PLT-7503: Create Message Export Scheduled Task and CLI Command (#7612)

* Created message export scheduled task

* Added CLI command to immediately kick off an export job

* Added email addresses for users joining and leaving the channel to the export

* Added support for both MySQL and PostgreSQL

* Fixing gofmt error

* Added a new ChannelMemberHistory store and associated tests

* Updating the ChannelMemberHistory channel as users create/join/leave channels

* Added user email to the message export object so it can be included in the actiance export xml

* Don't fail to log a leave event if a corresponding join event wasn't logged

* Adding copyright notices

* Adding message export settings to daily diagnostics report

* Added System Console integration for message export

* Cleaned up TODOs

* Made batch size configurable

* Added export from timestamp to CLI command

* Made ChannelMemberHistory table updates best effort

* Added a context-based timeout option to the message export CLI

* Minor PR updates/improvements

* Removed unnecessary fields from MessageExport object to reduce query overhead

* Removed JSON functions from the message export query in an effort to optimize performance

* Changed the way that channel member history queries and purges work to better account for edge cases

* Fixing a test I missed with the last refactor

* Added file copy functionality to file backend, improved config validation, added default config values

* Fixed file copy tests

* More concise use of the testing libraries

* Fixed context leak error

* Changed default export path to correctly place an 'export' directory under the 'data' directory

* Can't delete records from a read replica

* Fixed copy file tests

* Start job workers when license is applied, if configured to do so

* Suggestions from the PR

* Moar unit tests

* Fixed test imports

app/channel.go

@@ -49,12 +49,19 @@ func (a *App) JoinDefaultChannels(teamId string, user *model.User, channelRole s
 	} else {
 		townSquare := result.Data.(*model.Channel)
 
-		cm := &model.ChannelMember{ChannelId: townSquare.Id, UserId: user.Id,
-			Roles: channelRole, NotifyProps: model.GetDefaultChannelNotifyProps()}
+		cm := &model.ChannelMember{
+			ChannelId:   townSquare.Id,
+			UserId:      user.Id,
+			Roles:       channelRole,
+			NotifyProps: model.GetDefaultChannelNotifyProps(),
+		}
 
 		if cmResult := <-a.Srv.Store.Channel().SaveMember(cm); cmResult.Err != nil {
 			err = cmResult.Err
 		}
+		if result := <-a.Srv.Store.ChannelMemberHistory().LogJoinEvent(user.Id, townSquare.Id, model.GetMillis()); result.Err != nil {
+			l4g.Warn("Failed to update ChannelMemberHistory table %v", result.Err)
+		}
 
 		if requestor == nil {
 			if err := a.postJoinChannelMessage(user, townSquare); err != nil {
@@ -74,12 +81,19 @@ func (a *App) JoinDefaultChannels(teamId string, user *model.User, channelRole s
 	} else {
 		offTopic := result.Data.(*model.Channel)
 
-		cm := &model.ChannelMember{ChannelId: offTopic.Id, UserId: user.Id,
-			Roles: channelRole, NotifyProps: model.GetDefaultChannelNotifyProps()}
+		cm := &model.ChannelMember{
+			ChannelId:   offTopic.Id,
+			UserId:      user.Id,
+			Roles:       channelRole,
+			NotifyProps: model.GetDefaultChannelNotifyProps(),
+		}
 
 		if cmResult := <-a.Srv.Store.Channel().SaveMember(cm); cmResult.Err != nil {
 			err = cmResult.Err
 		}
+		if result := <-a.Srv.Store.ChannelMemberHistory().LogJoinEvent(user.Id, offTopic.Id, model.GetMillis()); result.Err != nil {
+			l4g.Warn("Failed to update ChannelMemberHistory table %v", result.Err)
+		}
 
 		if requestor == nil {
 			if err := a.postJoinChannelMessage(user, offTopic); err != nil {
@@ -158,6 +172,9 @@ func (a *App) CreateChannel(channel *model.Channel, addMember bool) (*model.Chan
 			if cmresult := <-a.Srv.Store.Channel().SaveMember(cm); cmresult.Err != nil {
 				return nil, cmresult.Err
 			}
+			if result := <-a.Srv.Store.ChannelMemberHistory().LogJoinEvent(channel.CreatorId, sc.Id, model.GetMillis()); result.Err != nil {
+				l4g.Warn("Failed to update ChannelMemberHistory table %v", result.Err)
+			}
 
 			a.InvalidateCacheForUser(channel.CreatorId)
 		}
@@ -302,6 +319,9 @@ func (a *App) createGroupChannel(userIds []string, creatorId string) (*model.Cha
 			if result := <-a.Srv.Store.Channel().SaveMember(cm); result.Err != nil {
 				return nil, result.Err
 			}
+			if result := <-a.Srv.Store.ChannelMemberHistory().LogJoinEvent(user.Id, channel.Id, model.GetMillis()); result.Err != nil {
+				l4g.Warn("Failed to update ChannelMemberHistory table %v", result.Err)
+			}
 		}
 
 		return channel, nil
@@ -520,9 +540,12 @@ func (a *App) addUserToChannel(user *model.User, channel *model.Channel, teamMem
 		l4g.Error("Failed to add member user_id=%v channel_id=%v err=%v", user.Id, channel.Id, result.Err)
 		return nil, model.NewAppError("AddUserToChannel", "api.channel.add_user.to.channel.failed.app_error", nil, "", http.StatusInternalServerError)
 	}
-
 	a.WaitForChannelMembership(channel.Id, user.Id)
 
+	if result := <-a.Srv.Store.ChannelMemberHistory().LogJoinEvent(user.Id, channel.Id, model.GetMillis()); result.Err != nil {
+		l4g.Warn("Failed to update ChannelMemberHistory table %v", result.Err)
+	}
+
 	a.InvalidateCacheForUser(user.Id)
 	a.InvalidateCacheForChannelMembers(channel.Id)
 
@@ -1069,6 +1092,9 @@ func (a *App) removeUserFromChannel(userIdToRemove string, removerUserId string,
 	if cmresult := <-a.Srv.Store.Channel().RemoveMember(channel.Id, userIdToRemove); cmresult.Err != nil {
 		return cmresult.Err
 	}
+	if cmhResult := <-a.Srv.Store.ChannelMemberHistory().LogLeaveEvent(userIdToRemove, channel.Id, model.GetMillis()); cmhResult.Err != nil {
+		return cmhResult.Err
+	}
 
 	a.InvalidateCacheForUser(userIdToRemove)
 	a.InvalidateCacheForChannelMembers(channel.Id)