[MM-27622] Publish messages as SystemBot when a user is required (#17598)

Automatic Merge

api4/channel_local.go

@@ -6,6 +6,7 @@ package api4
 import (
 	"net/http"
 
+	"github.com/mattermost/mattermost-server/v5/app"
 	"github.com/mattermost/mattermost-server/v5/audit"
 	"github.com/mattermost/mattermost-server/v5/model"
 )
@@ -18,6 +19,8 @@ func (api *API) InitChannelLocal() {
 	api.BaseRoutes.Channel.Handle("", api.ApiLocal(localDeleteChannel)).Methods("DELETE")
 	api.BaseRoutes.Channel.Handle("/patch", api.ApiLocal(localPatchChannel)).Methods("PUT")
 	api.BaseRoutes.Channel.Handle("/move", api.ApiLocal(localMoveChannel)).Methods("POST")
+	api.BaseRoutes.Channel.Handle("/privacy", api.ApiLocal(localUpdateChannelPrivacy)).Methods("PUT")
+	api.BaseRoutes.Channel.Handle("/restore", api.ApiLocal(localRestoreChannel)).Methods("POST")
 
 	api.BaseRoutes.ChannelMember.Handle("", api.ApiLocal(localRemoveChannelMember)).Methods("DELETE")
 	api.BaseRoutes.ChannelMember.Handle("", api.ApiLocal(getChannelMember)).Methods("GET")
@@ -57,6 +60,76 @@ func localCreateChannel(c *Context, w http.ResponseWriter, r *http.Request) {
 	w.Write([]byte(sc.ToJson()))
 }
 
+func localUpdateChannelPrivacy(c *Context, w http.ResponseWriter, r *http.Request) {
+	c.RequireChannelId()
+	if c.Err != nil {
+		return
+	}
+
+	props := model.StringInterfaceFromJson(r.Body)
+	privacy, ok := props["privacy"].(string)
+	if !ok || (privacy != model.CHANNEL_OPEN && privacy != model.CHANNEL_PRIVATE) {
+		c.SetInvalidParam("privacy")
+		return
+	}
+
+	channel, err := c.App.GetChannel(c.Params.ChannelId)
+	if err != nil {
+		c.Err = err
+		return
+	}
+
+	auditRec := c.MakeAuditRecord("localUpdateChannelPrivacy", audit.Fail)
+	defer c.LogAuditRec(auditRec)
+	auditRec.AddMeta("channel", channel)
+	auditRec.AddMeta("new_type", privacy)
+
+	if channel.Name == model.DEFAULT_CHANNEL && privacy == model.CHANNEL_PRIVATE {
+		c.Err = model.NewAppError("updateChannelPrivacy", "api.channel.update_channel_privacy.default_channel_error", nil, "", http.StatusBadRequest)
+		return
+	}
+	channel.Type = privacy
+
+	updatedChannel, err := c.App.UpdateChannelPrivacy(c.AppContext, channel, nil)
+	if err != nil {
+		c.Err = err
+		return
+	}
+
+	auditRec.Success()
+	c.LogAudit("name=" + updatedChannel.Name)
+
+	w.Write([]byte(updatedChannel.ToJson()))
+}
+
+func localRestoreChannel(c *Context, w http.ResponseWriter, r *http.Request) {
+	c.RequireChannelId()
+	if c.Err != nil {
+		return
+	}
+
+	channel, err := c.App.GetChannel(c.Params.ChannelId)
+	if err != nil {
+		c.Err = err
+		return
+	}
+
+	auditRec := c.MakeAuditRecord("localRestoreChannel", audit.Fail)
+	defer c.LogAuditRec(auditRec)
+	auditRec.AddMeta("channel", channel)
+
+	channel, err = c.App.RestoreChannel(c.AppContext, channel, "")
+	if err != nil {
+		c.Err = err
+		return
+	}
+
+	auditRec.Success()
+	c.LogAudit("name=" + channel.Name)
+
+	w.Write([]byte(channel.ToJson()))
+}
+
 func localAddChannelMember(c *Context, w http.ResponseWriter, r *http.Request) {
 	c.RequireChannelId()
 	if c.Err != nil {
@@ -70,13 +143,30 @@ func localAddChannelMember(c *Context, w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
-	user, err := c.App.GetUser(userId)
+	member := &model.ChannelMember{
+		ChannelId: c.Params.ChannelId,
+		UserId:    userId,
+	}
+
+	postRootId, ok := props["post_root_id"].(string)
+	if ok && postRootId != "" && !model.IsValidId(postRootId) {
+		c.SetInvalidParam("post_root_id")
+		return
+	}
+
+	if ok && len(postRootId) == 26 {
+		rootPost, err := c.App.GetSinglePost(postRootId)
 		if err != nil {
 			c.Err = err
 			return
 		}
+		if rootPost.ChannelId != member.ChannelId {
+			c.SetInvalidParam("post_root_id")
+			return
+		}
+	}
 
