[feature] Start implementing refetch of lost media files via `/api/v1/admin/media_refetch` (#1221)

* [chore] Move ShortcodeDomain to its own little util func * [feature] Add RefetchEmojis function to media manager * [feature] Expose admin media refresh via admin API * update following review feedback - change/fix log levels - make sure not to try to refetch local emojis - small style refactoring + comments * log on emoji refetch start Signed-off-by: kim <grufwub@gmail.com> Co-authored-by: kim <grufwub@gmail.com>
2022-12-10 22:43:11 +01:00 · 2022-12-10 22:43:11 +01:00 · 5e060d0bcb
parent 24b4f9b5d7
commit 5e060d0bcb
13 changed files with 499 additions and 28 deletions
--- a/docs/api/swagger.yaml
+++ b/docs/api/swagger.yaml
@ -3209,6 +3209,40 @@ paths:
            summary: Clean up remote media older than the specified number of days.
            tags:
                - admin
+    /api/v1/admin/media_refetch:
+        post:
+            description: |-
+                Currently, this only includes remote emojis.
+                This endpoint is useful when data loss has occurred, and you want to try to recover to a working state.
+            operationId: mediaRefetch
+            parameters:
+                - description: Domain to refetch media from. If empty, all domains will be refetched.
+                  in: query
+                  name: domain
+                  type: string
+            produces:
+                - application/json
+            responses:
+                "202":
+                    description: Request accepted and will be processed. Check the logs for progress / errors.
+                "400":
+                    description: bad request
+                "401":
+                    description: unauthorized
+                "403":
+                    description: forbidden
+                "404":
+                    description: not found
+                "406":
+                    description: not acceptable
+                "500":
+                    description: internal server error
+            security:
+                - OAuth2 Bearer:
+                    - admin
+            summary: Refetch media specified in the database but missing from storage.
+            tags:
+                - admin
    /api/v1/apps:
        post:
            consumes:
--- a/internal/api/client/admin/admin.go
+++ b/internal/api/client/admin/admin.go
@ -46,6 +46,7 @@ const (
 	// AccountsActionPath is used for taking action on a single account.
 	AccountsActionPath = AccountsPathWithID + "/action"
 	MediaCleanupPath   = BasePath + "/media_cleanup"
+	MediaRefetchPath   = BasePath + "/media_refetch"

 	// ExportQueryKey is for requesting a public export of some data.
 	ExportQueryKey = "export"
@ -63,6 +64,8 @@ const (
 	MinShortcodeDomainKey = "min_shortcode_domain"
 	// LimitKey is for specifying maximum number of results to return.
 	LimitKey = "limit"
+	// DomainQueryKey is for specifying a domain during admin actions.
+	DomainQueryKey = "domain"
 )

