Improve bulk export logging (#21935)

This change includes the following:
 - Adds the job ID as a log field for bulk exports
 - Adds checkpoint logging for posts and direct posts so that
   progress can be tracked.

app/export.go

@@ -398,8 +398,15 @@ func (a *App) buildUserNotifyProps(notifyProps model.StringMap) *imports.UserNot
 func (a *App) exportAllPosts(ctx request.CTX, writer io.Writer, withAttachments bool) ([]imports.AttachmentImportData, *model.AppError) {
 	var attachments []imports.AttachmentImportData
 	afterId := strings.Repeat("0", 26)
+	var postProcessCount uint64
+	logCheckpoint := time.Now()
 
 	for {
+		if time.Since(logCheckpoint) > 5*time.Minute {
+			ctx.Logger().Debug(fmt.Sprintf("Bulk Export: processed %d posts", postProcessCount))
+			logCheckpoint = time.Now()
+		}
+
 		posts, nErr := a.Srv().Store().Post().GetParentsForExportAfter(1000, afterId)
 		if nErr != nil {
 			return nil, model.NewAppError("exportAllPosts", "app.post.get_posts.app_error", nil, "", http.StatusInternalServerError).Wrap(nErr)
@@ -411,6 +418,7 @@ func (a *App) exportAllPosts(ctx request.CTX, writer io.Writer, withAttachments
 
 		for _, post := range posts {
 			afterId = post.Id
+			postProcessCount++
 
 			// Skip deleted.
 			if post.DeleteAt != 0 {
@@ -677,7 +685,15 @@ func (a *App) buildFavoritedByList(channelID string) ([]string, *model.AppError)
 func (a *App) exportAllDirectPosts(ctx request.CTX, writer io.Writer, withAttachments bool) ([]imports.AttachmentImportData, *model.AppError) {
 	var attachments []imports.AttachmentImportData
 	afterId := strings.Repeat("0", 26)
+	var postProcessCount uint64
+	logCheckpoint := time.Now()
+
 	for {
+		if time.Since(logCheckpoint) > 5*time.Minute {
+			ctx.Logger().Debug(fmt.Sprintf("Bulk Export: processed %d direct posts", postProcessCount))
+			logCheckpoint = time.Now()
+		}
+
 		posts, err := a.Srv().Store().Post().GetDirectPostParentsForExportAfter(1000, afterId)
 		if err != nil {
 			return nil, model.NewAppError("exportAllDirectPosts", "app.post.get_direct_posts.app_error", nil, "", http.StatusInternalServerError).Wrap(err)
@@ -689,6 +705,7 @@ func (a *App) exportAllDirectPosts(ctx request.CTX, writer io.Writer, withAttach
 
 		for _, post := range posts {
 			afterId = post.Id
+			postProcessCount++
 
 			// Skip deleted.
 			if post.DeleteAt != 0 {