId: model.NewId(), SiteURL: makeSiteURL(), PluginID: model.NewId(), LastPingAt: 0, Topics: " pluginshare "},
 		{Name: "online_plugin_remote", CreatorId: model.NewId(), SiteURL: makeSiteURL(), PluginID: model.NewId(), LastPingAt: now, Topics: " pluginshare "},
+		{Name: "deleted_remote", CreatorId: model.NewId(), SiteURL: "", LastPingAt: 0, DeleteAt: 123},
 	}
 
 	idsAll := make([]string, 0)
+	idsNotDeleted := make([]string, 0)
 	idsOnline := make([]string, 0)
 	idsShareTopic := make([]string, 0)
 	idsPlugin := make([]string, 0)
@@ -246,6 +299,10 @@ func testRemoteClusterGetAll(t *testing.T, _ request.CTX, ss store.Store) {
 		saved, err := ss.RemoteCluster().Save(item)
 		require.NoError(t, err)
 		idsAll = append(idsAll, saved.RemoteId)
+		if item.DeleteAt == 0 {
+			idsNotDeleted = append(idsNotDeleted, saved.RemoteId)
+
+			// only include non-deleted items in other counts
 			if online {
 				idsOnline = append(idsOnline, saved.RemoteId)
 			}
@@ -261,9 +318,10 @@ func testRemoteClusterGetAll(t *testing.T, _ request.CTX, ss store.Store) {
 				idsConfirmed = append(idsConfirmed, saved.RemoteId)
 			}
 		}
+	}
 
 	t.Run("GetAll", func(t *testing.T) {
-		filter := model.RemoteClusterQueryFilter{}
+		filter := model.RemoteClusterQueryFilter{IncludeDeleted: true}
 		remotes, err := ss.RemoteCluster().GetAll(0, 999999, filter)
 		require.NoError(t, err)
 		// make sure all the test data remotes were returned.
@@ -271,6 +329,15 @@ func testRemoteClusterGetAll(t *testing.T, _ request.CTX, ss store.Store) {
 		assert.ElementsMatch(t, ids, idsAll)
 	})
 
+	t.Run("GetAllNotDeleted", func(t *testing.T) {
+		filter := model.RemoteClusterQueryFilter{}
+		remotes, err := ss.RemoteCluster().GetAll(0, 999999, filter)
+		require.NoError(t, err)
+		// make sure all the test data remotes were returned.
+		ids := getIds(remotes)
+		assert.ElementsMatch(t, ids, idsNotDeleted)
+	})
+
 	t.Run("GetAll online only", func(t *testing.T) {
 		filter := model.RemoteClusterQueryFilter{
 			ExcludeOffline: true,
@@ -375,7 +442,7 @@ func testRemoteClusterGetAllInChannel(t *testing.T, rctx request.CTX, ss store.S
 		testPluginID_2 = "com.sample.bloop"
 	)
 
-	require.NoError(t, clearRemoteClusters(ss))
+	ss.DropAllTables()
 	now := model.GetMillis()
 
 	userId := model.NewId()
@@ -485,7 +552,7 @@ func testRemoteClusterGetAllInChannel(t *testing.T, rctx request.CTX, ss store.S
 }
 
 func testRemoteClusterGetAllNotInChannel(t *testing.T, rctx request.CTX, ss store.Store) {
-	require.NoError(t, clearRemoteClusters(ss))
+	ss.DropAllTables()
 
 	userId := model.NewId()
 
@@ -590,7 +657,7 @@ func getIds(remotes []*model.RemoteCluster) []string {
 }
 
 func testRemoteClusterGetByTopic(t *testing.T, _ request.CTX, ss store.Store) {
-	require.NoError(t, clearRemoteClusters(ss))
+	ss.DropAllTables()
 
 	rcData := []*model.RemoteCluster{
 		{Name: "AAAA_Inc", CreatorId: model.NewId(), SiteURL: "aaaa.com", RemoteId: model.NewId(), Topics: ""},
@@ -670,17 +737,3 @@ func testRemoteClusterUpdateTopics(t *testing.T, _ request.CTX, ss store.Store)
 		require.Equal(t, tt.expected, rcUpdated.Topics)
 	}
 }
-
-func clearRemoteClusters(ss store.Store) error {
-	list, err := ss.RemoteCluster().GetAll(0, 999999, model.RemoteClusterQueryFilter{})
-	if err != nil {
-		return err
-	}
-
-	for _, rc := range list {
-		if _, err := ss.RemoteCluster().Delete(rc.RemoteId); err != nil {
-			return err
-		}
-	}
-	return nil
-}