 // Module implements the ClientAPIModule interface for admin-related actions (reports, emojis, etc)
@ -90,6 +93,7 @@ func (m *Module) Route(r router.Router) error {
 	r.AttachHandler(http.MethodDelete, DomainBlocksPathWithID, m.DomainBlockDELETEHandler)
 	r.AttachHandler(http.MethodPost, AccountsActionPath, m.AccountActionPOSTHandler)
 	r.AttachHandler(http.MethodPost, MediaCleanupPath, m.MediaCleanupPOSTHandler)
+	r.AttachHandler(http.MethodPost, MediaRefetchPath, m.MediaRefetchPOSTHandler)
 	r.AttachHandler(http.MethodGet, EmojiCategoriesPath, m.EmojiCategoriesGETHandler)
 	return nil
 }
--- a/internal/api/client/admin/mediarefetch.go
+++ b/internal/api/client/admin/mediarefetch.go
@ -0,0 +1,93 @@
+/*
+   GoToSocial
+   Copyright (C) 2021-2022 GoToSocial Authors admin@gotosocial.org
+
+   This program is free software: you can redistribute it and/or modify
+   it under the terms of the GNU Affero General Public License as published by
+   the Free Software Foundation, either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU Affero General Public License for more details.
+
+   You should have received a copy of the GNU Affero General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+package admin
+
+import (
+	"fmt"
+	"net/http"
+
+	"github.com/gin-gonic/gin"
+	"github.com/superseriousbusiness/gotosocial/internal/api"
+	"github.com/superseriousbusiness/gotosocial/internal/gtserror"
+	"github.com/superseriousbusiness/gotosocial/internal/oauth"
+)
+
+// MediaRefetchPOSTHandler swagger:operation POST /api/v1/admin/media_refetch mediaRefetch
+//
+// Refetch media specified in the database but missing from storage.
+// Currently, this only includes remote emojis.
+// This endpoint is useful when data loss has occurred, and you want to try to recover to a working state.
+//
+//	---
+//	tags:
+//	- admin
+//
+//	produces:
+//	- application/json
+//
+//	security:
+//	- OAuth2 Bearer:
+//		- admin
+//
+//	parameters:
+//	-
+//		name: domain
+//		in: query
+//		description: >-
+//			Domain to refetch media from.
+//			If empty, all domains will be refetched.
+//		type: string
+//
+//	responses:
+//		'202':
+//			description: >-
+//				Request accepted and will be processed.
+//				Check the logs for progress / errors.
+//		'400':
+//			description: bad request
+//		'401':
+//			description: unauthorized
+//		'403':
+//			description: forbidden
+//		'404':
+//			description: not found
+//		'406':
+//			description: not acceptable
+//		'500':
+//			description: internal server error
+func (m *Module) MediaRefetchPOSTHandler(c *gin.Context) {
+	authed, err := oauth.Authed(c, true, true, true, true)
+	if err != nil {
+		api.ErrorHandler(c, gtserror.NewErrorUnauthorized(err, err.Error()), m.processor.InstanceGet)
+		return
+	}
+
+	if !*authed.User.Admin {
+		err := fmt.Errorf("user %s not an admin", authed.User.ID)
+		api.ErrorHandler(c, gtserror.NewErrorForbidden(err, err.Error()), m.processor.InstanceGet)
+		return
+	}
+
+	if errWithCode := m.processor.AdminMediaRefetch(c.Request.Context(), authed, c.Query(DomainQueryKey)); errWithCode != nil {
+		api.ErrorHandler(c, errWithCode, m.processor.InstanceGet)
+		return
+	}
+
+	c.Status(http.StatusAccepted)
+}
--- a/internal/media/manager.go
+++ b/internal/media/manager.go
@ -40,6 +40,15 @@ const UnusedLocalAttachmentCacheDays = 3

 // Manager provides an interface for managing media: parsing, storing, and retrieving media objects like photos, videos, and gifs.
 type Manager interface {
+	// Stop stops the underlying worker pool of the manager. It should be called
+	// when closing GoToSocial in order to cleanly finish any in-progress jobs.
+	// It will block until workers are finished processing.
+	Stop() error
+
+	/*
+		PROCESSING FUNCTIONS
+	*/
+
 	// ProcessMedia begins the process of decoding and storing the given data as an attachment.
 	// It will return a pointer to a ProcessingMedia struct upon which further actions can be performed, such as getting
 	// the finished media, thumbnail, attachment, etc.
@ -75,6 +84,10 @@ type Manager interface {
 	// RecacheMedia refetches, reprocesses, and recaches an existing attachment that has been uncached via pruneRemote.
 	RecacheMedia(ctx context.Context, data DataFunc, postData PostDataCallbackFunc, attachmentID string) (*ProcessingMedia, error)

+	/*
+		PRUNING FUNCTIONS
+	*/
+
 	// PruneAllRemote prunes all remote media attachments cached on this instance which are older than the given amount of days.
 	// 'Pruning' in this context means removing the locally stored data of the attachment (both thumbnail and full size),
 	// and setting 'cached' to false on the associated attachment.
@ -98,10 +111,18 @@ type Manager interface {
 	// is returned to the caller.
 	PruneOrphaned(ctx context.Context, dry bool) (int, error)

