sync profile images (#17375)

support for synchronizing user's profile image for shared channels.

Makefile

@@ -374,7 +374,7 @@ test-server-race: test-server-pre
   endif
 
 test-server: test-server-pre
-	./scripts/test.sh "$(GO)" "$(GOFLAGS)" "$(ALL_PACKAGES)" "$(TESTS)" "$(TESTFLAGS)" "$(GOBIN)" "20m" "count"
+	./scripts/test.sh "$(GO)" "$(GOFLAGS)" "$(ALL_PACKAGES)" "$(TESTS)" "$(TESTFLAGS)" "$(GOBIN)" "45m" "count"
   ifneq ($(IS_CI),true)
     ifneq ($(MM_NO_DOCKER),true)
       ifneq ($(TEMP_DOCKER_SERVICES),)

api4/remote_cluster.go

@@ -5,6 +5,8 @@ package api4
 
 import (
 	"encoding/json"
+	"io"
+	"io/ioutil"
 	"net/http"
 	"time"
 
@@ -18,6 +20,7 @@ func (api *API) InitRemoteCluster() {
 	api.BaseRoutes.RemoteCluster.Handle("/msg", api.RemoteClusterTokenRequired(remoteClusterAcceptMessage)).Methods("POST")
 	api.BaseRoutes.RemoteCluster.Handle("/confirm_invite", api.RemoteClusterTokenRequired(remoteClusterConfirmInvite)).Methods("POST")
 	api.BaseRoutes.RemoteCluster.Handle("/upload/{upload_id:[A-Za-z0-9]+}", api.RemoteClusterTokenRequired(uploadRemoteData)).Methods("POST")
+	api.BaseRoutes.RemoteCluster.Handle("/{user_id:[A-Za-z0-9]+}/image", api.RemoteClusterTokenRequired(remoteSetProfileImage)).Methods("POST")
 }
 
 func remoteClusterPing(c *Context, w http.ResponseWriter, r *http.Request) {
@@ -212,3 +215,63 @@ func uploadRemoteData(c *Context, w http.ResponseWriter, r *http.Request) {
 
 	w.Write([]byte(info.ToJson()))
 }
+
+func remoteSetProfileImage(c *Context, w http.ResponseWriter, r *http.Request) {
+	defer io.Copy(ioutil.Discard, r.Body)
+
+	c.RequireUserId()
+	if c.Err != nil {
+		return
+	}
+
+	if *c.App.Config().FileSettings.DriverName == "" {
+		c.Err = model.NewAppError("remoteUploadProfileImage", "api.user.upload_profile_user.storage.app_error", nil, "", http.StatusNotImplemented)
+		return
+	}
+
+	if r.ContentLength > *c.App.Config().FileSettings.MaxFileSize {
+		c.Err = model.NewAppError("remoteUploadProfileImage", "api.user.upload_profile_user.too_large.app_error", nil, "", http.StatusRequestEntityTooLarge)
+		return
+	}
+
+	if err := r.ParseMultipartForm(*c.App.Config().FileSettings.MaxFileSize); err != nil {
+		c.Err = model.NewAppError("remoteUploadProfileImage", "api.user.upload_profile_user.parse.app_error", nil, err.Error(), http.StatusInternalServerError)
+		return
+	}
+
+	m := r.MultipartForm
+	imageArray, ok := m.File["image"]
+	if !ok {
+		c.Err = model.NewAppError("remoteUploadProfileImage", "api.user.upload_profile_user.no_file.app_error", nil, "", http.StatusBadRequest)
+		return
+	}
+
+	if len(imageArray) == 0 {
+		c.Err = model.NewAppError("remoteUploadProfileImage", "api.user.upload_profile_user.array.app_error", nil, "", http.StatusBadRequest)
+		return
+	}
+
+	auditRec := c.MakeAuditRecord("remoteUploadProfileImage", audit.Fail)
+	defer c.LogAuditRec(auditRec)
+	if imageArray[0] != nil {
+		auditRec.AddMeta("filename", imageArray[0].Filename)
+	}
+
+	user, err := c.App.GetUser(c.Params.UserId)
+	if err != nil || !user.IsRemote() {
+		c.SetInvalidUrlParam("user_id")
+		return
+	}
+	auditRec.AddMeta("user", user)
+
+	imageData := imageArray[0]
+	if err := c.App.SetProfileImage(c.Params.UserId, imageData); err != nil {
+		c.Err = err
+		return
+	}
+
+	auditRec.Success()
+	c.LogAudit("")
+
+	ReturnStatusOK(w)
+}

model/user.go

@@ -752,6 +752,14 @@ func (u *User) IsRemote() bool {
 	return u.RemoteId != nil && *u.RemoteId != ""
 }
 