server/channels/store/storetest/shared_channel_store.go

@@ -393,6 +393,7 @@ func testDeleteSharedChannel(t *testing.T, rctx request.CTX, ss store.Store) {
 			ChannelId:         channel.Id,
 			CreatorId:         model.NewId(),
 			RemoteId:          model.NewId(),
+			IsInviteConfirmed: true, // to avoid adding the InclUnconfirmed filter
 		}
 		_, err := ss.SharedChannel().SaveRemote(remote)
 		require.NoError(t, err, "couldn't add remote", err)
@@ -407,10 +408,14 @@ func testDeleteSharedChannel(t *testing.T, rctx request.CTX, ss store.Store) {
 		require.Error(t, err)
 		require.Nil(t, sc)
 
-		// make sure the remotes were deleted.
+		// make sure the remotes were marked as deleted.
 		remotes, err := ss.SharedChannel().GetRemotes(0, 999999, model.SharedChannelRemoteFilterOpts{ChannelId: channel.Id})
 		require.NoError(t, err)
-		require.Len(t, remotes, 0, "expected empty remotes list")
+		require.Len(t, remotes, 0)
+
+		deletedRemotes, err := ss.SharedChannel().GetRemotes(0, 999999, model.SharedChannelRemoteFilterOpts{ChannelId: channel.Id, IncludeDeleted: true})
+		require.NoError(t, err)
+		require.Len(t, deletedRemotes, 10)
 
 		// ensure channel's Shared flag is unset
 		channelMod, err := ss.Channel().Get(channel.Id, false)
@@ -571,6 +576,17 @@ func testGetSharedChannelRemoteByIds(t *testing.T, rctx request.CTX, ss store.St
 		require.Error(t, err)
 		require.Nil(t, r)
 	})
+
+	t.Run("Get deleted shared channel remote by ids", func(t *testing.T) {
+		deleted, err := ss.SharedChannel().DeleteRemote(remoteSaved.Id)
+		require.NoError(t, err)
+		require.True(t, deleted)
+
+		r, err := ss.SharedChannel().GetRemoteByIds(remoteSaved.ChannelId, remoteSaved.RemoteId)
+		require.NoError(t, err)
+		require.Equal(t, remoteSaved.Id, r.Id)
+		require.NotZero(t, r.DeleteAt)
+	})
 }
 
 func testGetSharedChannelRemotes(t *testing.T, rctx request.CTX, ss store.Store) {
@@ -587,6 +603,7 @@ func testGetSharedChannelRemotes(t *testing.T, rctx request.CTX, ss store.Store)
 		{ChannelId: channel.Id, CreatorId: creator, RemoteId: remoteId2, IsInviteConfirmed: true},
 		{CreatorId: creator, RemoteId: remoteId, IsInviteConfirmed: true},
 		{CreatorId: creator, RemoteId: remoteId, IsInviteConfirmed: true},
+		{CreatorId: creator, RemoteId: remoteId, IsInviteConfirmed: true, DeleteAt: 123},
 		{CreatorId: creator, RemoteId: remoteId},
 	}
 
@@ -641,6 +658,25 @@ func testGetSharedChannelRemotes(t *testing.T, rctx request.CTX, ss store.Store)
 		}
 	})
 
+	t.Run("Get shared channel remotes by remote_id including deleted", func(t *testing.T) {
+		opts := model.SharedChannelRemoteFilterOpts{
+			RemoteId:       remoteId,
+			IncludeDeleted: true,
+		}
+		remotes, err := ss.SharedChannel().GetRemotes(0, 999999, opts)
+		require.NoError(t, err, "should not error", err)
+		require.Len(t, remotes, 3) // only confirmed invitations
+		deletedCount := 0
+		for _, r := range remotes {
+			require.Equal(t, remoteId, r.RemoteId)
+			require.True(t, r.IsInviteConfirmed)
+			if r.DeleteAt != 0 {
+				deletedCount++
+			}
+		}
+		require.Equal(t, 1, deletedCount)
+	})
+
 	t.Run("Get shared channel remotes by invalid remote_id", func(t *testing.T) {
 		opts := model.SharedChannelRemoteFilterOpts{
 			RemoteId: model.NewId(),
@@ -751,6 +787,20 @@ func testHasRemote(t *testing.T, rctx request.CTX, ss store.Store) {
 		require.NoError(t, err)
 		assert.False(t, has)
 	})
+
+	t.Run("deleted remote", func(t *testing.T) {
+		scr, err := ss.SharedChannel().GetRemoteByIds(channel.Id, remote1)
+		require.NoError(t, err)
+		require.NotEmpty(t, scr.Id)
+
+		deleted, err := ss.SharedChannel().DeleteRemote(scr.Id)
+		require.NoError(t, err)
+		require.True(t, deleted)
+
+		has, err := ss.SharedChannel().HasRemote(channel.Id, remote1)
+		require.NoError(t, err)
+		assert.False(t, has)
+	})
 }
 