-	// Stop stops the underlying worker pool of the manager. It should be called
-	// when closing GoToSocial in order to cleanly finish any in-progress jobs.
-	// It will block until workers are finished processing.
-	Stop() error
+	/*
+		REFETCHING FUNCTIONS
+		Useful when data loss has occurred.
+	*/
+
+	// RefetchEmojis iterates through remote emojis (for the given domain, or all if domain is empty string).
+	//
+	// For each emoji, the manager will check whether both the full size and static images are present in storage.
+	// If not, the manager will refetch and reprocess full size and static images for the emoji.
+	//
+	// The provided DereferenceMedia function will be used when it's necessary to refetch something this way.
+	RefetchEmojis(ctx context.Context, domain string, dereferenceMedia DereferenceMedia) (int, error)
 }

 type manager struct {
--- a/internal/media/media_test.go
+++ b/internal/media/media_test.go
@ -20,22 +20,26 @@ package media_test

 import (
 	"github.com/stretchr/testify/suite"
+	"github.com/superseriousbusiness/gotosocial/internal/concurrency"
 	"github.com/superseriousbusiness/gotosocial/internal/db"
 	gtsmodel "github.com/superseriousbusiness/gotosocial/internal/gtsmodel"
 	"github.com/superseriousbusiness/gotosocial/internal/media"
+	"github.com/superseriousbusiness/gotosocial/internal/messages"
 	"github.com/superseriousbusiness/gotosocial/internal/storage"
+	"github.com/superseriousbusiness/gotosocial/internal/transport"
 	"github.com/superseriousbusiness/gotosocial/testrig"
 )

 type MediaStandardTestSuite struct {
 	suite.Suite

-	db              db.DB
-	storage         *storage.Driver
-	manager         media.Manager
-	testAttachments map[string]*gtsmodel.MediaAttachment
-	testAccounts    map[string]*gtsmodel.Account
-	testEmojis      map[string]*gtsmodel.Emoji
+	db                  db.DB
+	storage             *storage.Driver
+	manager             media.Manager
+	transportController transport.Controller
+	testAttachments     map[string]*gtsmodel.MediaAttachment
+	testAccounts        map[string]*gtsmodel.Account
+	testEmojis          map[string]*gtsmodel.Emoji
 }

 func (suite *MediaStandardTestSuite) SetupSuite() {
@ -53,6 +57,7 @@ func (suite *MediaStandardTestSuite) SetupTest() {
 	suite.testAccounts = testrig.NewTestAccounts()
 	suite.testEmojis = testrig.NewTestEmojis()
 	suite.manager = testrig.NewTestMediaManager(suite.db, suite.storage)
+	suite.transportController = testrig.NewTestTransportController(testrig.NewMockHTTPClient(nil, "../../testrig/media"), suite.db, concurrency.NewWorkerPool[messages.FromFederator](0, 0))
 }