+// GetRemoteID returns the remote id for this user or "" if not a remote user.
+func (u *User) GetRemoteID() string {
+	if u.RemoteId != nil {
+		return *u.RemoteId
+	}
+	return ""
+}
+
 // GetProp fetches a prop value by name.
 func (u *User) GetProp(name string) (string, bool) {
 	val, ok := u.Props[name]

services/remotecluster/mocks_test.go

@@ -4,6 +4,7 @@
 package remotecluster
 
 import (
+	"context"
 	"fmt"
 	"strings"
 	"sync"
@@ -22,6 +23,7 @@ import (
 type mockServer struct {
 	remotes []*model.RemoteCluster
 	logger  *mockLogger
+	user    *model.User
 }
 
 func newMockServer(t *testing.T, remotes []*model.RemoteCluster) *mockServer {
@@ -31,6 +33,10 @@ func newMockServer(t *testing.T, remotes []*model.RemoteCluster) *mockServer {
 	}
 }
 
+func (ms *mockServer) SetUser(user *model.User) {
+	ms.user = user
+}
+
 func (ms *mockServer) Config() *model.Config                                  { return nil }
 func (ms *mockServer) GetMetrics() einterfaces.MetricsInterface               { return nil }
 func (ms *mockServer) IsLeader() bool                                         { return true }
@@ -40,16 +46,21 @@ func (ms *mockServer) GetLogger() mlog.LoggerIFace {
 	return ms.logger
 }
 func (ms *mockServer) GetStore() store.Store {
-	anyFilter := mock.MatchedBy(func(filter model.RemoteClusterQueryFilter) bool {
+	anyQueryFilter := mock.MatchedBy(func(filter model.RemoteClusterQueryFilter) bool {
 		return true
 	})
+	anyUserId := mock.AnythingOfType("string")
 
 	remoteClusterStoreMock := &mocks.RemoteClusterStore{}
 	remoteClusterStoreMock.On("GetByTopic", "share").Return(ms.remotes, nil)
-	remoteClusterStoreMock.On("GetAll", anyFilter).Return(ms.remotes, nil)
+	remoteClusterStoreMock.On("GetAll", anyQueryFilter).Return(ms.remotes, nil)
+
+	userStoreMock := &mocks.UserStore{}
+	userStoreMock.On("Get", context.Background(), anyUserId).Return(ms.user, nil)
 
 	storeMock := &mocks.Store{}
 	storeMock.On("RemoteCluster").Return(remoteClusterStoreMock)
+	storeMock.On("User").Return(userStoreMock)
 	return storeMock
 }
 func (ms *mockServer) Shutdown() { ms.logger.Shutdown() }

services/remotecluster/send.go

@@ -48,6 +48,8 @@ func (rcs *Service) sendLoop(idx int, done chan struct{}) {
 				rcs.sendMsg(task)
 			case sendFileTask:
 				rcs.sendFile(task)
+			case sendProfileImageTask:
+				rcs.sendProfileImage(task)
 			}
 		case <-done:
 			return

services/remotecluster/sendfile.go

@@ -35,9 +35,9 @@ type ReaderProvider interface {
 // SendFile asynchronously sends a file to a remote cluster.
 //
 // `ctx` determines behaviour when the outbound queue is full. A timeout or deadline context will return a
-// BufferFullError if the file cannot be enqueued before the timeout. A background context will block indefinitely.
+// BufferFullError if the task cannot be enqueued before the timeout. A background context will block indefinitely.
 //
-// Nil or error return indicates success or failure of file enqueue only.
+// Nil or error return indicates success or failure of task enqueue only.
 //
 // An optional callback can be provided that receives the response from the remote cluster. The `err` provided to the
 // callback is regarding file delivery only. The `resp` contains the decoded bytes returned from the remote.
@@ -55,17 +55,6 @@ func (rcs *Service) SendFile(ctx context.Context, us *model.UploadSession, fi *m
 
