MM-40818: Pass filestore to channels (#19677)

We move away from referencing server struct
but pass the filestore service to Channels
explicitly.

https://mattermost.atlassian.net/browse/MM-40818

```release-note
NONE
```

Co-authored-by: Mattermod <mattermod@users.noreply.github.com>

app/channels.go

@@ -17,6 +17,7 @@ import (
 	"github.com/mattermost/mattermost-server/v6/model"
 	"github.com/mattermost/mattermost-server/v6/plugin"
 	"github.com/mattermost/mattermost-server/v6/services/imageproxy"
+	"github.com/mattermost/mattermost-server/v6/shared/filestore"
 	"github.com/mattermost/mattermost-server/v6/shared/mlog"
 	"github.com/pkg/errors"
 )
@@ -48,6 +49,7 @@ type namer interface {
 type Channels struct {
 	srv        *Server
 	cfgSvc     configSvc
+	filestore  filestore.FileBackend
 	licenseSvc licenseSvc
 
 	postActionCookieSecret []byte
@@ -115,6 +117,7 @@ func NewChannels(s *Server, services map[ServiceKey]interface{}) (*Channels, err
 	requiredServices := []ServiceKey{
 		ConfigKey,
 		LicenseKey,
+		FilestoreKey,
 	}
 	for _, svcKey := range requiredServices {
 		svc, ok := services[svcKey]
@@ -133,6 +136,12 @@ func NewChannels(s *Server, services map[ServiceKey]interface{}) (*Channels, err
 				return nil, errors.New("Config service does not contain Name method")
 			}
 			ch.cfgSvc = cfgSvc
+		case FilestoreKey:
+			filestore, ok := svc.(filestore.FileBackend)
+			if !ok {
+				return nil, errors.New("Filestore service did not satisfy FileBackend interface")
+			}
+			ch.filestore = filestore
 		case LicenseKey:
 			svc, ok := svc.(licenseSvc)
 			if !ok {

app/file.go

@@ -48,7 +48,7 @@ const (
 )
 
 func (a *App) FileBackend() filestore.FileBackend {
-	return a.Srv().FileBackend()
+	return a.ch.filestore
 }
 
 func (a *App) CheckMandatoryS3Fields(settings *model.FileSettings) *model.AppError {

app/notification_push_test.go

@@ -19,6 +19,7 @@ import (
 
 	"github.com/mattermost/mattermost-server/v6/config"
 	"github.com/mattermost/mattermost-server/v6/model"
+	fmocks "github.com/mattermost/mattermost-server/v6/shared/filestore/mocks"
 	"github.com/mattermost/mattermost-server/v6/shared/i18n"
 	"github.com/mattermost/mattermost-server/v6/store/storetest/mocks"
 	"github.com/mattermost/mattermost-server/v6/testlib"
@@ -1428,14 +1429,16 @@ func TestPushNotificationRace(t *testing.T) {
 		Return(&model.Preference{Value: "test"}, nil)
 	mockStore.On("Preference").Return(&mockPreferenceStore)
 	s := &Server{
-		Store:    mockStore,
-		products: make(map[string]Product),
-		Router:   mux.NewRouter(),
+		Store:     mockStore,
+		products:  make(map[string]Product),
+		Router:    mux.NewRouter(),
+		filestore: &fmocks.FileBackend{},
 	}
 	s.configStore = &configWrapper{srv: s, Store: memoryStore}
 	serviceMap := map[ServiceKey]interface{}{
-		ConfigKey:  s.configStore,
-		LicenseKey: &licenseWrapper{s},
+		ConfigKey:    s.configStore,
+		LicenseKey:   &licenseWrapper{s},
+		FilestoreKey: s.filestore,
 	}
 	ch, err := NewChannels(s, serviceMap)
 	require.NoError(t, err)

app/options.go

@@ -9,6 +9,7 @@ import (
 	"github.com/mattermost/mattermost-server/v6/config"
 	"github.com/mattermost/mattermost-server/v6/einterfaces"
 	"github.com/mattermost/mattermost-server/v6/model"
+	"github.com/mattermost/mattermost-server/v6/shared/filestore"
 	"github.com/mattermost/mattermost-server/v6/shared/mlog"
 	"github.com/mattermost/mattermost-server/v6/store"
 )
@@ -65,6 +66,13 @@ func ConfigStore(configStore *config.Store) Option {
 	}
 }
 
+func SetFileStore(filestore filestore.FileBackend) Option {
+	return func(s *Server) error {
+		s.filestore = filestore
+		return nil
+	}
+}
+
 func RunEssentialJobs(s *Server) error {
 	s.runEssentialJobs = true
 

app/server.go

@@ -89,8 +89,9 @@ var SentryDSN = "placeholder_sentry_dsn"
 type ServiceKey string
 
 const (
-	ConfigKey  ServiceKey = "config"
-	LicenseKey ServiceKey = "license"
+	ConfigKey    ServiceKey = "config"
+	LicenseKey   ServiceKey = "license"
+	FilestoreKey ServiceKey = "filestore"
 )
 
 type Server struct {
@@ -362,8 +363,9 @@ func NewServer(options ...Option) (*Server, error) {
 	}
 
 	serviceMap := map[ServiceKey]interface{}{
-		ConfigKey:  s.configStore,
-		LicenseKey: s.licenseWrapper,
+		ConfigKey:    s.configStore,
+		LicenseKey:   s.licenseWrapper,
+		FilestoreKey: s.filestore,
 	}
 	// Step 8: Initialize products.
 	// Depends on s.httpService.