 func testGetRemoteForUser(t *testing.T, rctx request.CTX, ss store.Store) {
@@ -888,8 +938,8 @@ func testDeleteSharedChannelRemote(t *testing.T, rctx request.CTX, ss store.Stor
 		require.True(t, deleted, "expected true from delete remote")
 
 		r, err := ss.SharedChannel().GetRemote(remoteSaved.Id)
-		require.Error(t, err)
+		require.NoError(t, err)
-		require.Nil(t, r)
+		require.NotZero(t, r.DeleteAt)
 	})
 
 	t.Run("Delete non-existent shared channel remote", func(t *testing.T) {

server/i18n/en.json

@@ -1339,7 +1339,7 @@
   },
   {
     "id": "api.command_remote.remote_table_header",
-    "translation": "| Secure connection | Display name | Connection ID | Site URL | Invite accepted | Online | Last ping  |"
+    "translation": "| Secure connection | Display name | Connection ID | Site URL | Default Team | Invite accepted | Online | Last ping | Deleted |"
   },
   {
     "id": "api.command_remote.remotes_not_found",
@@ -3758,6 +3758,10 @@
     "id": "api.upgrade_to_enterprise_status.signature.app_error",
     "translation": "Mattermost was unable to upgrade to Enterprise Edition. The digital signature of the downloaded binary file could not be verified."
   },
+  {
+    "id": "api.upload.create.upload_channel_not_shared_with_remote.app_error",
+    "translation": "Failed to upload file. Upload channel is not shared with remote."
+  },
   {
     "id": "api.upload.create.upload_too_large.app_error",
     "translation": "Unable to upload file. File is too large."

server/platform/services/sharedchannel/attachment.go

@@ -169,9 +169,13 @@ func (scs *Service) onReceiveUploadCreate(msg model.RemoteClusterMsg, rc *model.
 	}
 
 	// make sure channel is shared for the remote sender
-	if _, err := scs.server.GetStore().SharedChannel().GetRemoteByIds(us.ChannelId, rc.RemoteId); err != nil {
+	hasRemote, err := scs.server.GetStore().SharedChannel().HasRemote(us.ChannelId, rc.RemoteId)
+	if err != nil {
 		return fmt.Errorf("could not validate upload session for remote: %w", err)
 	}
+	if !hasRemote {
+		return model.NewAppError("createUpload", "api.upload.create.upload_channel_not_shared_with_remote.app_error", nil, "", http.StatusBadRequest)
+	}
 
 	// make sure file attachments are enabled
 	if scs.server.Config().FileSettings.EnableFileAttachments == nil || !*scs.server.Config().FileSettings.EnableFileAttachments {

server/platform/services/sharedchannel/channelinvite.go

@@ -6,12 +6,14 @@ package sharedchannel
 import (
 	"context"
 	"encoding/json"
+	"errors"
 	"fmt"
 	"strings"
 
 	"github.com/mattermost/mattermost/server/public/model"
 	"github.com/mattermost/mattermost/server/public/shared/mlog"
 	"github.com/mattermost/mattermost/server/public/shared/request"
+	"github.com/mattermost/mattermost/server/v8/channels/store"
 	"github.com/mattermost/mattermost/server/v8/platform/services/remotecluster"
 )
 
@@ -78,19 +80,48 @@ func (scs *Service) SendChannelInvite(channel *model.Channel, userId string, rc
 			return
 		}
 