 // sendFile is called when a sendFileTask is popped from the send channel.
 func (rcs *Service) sendFile(task sendFileTask) {
-	// Ensure a panic from the callback does not exit the goroutine.
-	defer func() {
-		if r := recover(); r != nil {
-			rcs.server.GetLogger().Log(mlog.LvlRemoteClusterServiceError, "Remote Cluster sendFile panic",
-				mlog.String("remote", task.rc.DisplayName),
-				mlog.String("uploadId", task.us.Id),
-				mlog.Any("panic", r),
-			)
-		}
-	}()
-
 	fi, err := rcs.sendFileToRemote(SendTimeout, task)
 	var response Response
 

services/remotecluster/sendmsg.go

@@ -82,13 +82,6 @@ func (rcs *Service) sendMsg(task sendMsgTask) {
 
 	// Ensure a panic from the callback does not exit the pool goroutine.
 	defer func() {
-		if r := recover(); r != nil {
-			rcs.server.GetLogger().Log(mlog.LvlRemoteClusterServiceError, "Remote Cluster sendMsg panic",
-				mlog.String("remote", task.rc.DisplayName),
-				mlog.String("msgId", task.msg.Id), mlog.Any("panic", r),
-			)
-		}
-
 		if errResp != nil {
 			response.Err = errResp.Error()
 		}

services/remotecluster/sendprofileImage.go

@@ -0,0 +1,146 @@
+// Copyright (c) 2015-present Mattermost, Inc. All Rights Reserved.
+// See LICENSE.txt for license information.
+
+package remotecluster
+
+import (
+	"bytes"
+	"context"
+	"fmt"
+	"io"
+	"io/ioutil"
+	"mime/multipart"
+	"net/http"
+	"net/url"
+	"path"
+	"time"
+
+	"github.com/mattermost/mattermost-server/v5/model"
+	"github.com/mattermost/mattermost-server/v5/shared/mlog"
+)
+
+type SendProfileImageResultFunc func(userId string, rc *model.RemoteCluster, resp *Response, err error)
+
+type sendProfileImageTask struct {
+	rc       *model.RemoteCluster
+	userID   string
+	provider ProfileImageProvider
+	f        SendProfileImageResultFunc
+}
+
+type ProfileImageProvider interface {
+	GetProfileImage(user *model.User) ([]byte, bool, *model.AppError)
+}
+
+// SendProfileImage asynchronously sends a user's profile image to a remote cluster.
+//
+// `ctx` determines behaviour when the outbound queue is full. A timeout or deadline context will return a
+// BufferFullError if the task cannot be enqueued before the timeout. A background context will block indefinitely.
+//
+// Nil or error return indicates success or failure of task enqueue only.
+//
+// An optional callback can be provided that receives the response from the remote cluster. The `err` provided to the
+// callback is regarding image delivery only. The `resp` contains the decoded bytes returned from the remote.
+// If a callback is provided it should return quickly.
+func (rcs *Service) SendProfileImage(ctx context.Context, userID string, rc *model.RemoteCluster, provider ProfileImageProvider, f SendProfileImageResultFunc) error {
+	task := sendProfileImageTask{
+		rc:       rc,
+		userID:   userID,
+		provider: provider,
+		f:        f,
+	}
+	return rcs.enqueueTask(ctx, rc.RemoteId, task)
+}
+