-	channel, err := c.App.GetChannel(c.Params.ChannelId)
+	channel, err := c.App.GetChannel(member.ChannelId)
 	if err != nil {
 		c.Err = err
 		return
@@ -87,27 +177,29 @@ func localAddChannelMember(c *Context, w http.ResponseWriter, r *http.Request) {
 	auditRec.AddMeta("channel", channel)
 
 	if channel.Type == model.CHANNEL_DIRECT || channel.Type == model.CHANNEL_GROUP {
-		c.Err = model.NewAppError("addUserToChannel", "api.channel.add_user_to_channel.type.app_error", nil, "", http.StatusBadRequest)
+		c.Err = model.NewAppError("localAddChannelMember", "api.channel.add_user_to_channel.type.app_error", nil, "", http.StatusBadRequest)
 		return
 	}
 
 	if channel.IsGroupConstrained() {
-		nonMembers, err := c.App.FilterNonGroupChannelMembers([]string{user.Id}, channel)
+		nonMembers, err := c.App.FilterNonGroupChannelMembers([]string{member.UserId}, channel)
 		if err != nil {
 			if v, ok := err.(*model.AppError); ok {
 				c.Err = v
 			} else {
-				c.Err = model.NewAppError("addChannelMember", "api.channel.add_members.error", nil, err.Error(), http.StatusBadRequest)
+				c.Err = model.NewAppError("localAddChannelMember", "api.channel.add_members.error", nil, err.Error(), http.StatusBadRequest)
 			}
 			return
 		}
 		if len(nonMembers) > 0 {
-			c.Err = model.NewAppError("addChannelMember", "api.channel.add_members.user_denied", map[string]interface{}{"UserIDs": nonMembers}, "", http.StatusBadRequest)
+			c.Err = model.NewAppError("localAddChannelMember", "api.channel.add_members.user_denied", map[string]interface{}{"UserIDs": nonMembers}, "", http.StatusBadRequest)
 			return
 		}
 	}
 
-	cm, err := c.App.AddUserToChannel(user, channel, false)
+	cm, err := c.App.AddChannelMember(c.AppContext, member.UserId, channel, app.ChannelMemberOpts{
+		PostRootID: postRootId,
+	})
 	if err != nil {
 		c.Err = err
 		return

api4/channel_test.go

@@ -1844,7 +1844,8 @@ func TestConvertChannelToPrivate(t *testing.T) {
 func TestUpdateChannelPrivacy(t *testing.T) {
 	th := Setup(t).InitBasic()
 	defer th.TearDown()
-	Client := th.Client
+
+	defaultChannel, _ := th.App.GetChannelByName(model.DEFAULT_CHANNEL, th.BasicTeam.Id, false)
 
 	type testTable []struct {
 		name            string
@@ -1852,7 +1853,7 @@ func TestUpdateChannelPrivacy(t *testing.T) {
 		expectedPrivacy string
 	}
 
-	defaultChannel, _ := th.App.GetChannelByName(model.DEFAULT_CHANNEL, th.BasicTeam.Id, false)
+	t.Run("Should get a forbidden response if not logged in", func(t *testing.T) {
 		privateChannel := th.CreatePrivateChannel()
 		publicChannel := th.CreatePublicChannel()
 
@@ -1864,21 +1865,24 @@ func TestUpdateChannelPrivacy(t *testing.T) {
 
 		for _, tc := range tt {
 			t.Run(tc.name, func(t *testing.T) {
-			_, resp := Client.UpdateChannelPrivacy(tc.channel.Id, tc.expectedPrivacy)
+				_, resp := th.Client.UpdateChannelPrivacy(tc.channel.Id, tc.expectedPrivacy)
 				CheckForbiddenStatus(t, resp)
 			})
 		}
+	})
 
-	th.LoginTeamAdmin()
+	th.TestForSystemAdminAndLocal(t, func(t *testing.T, client *model.Client4) {
+		privateChannel := th.CreatePrivateChannel()
+		publicChannel := th.CreatePublicChannel()
 
-	tt = testTable{
+		tt := testTable{
 			{"Converting default channel to private should fail", defaultChannel, model.CHANNEL_PRIVATE},
 			{"Updating privacy to an invalid setting should fail", publicChannel, "invalid"},
 		}
 
 		for _, tc := range tt {
 			t.Run(tc.name, func(t *testing.T) {
-			_, resp := Client.UpdateChannelPrivacy(tc.channel.Id, tc.expectedPrivacy)
+				_, resp := client.UpdateChannelPrivacy(tc.channel.Id, tc.expectedPrivacy)
 				CheckBadRequestStatus(t, resp)
 			})
 		}
@@ -1893,7 +1897,7 @@ func TestUpdateChannelPrivacy(t *testing.T) {
 
