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

jobs/workers.go

@@ -17,6 +17,7 @@ type Workers struct {
 	Watcher   *Watcher
 
 	DataRetention            model.Worker
+	MessageExport            model.Worker
 	ElasticsearchIndexing    model.Worker
 	ElasticsearchAggregation model.Worker
 	LdapSync                 model.Worker
@@ -34,6 +35,10 @@ func (srv *JobServer) InitWorkers() *Workers {
 		workers.DataRetention = srv.DataRetentionJob.MakeWorker()
 	}
 
+	if srv.MessageExportJob != nil {
+		workers.MessageExport = srv.MessageExportJob.MakeWorker()
+	}
+
 	if elasticsearchIndexerInterface := srv.ElasticsearchIndexer; elasticsearchIndexerInterface != nil {
 		workers.ElasticsearchIndexing = elasticsearchIndexerInterface.MakeWorker()
 	}
@@ -57,6 +62,10 @@ func (workers *Workers) Start() *Workers {
 			go workers.DataRetention.Run()
 		}
 
+		if workers.MessageExport != nil && *workers.Config().MessageExportSettings.EnableExport {
+			go workers.MessageExport.Run()
+		}
+
 		if workers.ElasticsearchIndexing != nil && *workers.Config().ElasticsearchSettings.EnableIndexing {
 			go workers.ElasticsearchIndexing.Run()
 		}
@@ -86,6 +95,14 @@ func (workers *Workers) handleConfigChange(oldConfig *model.Config, newConfig *m
 		}
 	}
 
+	if workers.MessageExport != nil {
+		if !*oldConfig.MessageExportSettings.EnableExport && *newConfig.MessageExportSettings.EnableExport {
+			go workers.MessageExport.Run()
+		} else if *oldConfig.MessageExportSettings.EnableExport && !*newConfig.MessageExportSettings.EnableExport {
+			workers.MessageExport.Stop()
+		}
+	}
+
 	if workers.ElasticsearchIndexing != nil {
 		if !*oldConfig.ElasticsearchSettings.EnableIndexing && *newConfig.ElasticsearchSettings.EnableIndexing {
 			go workers.ElasticsearchIndexing.Run()
@@ -120,6 +137,10 @@ func (workers *Workers) Stop() *Workers {
 		workers.DataRetention.Stop()
 	}
 
+	if workers.MessageExport != nil && *workers.Config().MessageExportSettings.EnableExport {
+		workers.MessageExport.Stop()
+	}
+
 	if workers.ElasticsearchIndexing != nil && *workers.Config().ElasticsearchSettings.EnableIndexing {
 		workers.ElasticsearchIndexing.Stop()
 	}