 func (suite *MediaStandardTestSuite) TearDownTest() {
--- a/internal/media/refetch.go
+++ b/internal/media/refetch.go
@ -0,0 +1,149 @@
+/*
+   GoToSocial
+   Copyright (C) 2021-2022 GoToSocial Authors admin@gotosocial.org
+
+   This program is free software: you can redistribute it and/or modify
+   it under the terms of the GNU Affero General Public License as published by
+   the Free Software Foundation, either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU Affero General Public License for more details.
+
+   You should have received a copy of the GNU Affero General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+package media
+
+import (
+	"context"
+	"errors"
+	"fmt"
+	"io"
+	"net/url"
+
+	"github.com/superseriousbusiness/gotosocial/internal/db"
+	"github.com/superseriousbusiness/gotosocial/internal/gtsmodel"
+	"github.com/superseriousbusiness/gotosocial/internal/log"
+	"github.com/superseriousbusiness/gotosocial/internal/util"
+)
+
+type DereferenceMedia func(ctx context.Context, iri *url.URL) (io.ReadCloser, int64, error)
+
+func (m *manager) RefetchEmojis(ctx context.Context, domain string, dereferenceMedia DereferenceMedia) (int, error) {
+	// normalize domain
+	if domain == "" {
+		domain = db.EmojiAllDomains
+	}
+
+	var (
+		maxShortcodeDomain string
+		refetchIDs         []string
+	)
+
+	// page through emojis 20 at a time, looking for those with missing images
+	for {
+		// Fetch next block of emojis from database
+		emojis, err := m.db.GetEmojis(ctx, domain, false, true, "", maxShortcodeDomain, "", 20)
+		if err != nil {
+			if !errors.Is(err, db.ErrNoEntries) {
+				// an actual error has occurred
+				log.Errorf("error fetching emojis from database: %s", err)
+			}
+			break
+		}
+
+		for _, emoji := range emojis {
+			if emoji.Domain == "" {
+				// never try to refetch local emojis
+				continue
+			}
+
+			if refetch, err := m.emojiRequiresRefetch(ctx, emoji); err != nil {
+				// an error here indicates something is wrong with storage, so we should stop
+				return 0, fmt.Errorf("error checking refetch requirement for emoji %s: %w", util.ShortcodeDomain(emoji), err)
+			} else if !refetch {
+				continue
+			}
+
+			refetchIDs = append(refetchIDs, emoji.ID)
+		}
+
+		// Update next maxShortcodeDomain from last emoji
+		maxShortcodeDomain = util.ShortcodeDomain(emojis[len(emojis)-1])
+	}
+
+	// bail early if we've got nothing to do
+	toRefetchCount := len(refetchIDs)
+	if toRefetchCount == 0 {
+		log.Debug("no remote emojis require a refetch")
+		return 0, nil
+	}
+	log.Debugf("%d remote emoji(s) require a refetch, doing that now...", toRefetchCount)
+
+	var totalRefetched int
+	for _, emojiID := range refetchIDs {
+		emoji, err := m.db.GetEmojiByID(ctx, emojiID)
+		if err != nil {
+			// this shouldn't happen--since we know we have the emoji--so return if it does
+			return 0, fmt.Errorf("error getting emoji %s: %w", emojiID, err)
+		}
+		shortcodeDomain := util.ShortcodeDomain(emoji)
+
+		if emoji.ImageRemoteURL == "" {
+			log.Errorf("remote emoji %s could not be refreshed because it has no ImageRemoteURL set", shortcodeDomain)
+			continue
+		}
+
+		emojiImageIRI, err := url.Parse(emoji.ImageRemoteURL)
+		if err != nil {
+			log.Errorf("remote emoji %s could not be refreshed because its ImageRemoteURL (%s) is not a valid uri: %s", shortcodeDomain, emoji.ImageRemoteURL, err)
+			continue
+		}
+
+		dataFunc := func(ctx context.Context) (reader io.ReadCloser, fileSize int64, err error) {
+			return dereferenceMedia(ctx, emojiImageIRI)
+		}
+
+		processingEmoji, err := m.ProcessEmoji(ctx, dataFunc, nil, emoji.Shortcode, emoji.ID, emoji.URI, &AdditionalEmojiInfo{
+			Domain:               &emoji.Domain,
+			ImageRemoteURL:       &emoji.ImageRemoteURL,
+			ImageStaticRemoteURL: &emoji.ImageStaticRemoteURL,
+			Disabled:             emoji.Disabled,
+			VisibleInPicker:      emoji.VisibleInPicker,
+		}, true)
+		if err != nil {
+			log.Errorf("emoji %s could not be refreshed because of an error during processing: %s", shortcodeDomain, err)
+			continue
+		}
+
+		if _, err := processingEmoji.LoadEmoji(ctx); err != nil {