 		for _, tc := range tt {
 			t.Run(tc.name, func(t *testing.T) {
-			updatedChannel, resp := Client.UpdateChannelPrivacy(tc.channel.Id, tc.expectedPrivacy)
+				updatedChannel, resp := client.UpdateChannelPrivacy(tc.channel.Id, tc.expectedPrivacy)
 				CheckNoError(t, resp)
 				assert.Equal(t, tc.expectedPrivacy, updatedChannel.Type)
 				updatedChannel, err := th.App.GetChannel(tc.channel.Id)
@@ -1901,51 +1905,60 @@ func TestUpdateChannelPrivacy(t *testing.T) {
 				assert.Equal(t, tc.expectedPrivacy, updatedChannel.Type)
 			})
 		}
+	})
 
 	t.Run("Enforces convert channel permissions", func(t *testing.T) {
+		privateChannel := th.CreatePrivateChannel()
+		publicChannel := th.CreatePublicChannel()
+
+		th.LoginTeamAdmin()
+
 		th.RemovePermissionFromRole(model.PERMISSION_CONVERT_PUBLIC_CHANNEL_TO_PRIVATE.Id, model.TEAM_ADMIN_ROLE_ID)
 		th.RemovePermissionFromRole(model.PERMISSION_CONVERT_PRIVATE_CHANNEL_TO_PUBLIC.Id, model.TEAM_ADMIN_ROLE_ID)
 
-		_, resp := Client.UpdateChannelPrivacy(publicChannel.Id, model.CHANNEL_PRIVATE)
+		_, resp := th.Client.UpdateChannelPrivacy(publicChannel.Id, model.CHANNEL_PRIVATE)
 		CheckForbiddenStatus(t, resp)
-		_, resp = Client.UpdateChannelPrivacy(privateChannel.Id, model.CHANNEL_OPEN)
+		_, resp = th.Client.UpdateChannelPrivacy(privateChannel.Id, model.CHANNEL_OPEN)
 		CheckForbiddenStatus(t, resp)
 
 		th.AddPermissionToRole(model.PERMISSION_CONVERT_PUBLIC_CHANNEL_TO_PRIVATE.Id, model.TEAM_ADMIN_ROLE_ID)
 		th.AddPermissionToRole(model.PERMISSION_CONVERT_PRIVATE_CHANNEL_TO_PUBLIC.Id, model.TEAM_ADMIN_ROLE_ID)
 
-		_, resp = Client.UpdateChannelPrivacy(privateChannel.Id, model.CHANNEL_OPEN)
+		_, resp = th.Client.UpdateChannelPrivacy(privateChannel.Id, model.CHANNEL_OPEN)
 		CheckNoError(t, resp)
-		_, resp = Client.UpdateChannelPrivacy(publicChannel.Id, model.CHANNEL_PRIVATE)
+		_, resp = th.Client.UpdateChannelPrivacy(publicChannel.Id, model.CHANNEL_PRIVATE)
 		CheckNoError(t, resp)
 	})
-
 }
 
 func TestRestoreChannel(t *testing.T) {
 	th := Setup(t).InitBasic()
 	defer th.TearDown()
-	Client := th.Client
 
 	publicChannel1 := th.CreatePublicChannel()
-	Client.DeleteChannel(publicChannel1.Id)
+	th.Client.DeleteChannel(publicChannel1.Id)
 
 	privateChannel1 := th.CreatePrivateChannel()
-	Client.DeleteChannel(privateChannel1.Id)
+	th.Client.DeleteChannel(privateChannel1.Id)
 
-	_, resp := Client.RestoreChannel(publicChannel1.Id)
+	_, resp := th.Client.RestoreChannel(publicChannel1.Id)
 	CheckForbiddenStatus(t, resp)
 
-	_, resp = Client.RestoreChannel(privateChannel1.Id)
+	_, resp = th.Client.RestoreChannel(privateChannel1.Id)
 	CheckForbiddenStatus(t, resp)
 
-	th.LoginTeamAdmin()
+	th.TestForSystemAdminAndLocal(t, func(t *testing.T, client *model.Client4) {
+		defer func() {
+			client.DeleteChannel(publicChannel1.Id)
+			client.DeleteChannel(privateChannel1.Id)
+		}()
 
-	_, resp = Client.RestoreChannel(publicChannel1.Id)
+		_, resp = client.RestoreChannel(publicChannel1.Id)
 		CheckOKStatus(t, resp)
 