+// sendProfileImage is called when a sendProfileImageTask is popped from the send channel.
+func (rcs *Service) sendProfileImage(task sendProfileImageTask) {
+	err := rcs.sendProfileImageToRemote(SendTimeout, task)
+	var response Response
+
+	if err != nil {
+		rcs.server.GetLogger().Log(mlog.LvlRemoteClusterServiceError, "Remote Cluster send profile image failed",
+			mlog.String("remote", task.rc.DisplayName),
+			mlog.String("UserId", task.userID),
+			mlog.Err(err),
+		)
+		response.Status = ResponseStatusFail
+		response.Err = err.Error()
+	} else {
+		rcs.server.GetLogger().Log(mlog.LvlRemoteClusterServiceDebug, "Remote Cluster profile image sent successfully",
+			mlog.String("remote", task.rc.DisplayName),
+			mlog.String("UserId", task.userID),
+		)
+		response.Status = ResponseStatusOK
+	}
+
+	// If callback provided then call it with the results.
+	if task.f != nil {
+		task.f(task.userID, task.rc, &response, err)
+	}
+}
+
+func (rcs *Service) sendProfileImageToRemote(timeout time.Duration, task sendProfileImageTask) error {
+	rcs.server.GetLogger().Log(mlog.LvlRemoteClusterServiceDebug, "sending profile image to remote...",
+		mlog.String("remote", task.rc.DisplayName),
+		mlog.String("UserId", task.userID),
+	)
+
+	user, err := rcs.server.GetStore().User().Get(context.Background(), task.userID)
+	if err != nil {
+		return fmt.Errorf("error fetching user while sending profile image to remote %s: %w", task.rc.RemoteId, err)
+	}
+
+	img, _, appErr := task.provider.GetProfileImage(user) // get Reader for the file
+	if appErr != nil {
+		return fmt.Errorf("error fetching profile image for user (%s) while sending to remote %s: %w", task.userID, task.rc.RemoteId, appErr)
+	}
+
+	u, err := url.Parse(task.rc.SiteURL)
+	if err != nil {
+		return fmt.Errorf("invalid siteURL while sending file to remote %s: %w", task.rc.RemoteId, err)
+	}
+	u.Path = path.Join(u.Path, model.API_URL_SUFFIX, "remotecluster", task.userID, "image")
+
+	body := &bytes.Buffer{}
+	writer := multipart.NewWriter(body)
+
+	part, err := writer.CreateFormFile("image", "profile.png")
+	if err != nil {
+		return err
+	}
+
+	if _, err = io.Copy(part, bytes.NewBuffer(img)); err != nil {
+		return err
+	}
+
+	if err = writer.Close(); err != nil {
+		return err
+	}
+
+	req, err := http.NewRequest("POST", u.String(), body)
+	if err != nil {
+		return err
+	}
+	req.Header.Set("Content-Type", writer.FormDataContentType())
+	req.Header.Set(model.HEADER_REMOTECLUSTER_ID, task.rc.RemoteId)
+	req.Header.Set(model.HEADER_REMOTECLUSTER_TOKEN, task.rc.RemoteToken)
+
+	ctx, cancel := context.WithTimeout(context.Background(), timeout)
+	defer cancel()
+
+	resp, err := rcs.httpClient.Do(req.WithContext(ctx))
+	if err != nil {
+		return err
+	}
+	defer resp.Body.Close()
+
+	_, err = ioutil.ReadAll(resp.Body)
+	if err != nil {
+		return err
+	}
+
+	if resp.StatusCode != http.StatusOK {
+		return fmt.Errorf("unexpected response: %d - %s", resp.StatusCode, resp.Status)
+	}
+	return nil
+}