+		existingScr, err := scs.server.GetStore().SharedChannel().GetRemoteByIds(sc.ChannelId, rc.RemoteId)
+		var errNotFound *store.ErrNotFound
+		if err != nil && !errors.As(err, &errNotFound) {
+			scs.sendEphemeralPost(channel.Id, userId, fmt.Sprintf("Error sending channel invite for %s: %s", rc.DisplayName, err))
+			return
+		}
+
+		curTime := model.GetMillis()
+		if existingScr != nil {
+			if existingScr.DeleteAt == 0 {
+				// the shared channel remote exists and is not
+				// deleted, nothing to do here
+				return
+			}
+
+			// the shared channel remote was deleted in the past, so
+			// with the new invite we restore it
+			existingScr.DeleteAt = 0
+			existingScr.UpdateAt = curTime
+			existingScr.LastPostCreateAt = curTime
+			existingScr.LastPostUpdateAt = curTime
+			if _, sErr := scs.server.GetStore().SharedChannel().UpdateRemote(existingScr); sErr != nil {
+				scs.sendEphemeralPost(channel.Id, userId, fmt.Sprintf("Error confirming channel invite for %s: %v", rc.DisplayName, sErr))
+				return
+			}
+		} else {
+			// the shared channel remote doesn't exists, so we create it
 			scr := &model.SharedChannelRemote{
 				ChannelId:         sc.ChannelId,
 				CreatorId:         userId,
 				RemoteId:          rc.RemoteId,
 				IsInviteAccepted:  true,
 				IsInviteConfirmed: true,
-			LastPostCreateAt:  model.GetMillis(),
+				LastPostCreateAt:  curTime,
-			LastPostUpdateAt:  model.GetMillis(),
+				LastPostUpdateAt:  curTime,
 			}
 			if _, err = scs.server.GetStore().SharedChannel().SaveRemote(scr); err != nil {
 				scs.sendEphemeralPost(channel.Id, userId, fmt.Sprintf("Error confirming channel invite for %s: %v", rc.DisplayName, err))
 				return
 			}
+		}
+
 		scs.NotifyChannelChanged(sc.ChannelId)
 		scs.sendEphemeralPost(channel.Id, userId, fmt.Sprintf("`%s` has been added to channel.", rc.DisplayName))
 	}
@@ -105,28 +136,7 @@ func (scs *Service) SendChannelInvite(channel *model.Channel, userId string, rc
 	ctx, cancel := context.WithTimeout(context.Background(), remotecluster.SendTimeout)
 	defer cancel()
 
-	return rcs.SendMsg(ctx, msg, rc, func(msg model.RemoteClusterMsg, rc *model.RemoteCluster, resp *remotecluster.Response, err error) {
+	return rcs.SendMsg(ctx, msg, rc, onInvite)
-		if err != nil || !resp.IsSuccess() {
-			scs.sendEphemeralPost(channel.Id, userId, fmt.Sprintf("Error sending channel invite for %s: %s", rc.DisplayName, combineErrors(err, resp.Err)))
-			return
-		}
-
-		scr := &model.SharedChannelRemote{
-			ChannelId:         sc.ChannelId,
-			CreatorId:         userId,
-			RemoteId:          rc.RemoteId,
-			IsInviteAccepted:  true,
-			IsInviteConfirmed: true,
-			LastPostCreateAt:  model.GetMillis(),
-			LastPostUpdateAt:  model.GetMillis(),
-		}
-		if _, err = scs.server.GetStore().SharedChannel().SaveRemote(scr); err != nil {
-			scs.sendEphemeralPost(channel.Id, userId, fmt.Sprintf("Error confirming channel invite for %s: %v", rc.DisplayName, err))
-			return
-		}
-		scs.NotifyChannelChanged(sc.ChannelId)
-		scs.sendEphemeralPost(channel.Id, userId, fmt.Sprintf("`%s` has been added to channel.", rc.DisplayName))
-	})
 }
 
 func combineErrors(err error, serror string) string {
@@ -162,13 +172,26 @@ func (scs *Service) onReceiveChannelInvite(msg model.RemoteClusterMsg, rc *model
 	)
 
 	// check if channel already exists
+	existingScr, err := scs.server.GetStore().SharedChannel().GetRemoteByIds(invite.ChannelId, rc.RemoteId)
+	var errNotFound *store.ErrNotFound
+	if err != nil && !errors.As(err, &errNotFound) {
+		return fmt.Errorf("cannot get deleted shared channel remote (channel_id=%s): %w", invite.ChannelId, err)
+	}
+
+	if existingScr != nil && existingScr.DeleteAt == 0 {
+		// the channel is already shared, nothing to do
+		return nil
+	}
+
 	var channel *model.Channel
 	var created bool
-	_, err := scs.server.GetStore().Channel().Get(invite.ChannelId, true)
+	if existingScr == nil {
+		var err error
+		_, err = scs.server.GetStore().Channel().Get(invite.ChannelId, true)
 		if err == nil {
-		// the channel already exists on this server; could be the remote is trying to re-share it (not allowed at this time).
+			// the channel already exists on this server and was not
-		// If the channel is already shared with the remote, it will remain so.
+			// previously shared, so we reject the invite
-		return fmt.Errorf("cannot create shared channel (channel_id=%s): %w", invite.ChannelId, model.ErrChannelAlreadyExists)
+			return fmt.Errorf("cannot create new shared channel (channel_id=%s): %w", invite.ChannelId, model.ErrChannelAlreadyExists)
 		}
 