-	_, resp = Client.RestoreChannel(privateChannel1.Id)
+		_, resp = client.RestoreChannel(privateChannel1.Id)
 		CheckOKStatus(t, resp)
+	})
 }
 
 func TestGetChannelByName(t *testing.T) {
@@ -2052,7 +2065,6 @@ func TestGetChannelMembers(t *testing.T) {
 	th := Setup(t).InitBasic()
 	defer th.TearDown()
 	th.TestForAllClients(t, func(t *testing.T, client *model.Client4) {
-
 		members, resp := client.GetChannelMembers(th.BasicChannel.Id, 0, 60, "")
 		CheckNoError(t, resp)
 		require.Len(t, *members, 3, "should only be 3 users in channel")

app/app.go

@@ -237,6 +237,17 @@ func (a *App) getWarnMetricStatusAndDisplayTextsForId(warnMetricId string, T i18
 
 //nolint:golint,unused,deadcode
 func (a *App) notifyAdminsOfWarnMetricStatus(c *request.Context, warnMetricId string, isE0Edition bool) *model.AppError {
+	// get warn metrics bot
+	warnMetricsBot, err := a.GetWarnMetricsBot()
+	if err != nil {
+		return err
+	}
+
+	warnMetric, ok := model.WarnMetricsTable[warnMetricId]
+	if !ok {
+		return model.NewAppError("NotifyAdminsOfWarnMetricStatus", "app.system.warn_metric.notification.invalid_metric.app_error", nil, "", http.StatusInternalServerError)
+	}
+
 	perPage := 25
 	userOptions := &model.UserGetOptions{
 		Page:     0,
@@ -264,30 +275,12 @@ func (a *App) notifyAdminsOfWarnMetricStatus(c *request.Context, warnMetricId st
 		}
 	}
 
-	T := i18n.GetUserTranslations(sysAdmins[0].Locale)
-	warnMetricsBot := &model.Bot{
-		Username:    model.BOT_WARN_METRIC_BOT_USERNAME,
-		DisplayName: T("app.system.warn_metric.bot_displayname"),
-		Description: "",
-		OwnerId:     sysAdmins[0].Id,
-	}
-
-	bot, err := a.getOrCreateWarnMetricsBot(warnMetricsBot)
-	if err != nil {
-		return err
-	}
-
-	warnMetric, ok := model.WarnMetricsTable[warnMetricId]
-	if !ok {
-		return model.NewAppError("NotifyAdminsOfWarnMetricStatus", "app.system.warn_metric.notification.invalid_metric.app_error", nil, "", http.StatusInternalServerError)
-	}
-
 	for _, sysAdmin := range sysAdmins {
 		T := i18n.GetUserTranslations(sysAdmin.Locale)
-		bot.DisplayName = T("app.system.warn_metric.bot_displayname")
+		warnMetricsBot.DisplayName = T("app.system.warn_metric.bot_displayname")
-		bot.Description = T("app.system.warn_metric.bot_description")
+		warnMetricsBot.Description = T("app.system.warn_metric.bot_description")
 
-		channel, appErr := a.GetOrCreateDirectChannel(c, bot.UserId, sysAdmin.Id)
+		channel, appErr := a.GetOrCreateDirectChannel(c, warnMetricsBot.UserId, sysAdmin.Id)
 		if appErr != nil {
 			return appErr
 		}
@@ -298,7 +291,7 @@ func (a *App) notifyAdminsOfWarnMetricStatus(c *request.Context, warnMetricId st
 		}
 
 		botPost := &model.Post{
-			UserId:    bot.UserId,
+			UserId:    warnMetricsBot.UserId,
 			ChannelId: channel.Id,
 			Type:      model.POST_SYSTEM_WARN_METRIC_STATUS,
 			Message:   "",
@@ -334,7 +327,7 @@ func (a *App) notifyAdminsOfWarnMetricStatus(c *request.Context, warnMetricId st
 				},
 				Integration: &model.PostActionIntegration{
 					Context: model.StringInterface{
-						"bot_user_id": bot.UserId,
+						"bot_user_id": warnMetricsBot.UserId,
 						"force_ack":   false,
 					},
 					URL: postActionUrl,

app/app_iface.go

@@ -382,6 +382,8 @@ type AppIface interface {
 	VerifyPlugin(plugin, signature io.ReadSeeker) *model.AppError
 	//GetUserStatusesByIds used by apiV4
 	GetUserStatusesByIds(userIDs []string) ([]*model.Status, *model.AppError)
+	//nolint:golint,unused,deadcode
+	GetWarnMetricsBot() (*model.Bot, *model.AppError)
 	AccountMigration() einterfaces.AccountMigrationInterface
 	ActivateMfa(userID, token string) *model.AppError
 	AddChannelsToRetentionPolicy(policyID string, channelIDs []string) *model.AppError
@@ -736,6 +738,7 @@ type AppIface interface {
 	GetStatusFromCache(userID string) *model.Status
 	GetStatusesByIds(userIDs []string) (map[string]interface{}, *model.AppError)
 	GetSubscriptionStats() (*model.SubscriptionStats, *model.AppError)
+	GetSystemBot() (*model.Bot, *model.AppError)
 	GetTeam(teamID string) (*model.Team, *model.AppError)
 	GetTeamByInviteId(inviteId string) (*model.Team, *model.AppError)
 	GetTeamByName(name string) (*model.Team, *model.AppError)

app/bot.go

@@ -91,7 +91,65 @@ func (a *App) CreateBot(c *request.Context, bot *model.Bot) (*model.Bot, *model.
 }
 