services/remotecluster/sendprofileImage_test.go

@@ -0,0 +1,187 @@
+// Copyright (c) 2015-present Mattermost, Inc. All Rights Reserved.
+// See LICENSE.txt for license information.
+
+package remotecluster
+
+import (
+	"bytes"
+	"image"
+	"image/color"
+	"image/png"
+	"io"
+	"io/ioutil"
+	"net/http"
+	"net/http/httptest"
+	"sync"
+	"testing"
+	"time"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+
+	"github.com/mattermost/mattermost-server/v5/model"
+)
+
+const (
+	imageWidth  = 128
+	imageHeight = 128
+)
+
+func TestService_sendProfileImageToRemote(t *testing.T) {
+	hadPing := disablePing
+	disablePing = true
+	defer func() { disablePing = hadPing }()
+
+	shouldError := &flag{}
+
+	ts := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		defer io.Copy(ioutil.Discard, r.Body)
+
+		if shouldError.get() {
+			w.WriteHeader(http.StatusInternalServerError)
+			resp := make(map[string]string)
+			resp[model.STATUS] = model.STATUS_FAIL
+			w.Write([]byte(model.MapToJson(resp)))
+			return
+		}
+
+		status := model.STATUS_OK
+		defer func(s *string) {
+			if *s != model.STATUS_OK {
+				w.WriteHeader(http.StatusInternalServerError)
+			}
+			resp := make(map[string]string)
+			resp[model.STATUS] = *s
+			w.Write([]byte(model.MapToJson(resp)))
+		}(&status)
+
+		if err := r.ParseMultipartForm(1024 * 1024); err != nil {
+			status = model.STATUS_FAIL
+			assert.Fail(t, "connect parse multipart form", err)
+			return
+		}
+		m := r.MultipartForm
+		if m == nil {
+			status = model.STATUS_FAIL
+			assert.Fail(t, "multipart form missing")
+			return
+		}
+
+		imageArray, ok := m.File["image"]
+		if !ok || len(imageArray) != 1 {
+			status = model.STATUS_FAIL
+			assert.Fail(t, "image missing")
+			return
+		}
+
+		imageData := imageArray[0]
+		file, err := imageData.Open()
+		if err != nil {
+			status = model.STATUS_FAIL
+			assert.Fail(t, "cannot open multipart form file")
+			return
+		}
+		defer file.Close()
+
+		img, err := png.Decode(file)
+		if err != nil || imageWidth != img.Bounds().Max.X || imageHeight != img.Bounds().Max.Y {
+			status = model.STATUS_FAIL
+			assert.Fail(t, "cannot decode png", err)
+			return
+		}
+	}))
+	defer ts.Close()
+
+	rc := makeRemoteCluster("remote_test_profile_image", ts.URL, TestTopics)
+
+	user := &model.User{
+		Id:       model.NewId(),
+		RemoteId: model.NewString(rc.RemoteId),
+	}
+
+	provider := testImageProvider{}
+
+	mockServer := newMockServer(t, makeRemoteClusters(NumRemotes, ts.URL))
+	mockServer.SetUser(user)
+	service, err := NewRemoteClusterService(mockServer)
+	require.NoError(t, err)
+
+	err = service.Start()
+	require.NoError(t, err)
+	defer service.Shutdown()
+
+	t.Run("Server response 200", func(t *testing.T) {
+		shouldError.set(false)
+
+		resultFunc := func(userId string, rc *model.RemoteCluster, resp *Response, err error) {
+			assert.Equal(t, user.Id, userId, "user ids should match")
+			assert.NoError(t, err)
+			assert.True(t, resp.IsSuccess())
+		}
+
+		task := sendProfileImageTask{
+			rc:       rc,
+			userID:   user.Id,
+			provider: provider,
+			f:        resultFunc,
+		}
+
+		err := service.sendProfileImageToRemote(time.Second*15, task)
+		assert.NoError(t, err, "request should not error")
+	})
+
+	t.Run("Server response 500", func(t *testing.T) {
+		shouldError.set(true)
+
+		resultFunc := func(userId string, rc *model.RemoteCluster, resp *Response, err error) {
+			assert.Equal(t, user.Id, userId, "user ids should match")
+			assert.False(t, resp.IsSuccess())
+		}
+
+		task := sendProfileImageTask{
+			rc:       rc,
+			userID:   user.Id,
+			provider: provider,
+			f:        resultFunc,
+		}
+
+		err := service.sendProfileImageToRemote(time.Second*15, task)
+		assert.Error(t, err, "request should error")
+	})
+}
+
+type testImageProvider struct {
+}
+
+func (tip testImageProvider) GetProfileImage(user *model.User) ([]byte, bool, *model.AppError) {
+	img := image.NewRGBA(image.Rectangle{image.Point{0, 0}, image.Point{imageWidth, imageHeight}})
+	red := color.RGBA{255, 50, 50, 0xff}
+
+	for x := 0; x < imageWidth; x++ {
+		for y := 0; y < imageHeight; y++ {
+			img.Set(x, y, red)
+		}
+	}
+
+	buf := &bytes.Buffer{}
+	png.Encode(buf, img)
+
+	return buf.Bytes(), true, nil
+}
+
+type flag struct {
+	mux sync.RWMutex
+	b   bool
+}
+
+func (f *flag) get() bool {
+	f.mux.RLock()
+	defer f.mux.RUnlock()
+	return f.b
+}
+
+func (f *flag) set(b bool) {
+	f.mux.Lock()
+	defer f.mux.Unlock()
+	f.b = b
+}