 		// create new local channel to sync with the remote channel
@@ -201,12 +224,19 @@ func (scs *Service) onReceiveChannelInvite(msg model.RemoteClusterMsg, rc *model
 				return fmt.Errorf("cannot make channel readonly `%s`: %w", invite.ChannelId, err)
 			}
 		}
+	} else {
+		var err error
+		channel, err = scs.server.GetStore().Channel().Get(invite.ChannelId, true)
+		if err != nil {
+			return fmt.Errorf("cannot get channel (channel_id=%s) to restore a shared channel remote: %w", invite.ChannelId, err)
+		}
+	}
 
 	sharedChannel := &model.SharedChannel{
 		ChannelId:        channel.Id,
 		TeamId:           channel.TeamId,
 		Home:             false,
-		ReadOnly:         invite.ReadOnly,
+		ReadOnly:         existingScr == nil && invite.ReadOnly, // only set read only flag for new shares
 		ShareName:        channel.Name,
 		ShareDisplayName: channel.DisplayName,
 		SharePurpose:     channel.Purpose,
@@ -224,7 +254,17 @@ func (scs *Service) onReceiveChannelInvite(msg model.RemoteClusterMsg, rc *model
 		return fmt.Errorf("cannot create shared channel (channel_id=%s): %w", invite.ChannelId, err)
 	}
 
-	sharedChannelRemote := &model.SharedChannelRemote{
+	curTime := model.GetMillis()
+	if existingScr != nil {
+		existingScr.DeleteAt = 0
+		existingScr.UpdateAt = curTime
+		existingScr.LastPostCreateAt = curTime
+		existingScr.LastPostUpdateAt = curTime
+		if _, err := scs.server.GetStore().SharedChannel().UpdateRemote(existingScr); err != nil {
+			return fmt.Errorf("cannot restore deleted shared channel remote (channel_id=%s): %w", invite.ChannelId, err)
+		}
+	} else {
+		scr := &model.SharedChannelRemote{
 			Id:                model.NewId(),
 			ChannelId:         channel.Id,
 			CreatorId:         channel.CreatorId,
@@ -235,7 +275,7 @@ func (scs *Service) onReceiveChannelInvite(msg model.RemoteClusterMsg, rc *model
 			LastPostUpdateAt:  model.GetMillis(),
 		}
 
-	if _, err := scs.server.GetStore().SharedChannel().SaveRemote(sharedChannelRemote); err != nil {
+		if _, err := scs.server.GetStore().SharedChannel().SaveRemote(scr); err != nil {
 			// delete the newly created channel since we could not create a SharedChannelRemote record for it,
 			// and delete the newly created SharedChannel record as well.
 			if created {
@@ -244,6 +284,7 @@ func (scs *Service) onReceiveChannelInvite(msg model.RemoteClusterMsg, rc *model
 			scs.server.GetStore().SharedChannel().Delete(sharedChannel.ChannelId)
 			return fmt.Errorf("cannot create shared channel remote (channel_id=%s): %w", invite.ChannelId, err)
 		}
+	}
 	return nil
 }
 

server/platform/services/sharedchannel/channelinvite_test.go

@@ -62,7 +62,7 @@ func TestOnReceiveChannelInvite(t *testing.T) {
 		}
 
 		mockStore := &mocks.Store{}
-		remoteCluster := &model.RemoteCluster{Name: "test", DefaultTeamId: model.NewId()}
+		remoteCluster := &model.RemoteCluster{RemoteId: model.NewId(), Name: "test", DefaultTeamId: model.NewId()}
 		invitation := channelInviteMsg{
 			ChannelId: model.NewId(),
 			TeamId:    model.NewId(),
@@ -83,6 +83,7 @@ func TestOnReceiveChannelInvite(t *testing.T) {
 			Type:   invitation.Type,
 		}
 