 //nolint:golint,unused,deadcode
-func (a *App) getOrCreateWarnMetricsBot(botDef *model.Bot) (*model.Bot, *model.AppError) {
+func (a *App) GetWarnMetricsBot() (*model.Bot, *model.AppError) {
+	perPage := 1
+	userOptions := &model.UserGetOptions{
+		Page:     0,
+		PerPage:  perPage,
+		Role:     model.SYSTEM_ADMIN_ROLE_ID,
+		Inactive: false,
+	}
+
+	sysAdminList, err := a.GetUsers(userOptions)
+	if err != nil {
+		return nil, err
+	}
+
+	if len(sysAdminList) == 0 {
+		return nil, model.NewAppError("GetWarnMetricsBot", "app.bot.get_warn_metrics_bot.empty_admin_list.app_error", nil, "", http.StatusInternalServerError)
+	}
+
+	T := i18n.GetUserTranslations(sysAdminList[0].Locale)
+	warnMetricsBot := &model.Bot{
+		Username:    model.BOT_WARN_METRIC_BOT_USERNAME,
+		DisplayName: T("app.system.warn_metric.bot_displayname"),
+		Description: "",
+		OwnerId:     sysAdminList[0].Id,
+	}
+
+	return a.getOrCreateBot(warnMetricsBot)
+}
+
+func (a *App) GetSystemBot() (*model.Bot, *model.AppError) {
+	perPage := 1
+	userOptions := &model.UserGetOptions{
+		Page:     0,
+		PerPage:  perPage,
+		Role:     model.SYSTEM_ADMIN_ROLE_ID,
+		Inactive: false,
+	}
+
+	sysAdminList, err := a.GetUsers(userOptions)
+	if err != nil {
+		return nil, err
+	}
+
+	if len(sysAdminList) == 0 {
+		return nil, model.NewAppError("GetSystemBot", "app.bot.get_system_bot.empty_admin_list.app_error", nil, "", http.StatusInternalServerError)
+	}
+
+	T := i18n.GetUserTranslations(sysAdminList[0].Locale)
+	systemBot := &model.Bot{
+		Username:    model.BOT_SYSTEM_BOT_USERNAME,
+		DisplayName: T("app.system.system_bot.bot_displayname"),
+		Description: "",
+		OwnerId:     sysAdminList[0].Id,
+	}
+
+	return a.getOrCreateBot(systemBot)
+}
+
+func (a *App) getOrCreateBot(botDef *model.Bot) (*model.Bot, *model.AppError) {
 	botUser, appErr := a.GetUserByUsername(botDef.Username)
 	if appErr != nil {
 		if appErr.StatusCode != http.StatusNotFound {
@@ -116,9 +174,9 @@ func (a *App) getOrCreateWarnMetricsBot(botDef *model.Bot) (*model.Bot, *model.A
 				default:
 					code = "app.user.save.existing.app_error"
 				}
-				return nil, model.NewAppError("getOrCreateWarnMetricsBot", code, nil, invErr.Error(), http.StatusBadRequest)
+				return nil, model.NewAppError("getOrCreateBot", code, nil, invErr.Error(), http.StatusBadRequest)
 			default:
-				return nil, model.NewAppError("getOrCreateWarnMetricsBot", "app.user.save.app_error", nil, nErr.Error(), http.StatusInternalServerError)
+				return nil, model.NewAppError("getOrCreateBot", "app.user.save.app_error", nil, nErr.Error(), http.StatusInternalServerError)
 			}
 		}
 		botDef.UserId = user.Id
@@ -132,14 +190,14 @@ func (a *App) getOrCreateWarnMetricsBot(botDef *model.Bot) (*model.Bot, *model.A
 			case errors.As(nErr, &nAppErr): // in case we haven't converted to plain error.
 				return nil, nAppErr
 			default: // last fallback in case it doesn't map to an existing app error.
-				return nil, model.NewAppError("getOrCreateWarnMetricsBot", "app.bot.createbot.internal_error", nil, nErr.Error(), http.StatusInternalServerError)
+				return nil, model.NewAppError("getOrCreateBot", "app.bot.createbot.internal_error", nil, nErr.Error(), http.StatusInternalServerError)
 			}
 		}
 		return savedBot, nil
 	}
 
 	if botUser == nil {
-		return nil, model.NewAppError("getOrCreateWarnMetricsBot", "app.bot.createbot.internal_error", nil, "", http.StatusInternalServerError)
+		return nil, model.NewAppError("getOrCreateBot", "app.bot.createbot.internal_error", nil, "", http.StatusInternalServerError)
 	}
 