services/remotecluster/service.go

@@ -63,6 +63,7 @@ type RemoteClusterServiceIFace interface {
 	RemoveConnectionStateListener(listenerId string)
 	SendMsg(ctx context.Context, msg model.RemoteClusterMsg, rc *model.RemoteCluster, f SendMsgResultFunc) error
 	SendFile(ctx context.Context, us *model.UploadSession, fi *model.FileInfo, rc *model.RemoteCluster, rp ReaderProvider, f SendFileResultFunc) error
+	SendProfileImage(ctx context.Context, userID string, rc *model.RemoteCluster, provider ProfileImageProvider, f SendProfileImageResultFunc) error
 	AcceptInvitation(invite *model.RemoteClusterInvite, name string, displayName string, creatorId string, teamId string, siteURL string) (*model.RemoteCluster, error)
 	ReceiveIncomingMsg(rc *model.RemoteCluster, msg model.RemoteClusterMsg) Response
 }

services/sharedchannel/mock_AppIface_test.go

@@ -230,6 +230,38 @@ func (_m *MockAppIface) GetOrCreateDirectChannel(userId string, otherUserId stri
 	return r0, r1
 }
 
+// GetProfileImage provides a mock function with given fields: user
+func (_m *MockAppIface) GetProfileImage(user *model.User) ([]byte, bool, *model.AppError) {
+	ret := _m.Called(user)
+
+	var r0 []byte
+	if rf, ok := ret.Get(0).(func(*model.User) []byte); ok {
+		r0 = rf(user)
+	} else {
+		if ret.Get(0) != nil {
+			r0 = ret.Get(0).([]byte)
+		}
+	}
+
+	var r1 bool
+	if rf, ok := ret.Get(1).(func(*model.User) bool); ok {
+		r1 = rf(user)
+	} else {
+		r1 = ret.Get(1).(bool)
+	}
+
+	var r2 *model.AppError
+	if rf, ok := ret.Get(2).(func(*model.User) *model.AppError); ok {
+		r2 = rf(user)
+	} else {
+		if ret.Get(2) != nil {
+			r2 = ret.Get(2).(*model.AppError)
+		}
+	}
+
+	return r0, r1, r2
+}
+
 // InvalidateCacheForUser provides a mock function with given fields: userID
 func (_m *MockAppIface) InvalidateCacheForUser(userID string) {
 	_m.Called(userID)

services/sharedchannel/msg.go

@@ -7,8 +7,10 @@ import (
 	"context"
 	"encoding/json"
 	"strings"
+	"time"
 
 	"github.com/mattermost/mattermost-server/v5/model"
+	"github.com/mattermost/mattermost-server/v5/services/remotecluster"
 	"github.com/mattermost/mattermost-server/v5/shared/mlog"
 )
 
@@ -177,26 +179,35 @@ func (scs *Service) usersForPost(post *model.Post, reactions []*model.Reaction,
 
 	for _, id := range userIds {
 		user, err := scs.server.GetStore().User().Get(context.Background(), id)
-		if err == nil {
-			if sync, err2 := scs.shouldUserSync(user, channelID, rc); err2 != nil {
-				scs.server.GetLogger().Log(mlog.LvlSharedChannelServiceError, "Could not find user for post",
-					mlog.String("user_id", id),
-					mlog.Err(err2),
-				)
-				continue
-			} else if sync {
-				users = append(users, sanitizeUserForSync(user))
-			}
-			// if this was a mention then put the real username in place of the username+remotename, but only
-			// when sending to the remote that the user belongs to.
-			if user.RemoteId != nil && *user.RemoteId == rc.RemoteId {
-				fixMention(post, mentionMap, user)
-			}
-		} else {
+		if err != nil {
 			scs.server.GetLogger().Log(mlog.LvlSharedChannelServiceError, "Error checking if user should sync",
 				mlog.String("user_id", id),
 				mlog.Err(err),
 			)
+			continue
+		}
+
+		sync, syncImage, err2 := scs.shouldUserSync(user, channelID, rc)
+		if err2 != nil {
+			scs.server.GetLogger().Log(mlog.LvlSharedChannelServiceError, "Could not find user for post",
+				mlog.String("user_id", id),
+				mlog.Err(err2),
+			)
+			continue
+		}
+
+		if sync {
+			users = append(users, sanitizeUserForSync(user))
+		}
+
+		if syncImage {
+			scs.syncProfileImage(user, channelID, rc)
+		}
+
+		// if this was a mention then put the real username in place of the username+remotename, but only
+		// when sending to the remote that the user belongs to.
+		if user.RemoteId != nil && *user.RemoteId == rc.RemoteId {
+			fixMention(post, mentionMap, user)
 		}
 	}
 	return users
@@ -240,16 +251,16 @@ func sanitizeUserForSync(user *model.User) *model.User {
 // shouldUserSync determines if a user needs to be synchronized.
 // User should be synchronized if it has no entry in the SharedChannelUsers table for the specified channel,
 // or there is an entry but the LastSyncAt is less than user.UpdateAt
-func (scs *Service) shouldUserSync(user *model.User, channelID string, rc *model.RemoteCluster) (bool, error) {
+func (scs *Service) shouldUserSync(user *model.User, channelID string, rc *model.RemoteCluster) (sync bool, syncImage bool, err error) {
 	// don't sync users with the remote they originated from.
 	if user.RemoteId != nil && *user.RemoteId == rc.RemoteId {
-		return false, nil
+		return false, false, nil
 	}
 