+			log.Errorf("emoji %s could not be refreshed because of an error during loading: %s", shortcodeDomain, err)
+			continue
+		}
+
+		log.Tracef("refetched emoji %s successfully from remote", shortcodeDomain)
+		totalRefetched++
+	}
+
+	return totalRefetched, nil
+}
+
+func (m *manager) emojiRequiresRefetch(ctx context.Context, emoji *gtsmodel.Emoji) (bool, error) {
+	if has, err := m.storage.Has(ctx, emoji.ImagePath); err != nil {
+		return false, err
+	} else if !has {
+		return true, nil
+	}
+
+	if has, err := m.storage.Has(ctx, emoji.ImageStaticPath); err != nil {
+		return false, err
+	} else if !has {
+		return true, nil
+	}
+
+	return false, nil
+}
--- a/internal/media/refetch_test.go
+++ b/internal/media/refetch_test.go
@ -0,0 +1,85 @@
+/*
+   GoToSocial
+   Copyright (C) 2021-2022 GoToSocial Authors admin@gotosocial.org
+
+   This program is free software: you can redistribute it and/or modify
+   it under the terms of the GNU Affero General Public License as published by
+   the Free Software Foundation, either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU Affero General Public License for more details.
+
+   You should have received a copy of the GNU Affero General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+package media_test
+
+import (
+	"context"
+	"testing"
+
+	"github.com/stretchr/testify/suite"
+)
+
+type RefetchTestSuite struct {
+	MediaStandardTestSuite
+}
+
+func (suite *RefetchTestSuite) TestRefetchEmojisNothingToDo() {
+	ctx := context.Background()
+
+	adminAccount := suite.testAccounts["admin_account"]
+	transport, err := suite.transportController.NewTransportForUsername(ctx, adminAccount.Username)
+	if err != nil {
+		suite.FailNow(err.Error())
+	}
+
+	refetched, err := suite.manager.RefetchEmojis(ctx, "", transport.DereferenceMedia)
+	suite.NoError(err)
+	suite.Equal(0, refetched)
+}
+
+func (suite *RefetchTestSuite) TestRefetchEmojis() {
+	ctx := context.Background()
+
+	if err := suite.storage.Delete(ctx, suite.testEmojis["yell"].ImagePath); err != nil {
+		suite.FailNow(err.Error())
+	}
+
+	adminAccount := suite.testAccounts["admin_account"]
+	transport, err := suite.transportController.NewTransportForUsername(ctx, adminAccount.Username)
+	if err != nil {
+		suite.FailNow(err.Error())
+	}
+
+	refetched, err := suite.manager.RefetchEmojis(ctx, "", transport.DereferenceMedia)
+	suite.NoError(err)
+	suite.Equal(1, refetched)
+}
+
+func (suite *RefetchTestSuite) TestRefetchEmojisLocal() {
+	ctx := context.Background()
+
+	// delete the image for a LOCAL emoji
+	if err := suite.storage.Delete(ctx, suite.testEmojis["rainbow"].ImagePath); err != nil {
+		suite.FailNow(err.Error())
+	}
+
+	adminAccount := suite.testAccounts["admin_account"]
+	transport, err := suite.transportController.NewTransportForUsername(ctx, adminAccount.Username)
+	if err != nil {
+		suite.FailNow(err.Error())
+	}
+
+	refetched, err := suite.manager.RefetchEmojis(ctx, "", transport.DereferenceMedia)
+	suite.NoError(err)
+	suite.Equal(0, refetched) // shouldn't refetch anything because local
+}
+
+func TestRefetchTestSuite(t *testing.T) {
+	suite.Run(t, &RefetchTestSuite{})
+}
--- a/internal/processing/admin.go
+++ b/internal/processing/admin.go
@ -77,3 +77,7 @@ func (p *processor) AdminDomainBlockDelete(ctx context.Context, authed *oauth.Au
 func (p *processor) AdminMediaPrune(ctx context.Context, mediaRemoteCacheDays int) gtserror.WithCode {
 	return p.adminProcessor.MediaPrune(ctx, mediaRemoteCacheDays)
 }
+
+func (p *processor) AdminMediaRefetch(ctx context.Context, authed *oauth.Auth, domain string) gtserror.WithCode {
+	return p.adminProcessor.MediaRefetch(ctx, authed.Account, domain)
+}
--- a/internal/processing/admin/admin.go
+++ b/internal/processing/admin/admin.go
@ -30,6 +30,7 @@ import (
 	"github.com/superseriousbusiness/gotosocial/internal/media"
 	"github.com/superseriousbusiness/gotosocial/internal/messages"
 	"github.com/superseriousbusiness/gotosocial/internal/storage"
+	"github.com/superseriousbusiness/gotosocial/internal/transport"
 	"github.com/superseriousbusiness/gotosocial/internal/typeutils"
 )