 	//return the bot for this user

app/bot_test.go

@@ -915,6 +915,44 @@ func TestDeleteBotIconImage(t *testing.T) {
 	})
 }
 
+func TestGetSystemBot(t *testing.T) {
+	t.Run("An error should be returned if there are no sysadmins in the instance", func(t *testing.T) {
+		th := Setup(t).InitBasic()
+		defer th.TearDown()
+
+		require.Nil(t, th.App.PermanentDeleteAllUsers(th.Context))
+
+		_, err := th.App.GetSystemBot()
+		require.NotNil(t, err)
+		require.Equal(t, "app.bot.get_system_bot.empty_admin_list.app_error", err.Id)
+	})
+
+	th := Setup(t).InitBasic()
+	defer th.TearDown()
+
+	t.Run("The bot should be created the first time it's retrieved", func(t *testing.T) {
+		// assert no bot with username exists
+		_, err := th.App.GetUserByUsername(model.BOT_SYSTEM_BOT_USERNAME)
+		require.NotNil(t, err)
+
+		bot, err := th.App.GetSystemBot()
+		require.Nil(t, err)
+		require.Equal(t, bot.Username, model.BOT_SYSTEM_BOT_USERNAME)
+	})
+
+	t.Run("The bot should be correctly retrieved if it exists already", func(t *testing.T) {
+		// assert that the bot is now present
+		botUser, err := th.App.GetUserByUsername(model.BOT_SYSTEM_BOT_USERNAME)
+		require.Nil(t, err)
+		require.True(t, botUser.IsBot)
+
+		bot, err := th.App.GetSystemBot()
+		require.Nil(t, err)
+		require.Equal(t, bot.Username, model.BOT_SYSTEM_BOT_USERNAME)
+		require.Equal(t, bot.UserId, botUser.Id)
+	})
+}
+
 func sToP(s string) *string {
 	return &s
 }

app/channel.go

@@ -710,6 +710,21 @@ func (a *App) UpdateChannelPrivacy(c *request.Context, oldChannel *model.Channel
 }
 
 func (a *App) postChannelPrivacyMessage(c *request.Context, user *model.User, channel *model.Channel) *model.AppError {
+	var authorId string
+	var authorUsername string
+	if user != nil {
+		authorId = user.Id
+		authorUsername = user.Username
+	} else {
+		systemBot, err := a.GetSystemBot()
+		if err != nil {
+			return model.NewAppError("postChannelPrivacyMessage", "api.channel.post_channel_privacy_message.error", nil, err.Error(), http.StatusInternalServerError)
+		}
+
+		authorId = systemBot.UserId
+		authorUsername = systemBot.Username
+	}
+
 	message := (map[string]string{
 		model.CHANNEL_OPEN:    i18n.T("api.channel.change_channel_privacy.private_to_public"),
 		model.CHANNEL_PRIVATE: i18n.T("api.channel.change_channel_privacy.public_to_private"),
@@ -718,9 +733,9 @@ func (a *App) postChannelPrivacyMessage(c *request.Context, user *model.User, ch
 		ChannelId: channel.Id,
 		Message:   message,
 		Type:      model.POST_CHANGE_CHANNEL_PRIVACY,
-		UserId:    user.Id,
+		UserId:    authorId,
 		Props: model.StringInterface{
-			"username": user.Username,
+			"username": authorUsername,
 		},
 	}
 
@@ -746,7 +761,10 @@ func (a *App) RestoreChannel(c *request.Context, channel *model.Channel, userID
 	message.Add("channel_id", channel.Id)
 	a.Publish(message)
 
-	user, nErr := a.Srv().Store.User().Get(context.Background(), userID)
+	var user *model.User
+	if userID != "" {
+		var nErr error
+		user, nErr = a.Srv().Store.User().Get(context.Background(), userID)
 		if nErr != nil {
 			var nfErr *store.ErrNotFound
 			switch {
@@ -756,6 +774,7 @@ func (a *App) RestoreChannel(c *request.Context, channel *model.Channel, userID
 				return nil, model.NewAppError("RestoreChannel", "app.user.get.app_error", nil, nErr.Error(), http.StatusInternalServerError)
 			}
 		}
+	}
 
 	if user != nil {
 		T := i18n.GetUserTranslations(user.Locale)
@@ -773,6 +792,28 @@ func (a *App) RestoreChannel(c *request.Context, channel *model.Channel, userID
 		if _, err := a.CreatePost(c, post, channel, false, true); err != nil {
 			mlog.Warn("Failed to post unarchive message", mlog.Err(err))
 		}
+	} else {
+		a.Srv().Go(func() {
+			systemBot, err := a.GetSystemBot()
+			if err != nil {
+				mlog.Error("Failed to post unarchive message", mlog.Err(err))
+				return
+			}
+
+			post := &model.Post{
+				ChannelId: channel.Id,
+				Message:   i18n.T("api.channel.restore_channel.unarchived", map[string]interface{}{"Username": systemBot.Username}),
+				Type:      model.POST_CHANNEL_RESTORED,
+				UserId:    systemBot.UserId,
+				Props: model.StringInterface{
+					"username": systemBot.Username,
+				},
+			}
+
+			if _, err := a.CreatePost(c, post, channel, false, true); err != nil {
+				mlog.Error("Failed to post unarchive message", mlog.Err(err))
+			}
+		})
 	}
 