+		mockSharedChannelStore.On("GetRemoteByIds", invitation.ChannelId, remoteCluster.RemoteId).Return(nil, store.NewErrNotFound("SharedChannelRemote", ""))
 		mockChannelStore.On("Get", invitation.ChannelId, true).Return(nil, &store.ErrNotFound{})
 		mockSharedChannelStore.On("Save", mock.Anything).Return(nil, nil)
 		mockSharedChannelStore.On("SaveRemote", mock.Anything).Return(nil, nil)
@@ -127,7 +128,7 @@ func TestOnReceiveChannelInvite(t *testing.T) {
 		}
 
 		mockStore := &mocks.Store{}
-		remoteCluster := &model.RemoteCluster{Name: "test2"}
+		remoteCluster := &model.RemoteCluster{RemoteId: model.NewId(), Name: "test2"}
 		invitation := channelInviteMsg{
 			ChannelId: model.NewId(),
 			TeamId:    model.NewId(),
@@ -148,11 +149,14 @@ func TestOnReceiveChannelInvite(t *testing.T) {
 		team := &model.Team{
 			Id: model.NewId(),
 		}
+		mockSharedChannelStore := mocks.SharedChannelStore{}
 
+		mockSharedChannelStore.On("GetRemoteByIds", invitation.ChannelId, remoteCluster.RemoteId).Return(nil, store.NewErrNotFound("SharedChannelRemote", ""))
 		mockChannelStore.On("Get", invitation.ChannelId, true).Return(nil, &store.ErrNotFound{})
 		mockTeamStore.On("GetAllPage", 0, 1, mock.Anything).Return([]*model.Team{team}, nil)
 		mockStore.On("Channel").Return(&mockChannelStore)
 		mockStore.On("Team").Return(&mockTeamStore)
+		mockStore.On("SharedChannel").Return(&mockSharedChannelStore)
 
 		mockServer = scs.server.(*MockServerIface)
 		mockServer.On("GetStore").Return(mockStore)
@@ -167,6 +171,96 @@ func TestOnReceiveChannelInvite(t *testing.T) {
 		assert.Equal(t, fmt.Sprintf("cannot make channel readonly `%s`: foo: bar, boom", invitation.ChannelId), err.Error())
 	})
 
+	t.Run("When invitation points to a deleted shared channel remote", func(t *testing.T) {
+		mockServer := &MockServerIface{}
+		logger := mlog.CreateConsoleTestLogger(t)
+		mockServer.On("Log").Return(logger)
+		mockApp := &MockAppIface{}
+		scs := &Service{
+			server: mockServer,
+			app:    mockApp,
+		}
+
+		mockStore := &mocks.Store{}
+		remoteCluster := &model.RemoteCluster{RemoteId: model.NewId(), Name: "test", DefaultTeamId: model.NewId()}
+		invitation := channelInviteMsg{
+			ChannelId: model.NewId(),
+			TeamId:    model.NewId(),
+			Type:      model.ChannelTypeOpen,
+		}
+		payload, err := json.Marshal(invitation)
+		require.NoError(t, err)
+
+		msg := model.RemoteClusterMsg{
+			Payload: payload,
+		}
+		mockChannelStore := mocks.ChannelStore{}
+		mockSharedChannelStore := mocks.SharedChannelStore{}
+		channel := &model.Channel{
+			Id:     invitation.ChannelId,
+			TeamId: invitation.TeamId,
+			Type:   invitation.Type,
+		}
+		sharedChannelRemote := &model.SharedChannelRemote{
+			ChannelId: invitation.ChannelId,
+			RemoteId:  remoteCluster.RemoteId,
+			DeleteAt:  1234,
+		}
+
+		mockSharedChannelStore.On("GetRemoteByIds", invitation.ChannelId, mock.Anything).Return(sharedChannelRemote, nil)
+		mockChannelStore.On("Get", invitation.ChannelId, true).Return(channel, nil)
+		mockSharedChannelStore.On("Save", mock.Anything).Return(nil, nil)
+		mockSharedChannelStore.On("UpdateRemote", mock.Anything).Return(nil, nil)
+		mockStore.On("Channel").Return(&mockChannelStore)
+		mockStore.On("SharedChannel").Return(&mockSharedChannelStore)
+
+		mockServer.On("GetStore").Return(mockStore)
+		defer mockApp.AssertExpectations(t)
+
+		err = scs.onReceiveChannelInvite(msg, remoteCluster, nil)
+		require.NoError(t, err)
+	})
+
+	t.Run("When invitation points to an existing shared channel remote", func(t *testing.T) {
+		mockServer := &MockServerIface{}
+		logger := mlog.CreateConsoleTestLogger(t)
+		mockServer.On("Log").Return(logger)
+		mockApp := &MockAppIface{}
+		scs := &Service{
+			server: mockServer,
+			app:    mockApp,
+		}
+
+		mockStore := &mocks.Store{}
+		remoteCluster := &model.RemoteCluster{RemoteId: model.NewId(), Name: "test", DefaultTeamId: model.NewId()}
+		invitation := channelInviteMsg{
+			ChannelId: model.NewId(),
+			TeamId:    model.NewId(),
+			Type:      model.ChannelTypeOpen,
+		}
+		payload, err := json.Marshal(invitation)
+		require.NoError(t, err)
+
+		msg := model.RemoteClusterMsg{
+			Payload: payload,
+		}
+		mockSharedChannelStore := mocks.SharedChannelStore{}
+		sharedChannelRemote := &model.SharedChannelRemote{
+			ChannelId: invitation.ChannelId,
+			RemoteId:  remoteCluster.RemoteId,
+			DeleteAt:  0,
+		}
+
+		mockServer.On("GetStore").Return(mockStore)
+		mockSharedChannelStore.On("GetRemoteByIds", invitation.ChannelId, remoteCluster.RemoteId).Return(sharedChannelRemote, nil)
+		mockStore.On("SharedChannel").Return(&mockSharedChannelStore)
+
+		defer mockApp.AssertExpectations(t)
+
+		err = scs.onReceiveChannelInvite(msg, remoteCluster, nil)
+		require.NoError(t, err)
+	})
+
 	t.Run("DM channels", func(t *testing.T) {
 		var testRemoteID = model.NewId()
 		testCases := []struct {
@@ -196,7 +290,7 @@ func TestOnReceiveChannelInvite(t *testing.T) {
 				}
 