@ -48,23 +49,26 @@ type Processor interface {
 	EmojiUpdate(ctx context.Context, id string, form *apimodel.EmojiUpdateRequest) (*apimodel.AdminEmoji, gtserror.WithCode)
 	EmojiCategoriesGet(ctx context.Context) ([]*apimodel.EmojiCategory, gtserror.WithCode)
 	MediaPrune(ctx context.Context, mediaRemoteCacheDays int) gtserror.WithCode
+	MediaRefetch(ctx context.Context, requestingAccount *gtsmodel.Account, domain string) gtserror.WithCode
 }

 type processor struct {
-	tc           typeutils.TypeConverter
-	mediaManager media.Manager
-	storage      *storage.Driver
-	clientWorker *concurrency.WorkerPool[messages.FromClientAPI]
-	db           db.DB
+	tc                  typeutils.TypeConverter
+	mediaManager        media.Manager
+	transportController transport.Controller
+	storage             *storage.Driver
+	clientWorker        *concurrency.WorkerPool[messages.FromClientAPI]
+	db                  db.DB
 }

 // New returns a new admin processor.
-func New(db db.DB, tc typeutils.TypeConverter, mediaManager media.Manager, storage *storage.Driver, clientWorker *concurrency.WorkerPool[messages.FromClientAPI]) Processor {
+func New(db db.DB, tc typeutils.TypeConverter, mediaManager media.Manager, transportController transport.Controller, storage *storage.Driver, clientWorker *concurrency.WorkerPool[messages.FromClientAPI]) Processor {
 	return &processor{
-		tc:           tc,
-		mediaManager: mediaManager,
-		storage:      storage,
-		clientWorker: clientWorker,
-		db:           db,
+		tc:                  tc,
+		mediaManager:        mediaManager,
+		transportController: transportController,
+		storage:             storage,
+		clientWorker:        clientWorker,
+		db:                  db,
 	}
 }
--- a/internal/processing/admin/getemojis.go
+++ b/internal/processing/admin/getemojis.go
@ -88,14 +88,10 @@ func (p *processor) EmojisGet(ctx context.Context, account *gtsmodel.Account, us
 		Items:            items,
 		Path:             "api/v1/admin/custom_emojis",
 		NextMaxIDKey:     "max_shortcode_domain",
-		NextMaxIDValue:   shortcodeDomain(emojis[count-1]),
+		NextMaxIDValue:   util.ShortcodeDomain(emojis[count-1]),
 		PrevMinIDKey:     "min_shortcode_domain",
-		PrevMinIDValue:   shortcodeDomain(emojis[0]),
+		PrevMinIDValue:   util.ShortcodeDomain(emojis[0]),
 		Limit:            limit,
 		ExtraQueryParams: []string{filterBuilder.String()},
 	})
 }
-
-func shortcodeDomain(emoji *gtsmodel.Emoji) string {
-	return emoji.Shortcode + "@" + emoji.Domain
-}
--- a/internal/processing/admin/mediarefetch.go
+++ b/internal/processing/admin/mediarefetch.go
@ -0,0 +1,48 @@
+/*
+   GoToSocial
+   Copyright (C) 2021-2022 GoToSocial Authors admin@gotosocial.org
+
+   This program is free software: you can redistribute it and/or modify
+   it under the terms of the GNU Affero General Public License as published by
+   the Free Software Foundation, either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU Affero General Public License for more details.
+
+   You should have received a copy of the GNU Affero General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+package admin
+
+import (
+	"context"
+	"fmt"
+
+	"github.com/superseriousbusiness/gotosocial/internal/gtserror"