 	return channel, nil
@@ -1297,6 +1338,28 @@ func (a *App) DeleteChannel(c *request.Context, channel *model.Channel, userID s
 		if _, err := a.CreatePost(c, post, channel, false, true); err != nil {
 			mlog.Warn("Failed to post archive message", mlog.Err(err))
 		}
+	} else {
+		a.Srv().Go(func() {
+			systemBot, err := a.GetSystemBot()
+			if err != nil {
+				mlog.Error("Failed to post archive message", mlog.Err(err))
+				return
+			}
+
+			post := &model.Post{
+				ChannelId: channel.Id,
+				Message:   fmt.Sprintf(i18n.T("api.channel.delete_channel.archived"), systemBot.Username),
+				Type:      model.POST_CHANNEL_DELETED,
+				UserId:    systemBot.UserId,
+				Props: model.StringInterface{
+					"username": systemBot.Username,
+				},
+			}
+
+			if _, err := a.CreatePost(c, post, channel, false, true); err != nil {
+				mlog.Error("Failed to post archive message", mlog.Err(err))
+			}
+		})
 	}
 
 	now := model.GetMillis()
@@ -1468,7 +1531,9 @@ func (a *App) AddChannelMember(c *request.Context, userID string, channel *model
 	}
 
 	if opts.UserRequestorID == "" || userID == opts.UserRequestorID {
-		a.postJoinChannelMessage(c, user, channel)
+		if err := a.postJoinChannelMessage(c, user, channel); err != nil {
+			mlog.Error("Failed to post join channel message", mlog.Err(err))
+		}
 	} else {
 		a.Srv().Go(func() {
 			a.PostAddToChannelMessage(c, userRequestor, user, channel, opts.PostRootID)
@@ -2179,6 +2244,16 @@ func (a *App) postAddToTeamMessage(c *request.Context, user *model.User, addedUs
 }
 
 func (a *App) postRemoveFromChannelMessage(c *request.Context, removerUserId string, removedUser *model.User, channel *model.Channel) *model.AppError {
+	messageUserId := removerUserId
+	if messageUserId == "" {
+		systemBot, err := a.GetSystemBot()
+		if err != nil {
+			return model.NewAppError("postRemoveFromChannelMessage", "api.channel.post_user_add_remove_message_and_forget.error", nil, err.Error(), http.StatusInternalServerError)
+		}
+
+		messageUserId = systemBot.UserId
+	}
+
 	post := &model.Post{
 		ChannelId: channel.Id,
 		// Message here embeds `@username`, not just `username`, to ensure that mentions
@@ -2186,7 +2261,7 @@ func (a *App) postRemoveFromChannelMessage(c *request.Context, removerUserId str
 		// The client renders its own system message, ignoring this value altogether.
 		Message: fmt.Sprintf(i18n.T("api.channel.remove_member.removed"), fmt.Sprintf("@%s", removedUser.Username)),
 		Type:    model.POST_REMOVE_FROM_CHANNEL,
-		UserId:  removerUserId,
+		UserId:  messageUserId,
 		Props: model.StringInterface{
 			"removedUserId":   removedUser.Id,
 			"removedUsername": removedUser.Username,
@@ -2308,7 +2383,9 @@ func (a *App) RemoveUserFromChannel(c *request.Context, userIDToRemove string, r
 		}
 	} else {
 		a.Srv().Go(func() {
-			a.postRemoveFromChannelMessage(c, removerUserId, user, channel)
+			if err := a.postRemoveFromChannelMessage(c, removerUserId, user, channel); err != nil {
+				mlog.Error("Failed to post user removal message", mlog.Err(err))
+			}
 		})
 	}
 

app/opentracing/opentracing_layer.go

@@ -8809,6 +8809,28 @@ func (a *OpenTracingAppLayer) GetSuggestions(c *request.Context, commandArgs *mo
 	return resultVar0
 }
 