 				mockStore := &mocks.Store{}
-				remoteCluster := &model.RemoteCluster{Name: "test3", CreatorId: model.NewId(), RemoteId: testRemoteID}
+				remoteCluster := &model.RemoteCluster{RemoteId: testRemoteID, Name: "test3", CreatorId: model.NewId()}
 				invitation := channelInviteMsg{
 					ChannelId:            model.NewId(),
 					TeamId:               model.NewId(),
@@ -225,6 +319,7 @@ func TestOnReceiveChannelInvite(t *testing.T) {
 				mockChannelStore.On("Get", invitation.ChannelId, true).Return(nil, errors.New("boom"))
 				mockChannelStore.On("GetByName", "", mockTypeString, true).Return(nil, &store.ErrNotFound{})
 
+				mockSharedChannelStore.On("GetRemoteByIds", invitation.ChannelId, remoteCluster.RemoteId).Return(nil, store.NewErrNotFound("SharedChannelRemote", ""))
 				mockSharedChannelStore.On("Save", mock.Anything).Return(nil, nil)
 				mockSharedChannelStore.On("SaveRemote", mock.Anything).Return(nil, nil)
 				mockStore.On("Channel").Return(&mockChannelStore)

server/platform/services/sharedchannel/service_api.go

@@ -170,7 +170,7 @@ func (scs *Service) InviteRemoteToChannel(channelID, remoteID, userID string, sh
 
 func (scs *Service) UninviteRemoteFromChannel(channelID, remoteID string) error {
 	scr, err := scs.server.GetStore().SharedChannel().GetRemoteByIds(channelID, remoteID)
-	if err != nil || scr.ChannelId != channelID {
+	if err != nil || scr.ChannelId != channelID || scr.DeleteAt != 0 {
 		return model.NewAppError("UninviteRemoteFromChannel", "api.command_share.channel_remote_id_not_exists",
 			map[string]any{"RemoteId": remoteID}, "", http.StatusInternalServerError)
 	}

server/platform/services/sharedchannel/sync_send.go

@@ -343,6 +343,9 @@ func (scs *Service) processTask(task syncTask) error {
 		if err != nil {
 			return err
 		}
+		if rc.DeleteAt != 0 {
+			return fmt.Errorf("Processing task for a deleted remote cluster '%s'", task.remoteID)
+		}
 		if !rc.IsOnline() {
 			return fmt.Errorf("Failed updating shared channel '%s' for offline remote cluster '%s'", task.channelID, rc.DisplayName)
 		}

server/platform/services/sharedchannel/sync_send_remote.go

@@ -119,6 +119,9 @@ func (scs *Service) syncForRemote(task syncTask, rc *model.RemoteCluster) error
 			mlog.String("remote", rc.DisplayName),
 			mlog.String("channel_id", task.channelID),
 		)
+	} else if err == nil && scr.DeleteAt != 0 {
+		// if SharedChannelRemote is deleted, regardless of the autoinvite flag, do nothing
+		return nil
 	} else if err != nil {
 		return err
 	}