+	"github.com/superseriousbusiness/gotosocial/internal/gtsmodel"
+	"github.com/superseriousbusiness/gotosocial/internal/log"
+)
+
+func (p *processor) MediaRefetch(ctx context.Context, requestingAccount *gtsmodel.Account, domain string) gtserror.WithCode {
+	transport, err := p.transportController.NewTransportForUsername(ctx, requestingAccount.Username)
+	if err != nil {
+		err = fmt.Errorf("error getting transport for user %s during media refetch request: %w", requestingAccount.Username, err)
+		return gtserror.NewErrorInternalError(err)
+	}
+
+	go func() {
+		log.Info("starting emoji refetch")
+		refetched, err := p.mediaManager.RefetchEmojis(context.Background(), domain, transport.DereferenceMedia)
+		if err != nil {
+			log.Errorf("error refetching emojis: %s", err)
+		} else {
+			log.Infof("refetched %d emojis from remote", refetched)
+		}
+	}()
+
+	return nil
+}
--- a/internal/processing/processor.go
+++ b/internal/processing/processor.go
@ -136,6 +136,8 @@ type Processor interface {
 	AdminDomainBlockDelete(ctx context.Context, authed *oauth.Auth, id string) (*apimodel.DomainBlock, gtserror.WithCode)
 	// AdminMediaRemotePrune triggers a prune of remote media according to the given number of mediaRemoteCacheDays
 	AdminMediaPrune(ctx context.Context, mediaRemoteCacheDays int) gtserror.WithCode
+	// AdminMediaRefetch triggers a refetch of remote media for the given domain (or all if domain is empty).
+	AdminMediaRefetch(ctx context.Context, authed *oauth.Auth, domain string) gtserror.WithCode

 	// AppCreate processes the creation of a new API application
 	AppCreate(ctx context.Context, authed *oauth.Auth, form *apimodel.ApplicationCreateRequest) (*apimodel.Application, gtserror.WithCode)
@ -318,7 +320,7 @@ func NewProcessor(
 	statusProcessor := status.New(db, tc, clientWorker, parseMentionFunc)
 	streamingProcessor := streaming.New(db, oauthServer)
 	accountProcessor := account.New(db, tc, mediaManager, oauthServer, clientWorker, federator, parseMentionFunc)
-	adminProcessor := admin.New(db, tc, mediaManager, storage, clientWorker)
+	adminProcessor := admin.New(db, tc, mediaManager, federator.TransportController(), storage, clientWorker)
 	mediaProcessor := mediaProcessor.New(db, tc, mediaManager, federator.TransportController(), storage)
 	userProcessor := user.New(db, emailSender)
 	federationProcessor := federationProcessor.New(db, tc, federator)
--- a/internal/util/emoji.go
+++ b/internal/util/emoji.go
@ -0,0 +1,26 @@
+/*
+   GoToSocial
+   Copyright (C) 2021-2022 GoToSocial Authors admin@gotosocial.org
+
+   This program is free software: you can redistribute it and/or modify
+   it under the terms of the GNU Affero General Public License as published by
+   the Free Software Foundation, either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU Affero General Public License for more details.
+
+   You should have received a copy of the GNU Affero General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+package util
+
+import "github.com/superseriousbusiness/gotosocial/internal/gtsmodel"
+
+// ShortcodeDomain returns the [shortcode]@[domain] for the given emoji.
+func ShortcodeDomain(emoji *gtsmodel.Emoji) string {
+	return emoji.Shortcode + "@" + emoji.Domain
+}