+func (a *OpenTracingAppLayer) GetSystemBot() (*model.Bot, *model.AppError) {
+	origCtx := a.ctx
+	span, newCtx := tracing.StartSpanWithParentByContext(a.ctx, "app.GetSystemBot")
+
+	a.ctx = newCtx
+	a.app.Srv().Store.SetContext(newCtx)
+	defer func() {
+		a.app.Srv().Store.SetContext(origCtx)
+		a.ctx = origCtx
+	}()
+
+	defer span.Finish()
+	resultVar0, resultVar1 := a.app.GetSystemBot()
+
+	if resultVar1 != nil {
+		span.LogFields(spanlog.Error(resultVar1))
+		ext.Error.Set(span, true)
+	}
+
+	return resultVar0, resultVar1
+}
+
 func (a *OpenTracingAppLayer) GetTeam(teamID string) (*model.Team, *model.AppError) {
 	origCtx := a.ctx
 	span, newCtx := tracing.StartSpanWithParentByContext(a.ctx, "app.GetTeam")
@@ -10136,6 +10158,28 @@ func (a *OpenTracingAppLayer) GetViewUsersRestrictions(userID string) (*model.Vi
 	return resultVar0, resultVar1
 }
 
+func (a *OpenTracingAppLayer) GetWarnMetricsBot() (*model.Bot, *model.AppError) {
+	origCtx := a.ctx
+	span, newCtx := tracing.StartSpanWithParentByContext(a.ctx, "app.GetWarnMetricsBot")
+
+	a.ctx = newCtx
+	a.app.Srv().Store.SetContext(newCtx)
+	defer func() {
+		a.app.Srv().Store.SetContext(origCtx)
+		a.ctx = origCtx
+	}()
+
+	defer span.Finish()
+	resultVar0, resultVar1 := a.app.GetWarnMetricsBot()
+
+	if resultVar1 != nil {
+		span.LogFields(spanlog.Error(resultVar1))
+		ext.Error.Set(span, true)
+	}
+
+	return resultVar0, resultVar1
+}
+
 func (a *OpenTracingAppLayer) GetWarnMetricsStatus() (map[string]*model.WarnMetricStatus, *model.AppError) {
 	origCtx := a.ctx
 	span, newCtx := tracing.StartSpanWithParentByContext(a.ctx, "app.GetWarnMetricsStatus")

i18n/en.json

@@ -4366,6 +4366,14 @@
     "id": "app.bot.get_disable_bot_sysadmin_message",
     "translation": "{{if .disableBotsSetting}}{{if .printAllBots}}{{.UserName}} was deactivated. They managed the following bot accounts which have now been disabled.\n\n{{.BotNames}}{{else}}{{.UserName}} was deactivated. They managed {{.NumBots}} bot accounts which have now been disabled, including the following:\n\n{{.BotNames}}{{end}}You can take ownership of each bot by enabling it at **Integrations > Bot Accounts** and creating new tokens for the bot.\n\nFor more information, see our [documentation](https://docs.mattermost.com/developer/bot-accounts.html#what-happens-when-a-user-who-owns-bot-accounts-is-disabled).{{else}}{{if .printAllBots}}{{.UserName}} was deactivated. They managed the following bot accounts which are still enabled.\n\n{{.BotNames}}\n{{else}}{{.UserName}} was deactivated. They managed {{.NumBots}} bot accounts which are still enabled, including the following:\n\n{{.BotNames}}{{end}}We strongly recommend you to take ownership of each bot by re-enabling it at **Integrations > Bot Accounts** and creating new tokens for the bot.\n\nFor more information, see our [documentation](https://docs.mattermost.com/developer/bot-accounts.html#what-happens-when-a-user-who-owns-bot-accounts-is-disabled).\n\nIf you want bot accounts to disable automatically after owner deactivation, set “Disable bot accounts when owner is deactivated” in **System Console > Integrations > Bot Accounts** to true.{{end}}"
   },
+  {
+    "id": "app.bot.get_system_bot.empty_admin_list.app_error",
+    "translation": "List of admins is empty."
+  },
+  {
+    "id": "app.bot.get_warn_metrics_bot.empty_admin_list.app_error",
+    "translation": "List of admins is empty."
+  },
   {
     "id": "app.bot.getbot.internal_error",
     "translation": "Unable to get the bot."
@@ -6018,6 +6026,10 @@
     "id": "app.system.save.app_error",
     "translation": "We encountered an error saving the system property."
   },
+  {
+    "id": "app.system.system_bot.bot_displayname",
+    "translation": "System"
+  },
   {
     "id": "app.system.warn_metric.bot_description",
     "translation": "[Learn more about the Mattermost Advisor](https://about.mattermost.com/default-channel-handle-documentation)"

model/bot.go

@@ -17,6 +17,7 @@ const (
 	BOT_DESCRIPTION_MAX_RUNES    = 1024
 	BOT_CREATOR_ID_MAX_RUNES     = KEY_VALUE_PLUGIN_ID_MAX_RUNES // UserId or PluginId
 	BOT_WARN_METRIC_BOT_USERNAME = "mattermost-advisor"
+	BOT_SYSTEM_BOT_USERNAME      = "system-bot"
 )
 
 // Bot is a special type of User meant for programmatic interactions.