server/public/model/client4.go

@@ -8781,6 +8781,9 @@ func (c *Client4) GetRemoteClusters(ctx context.Context, page, perPage int, filt
 	if filter.ExcludePlugins {
 		v.Set("exclude_plugins", "true")
 	}
+	if filter.IncludeDeleted {
+		v.Set("include_deleted", "true")
+	}
 	url := c.remoteClusterRoute()
 	if len(v) > 0 {
 		url += "?" + v.Encode()
@@ -8894,7 +8897,7 @@ func (c *Client4) DeleteRemoteCluster(ctx context.Context, remoteClusterId strin
 	return BuildResponse(r), nil
 }
 
-func (c *Client4) GetSharedChannelRemotesByRemoteCluster(ctx context.Context, remoteId string, excludeHome, excludeRemote bool, page, perPage int) ([]*SharedChannelRemote, *Response, error) {
+func (c *Client4) GetSharedChannelRemotesByRemoteCluster(ctx context.Context, remoteId string, excludeHome, excludeRemote, includeDeleted bool, page, perPage int) ([]*SharedChannelRemote, *Response, error) {
 	v := url.Values{}
 	if excludeHome {
 		v.Set("exclude_home", "true")
@@ -8902,6 +8905,9 @@ func (c *Client4) GetSharedChannelRemotesByRemoteCluster(ctx context.Context, re
 	if excludeRemote {
 		v.Set("exclude_remote", "true")
 	}
+	if includeDeleted {
+		v.Set("include_deleted", "true")
+	}
 	if page != 0 {
 		v.Set("page", fmt.Sprintf("%d", page))
 	}

server/public/model/remote_cluster.go

@@ -57,6 +57,7 @@ type RemoteCluster struct {
 	SiteURL       string  `json:"site_url"`
 	DefaultTeamId string  `json:"default_team_id"`
 	CreateAt      int64   `json:"create_at"`
+	DeleteAt      int64   `json:"delete_at"`
 	LastPingAt    int64   `json:"last_ping_at"`
 	Token         string  `json:"token"`
 	RemoteToken   string  `json:"remote_token"`
@@ -75,6 +76,7 @@ func (rc *RemoteCluster) Auditable() map[string]interface{} {
 		"site_url":        rc.SiteURL,
 		"default_team_id": rc.DefaultTeamId,
 		"create_at":       rc.CreateAt,
+		"delete_at":       rc.DeleteAt,
 		"last_ping_at":    rc.LastPingAt,
 		"creator_id":      rc.CreatorId,
 		"plugin_id":       rc.PluginID,
@@ -271,6 +273,7 @@ func (rc *RemoteCluster) ToRemoteClusterInfo() RemoteClusterInfo {
 		Name:        rc.Name,
 		DisplayName: rc.DisplayName,
 		CreateAt:    rc.CreateAt,
+		DeleteAt:    rc.DeleteAt,
 		LastPingAt:  rc.LastPingAt,
 	}
 }
@@ -284,6 +287,7 @@ type RemoteClusterInfo struct {
 	Name        string `json:"name"`
 	DisplayName string `json:"display_name"`
 	CreateAt    int64  `json:"create_at"`
+	DeleteAt    int64  `json:"delete_at"`
 	LastPingAt  int64  `json:"last_ping_at"`
 }
 
@@ -457,4 +461,5 @@ type RemoteClusterQueryFilter struct {
 	OnlyPlugins    bool
 	ExcludePlugins bool
 	RequireOptions Bitmask
+	IncludeDeleted bool
 }

server/public/model/shared_channel.go

@@ -110,6 +110,7 @@ type SharedChannelRemote struct {
 	CreatorId         string `json:"creator_id"`
 	CreateAt          int64  `json:"create_at"`
 	UpdateAt          int64  `json:"update_at"`
+	DeleteAt          int64  `json:"delete_at"`
 	IsInviteAccepted  bool   `json:"is_invite_accepted"`
 	IsInviteConfirmed bool   `json:"is_invite_confirmed"`
 	RemoteId          string `json:"remote_id"`
@@ -265,6 +266,7 @@ type SharedChannelRemoteFilterOpts struct {
 	InclUnconfirmed bool
 	ExcludeHome     bool
 	ExcludeRemote   bool
+	IncludeDeleted  bool
 }
 
 // SyncMsg represents a change in content (post add/edit/delete, reaction add/remove, users).