MM-53747: Create job to encode older image paths (#24073)

Bifrost now encodes all image paths. Due to this
one-way translation, we need to encode all the older
image paths as well.

After this is done, we can remove the double-lookup.

https://mattermost.atlassian.net/browse/MM-53747

```release-note
NONE
```

Co-authored-by: Mattermost Build <build@mattermost.com>

server/channels/app/migrations.go

@@ -6,6 +6,7 @@ package app
 import (
 	"context"
 	"fmt"
+	"os"
 	"reflect"
 
 	"github.com/mattermost/mattermost/server/public/model"
@@ -571,6 +572,35 @@ func (s *Server) doElasticsearchFixChannelIndex() {
 	}
 }
 
+func (s *Server) doCloudS3PathMigrations() {
+	// This migration is only applicable for cloud environments
+	if os.Getenv("MM_CLOUD_FILESTORE_BIFROST") == "" {
+		return
+	}
+
+	// If the migration is already marked as completed, don't do it again.
+	if _, err := s.Store().System().GetByName(model.MigrationKeyS3Path); err == nil {
+		return
+	}
+
+	// If there is a job already pending, no need to schedule again.
+	// This is possible if the pod was rolled over.
+	jobs, err := s.Store().Job().GetAllByTypeAndStatus(model.JobTypeS3PathMigration, model.JobStatusPending)
+	if err != nil {
+		mlog.Fatal("failed to get jobs by type and status", mlog.Err(err))
+		return
+	}
+	if len(jobs) > 0 {
+		return
+	}
+
+	if _, appErr := s.Jobs.CreateJob(model.JobTypeS3PathMigration, nil); appErr != nil {
+		mlog.Fatal("failed to start job for migrating s3 file paths", mlog.Err(appErr))
+		return
+	}
+
+}
+
 func (a *App) DoAppMigrations() {
 	a.Srv().doAppMigrations()
 }
@@ -593,4 +623,5 @@ func (s *Server) doAppMigrations() {
 	s.doRemainingSchemaMigrations()
 	s.doPostPriorityConfigDefaultTrueMigration()
 	s.doElasticsearchFixChannelIndex()
+	s.doCloudS3PathMigrations()
 }

server/channels/app/server.go

@@ -54,6 +54,7 @@ import (
 	"github.com/mattermost/mattermost/server/v8/channels/jobs/post_persistent_notifications"
 	"github.com/mattermost/mattermost/server/v8/channels/jobs/product_notices"
 	"github.com/mattermost/mattermost/server/v8/channels/jobs/resend_invitation_email"
+	"github.com/mattermost/mattermost/server/v8/channels/jobs/s3_path_migration"
 	"github.com/mattermost/mattermost/server/v8/channels/product"
 	"github.com/mattermost/mattermost/server/v8/channels/store"
 	"github.com/mattermost/mattermost/server/v8/channels/utils"
@@ -1568,6 +1569,11 @@ func (s *Server) initJobs() {
 		import_delete.MakeScheduler(s.Jobs),
 	)
 
+	s.Jobs.RegisterJobType(
+		model.JobTypeS3PathMigration,
+		s3_path_migration.MakeWorker(s.Jobs, s.Store(), s.FileBackend()),
+		nil)
+
 	s.Jobs.RegisterJobType(
 		model.JobTypeExportDelete,
 		export_delete.MakeWorker(s.Jobs, New(ServerConnector(s.Channels()))),