 	scu, err := scs.server.GetStore().SharedChannel().GetUser(user.Id, channelID, rc.RemoteId)
 	if err != nil {
 		if _, ok := err.(errNotFound); !ok {
-			return false, err
+			return false, false, err
 		}
 
 		// user not in the SharedChannelUsers table, so we must add them.
@@ -266,8 +277,52 @@ func (scs *Service) shouldUserSync(user *model.User, channelID string, rc *model
 				mlog.Err(err),
 			)
 		}
-	} else if scu.LastSyncAt >= user.UpdateAt {
-		return false, nil
+		return true, true, nil
 	}
-	return true, nil
+
+	return user.UpdateAt > scu.LastSyncAt, user.LastPictureUpdate > scu.LastSyncAt, nil
+}
+
+func (scs *Service) syncProfileImage(user *model.User, channelID string, rc *model.RemoteCluster) {
+	rcs := scs.server.GetRemoteClusterService()
+	if rcs == nil {
+		return
+	}
+
+	ctx, cancel := context.WithTimeout(context.Background(), time.Second*5)
+	defer cancel()
+
+	rcs.SendProfileImage(ctx, user.Id, rc, scs.app, func(userId string, rc *model.RemoteCluster, resp *remotecluster.Response, err error) {
+		if resp.IsSuccess() {
+			scs.server.GetLogger().Log(mlog.LvlSharedChannelServiceDebug, "Users profile image synchronized",
+				mlog.String("remote_id", rc.RemoteId),
+				mlog.String("user_id", user.Id),
+			)
+
+			scu, err := scs.server.GetStore().SharedChannel().GetUser(user.Id, channelID, rc.RemoteId)
+			if err != nil {
+				scs.server.GetLogger().Log(mlog.LvlSharedChannelServiceError, "Error fetching shared channel user while updating users LastSyncTime after profile image update",
+					mlog.String("remote_id", rc.RemoteId),
+					mlog.String("user_id", user.Id),
+					mlog.String("channel_id", channelID),
+					mlog.Err(err),
+				)
+			}
+
+			if err = scs.server.GetStore().SharedChannel().UpdateUserLastSyncAt(scu.Id, model.GetMillis()); err != nil {
+				scs.server.GetLogger().Log(mlog.LvlSharedChannelServiceError, "Error updating users LastSyncTime after profile image update",
+					mlog.String("remote_id", rc.RemoteId),
+					mlog.String("user_id", user.Id),
+					mlog.Err(err),
+				)
+			}
+			return
+		}
+
+		scs.server.GetLogger().Log(mlog.LvlSharedChannelServiceError, "Error synchronizing users profile image",
+			mlog.String("remote_id", rc.RemoteId),
+			mlog.String("user_id", user.Id),
+			mlog.String("Err", resp.Err),
+		)
+	})
 }

services/sharedchannel/service.go

@@ -57,6 +57,7 @@ type AppIface interface {
 	CreateUploadSession(us *model.UploadSession) (*model.UploadSession, *model.AppError)
 	FileReader(path string) (filestore.ReadCloseSeeker, *model.AppError)
 	MentionsToTeamMembers(message, teamID string) model.UserMentionMap
+	GetProfileImage(user *model.User) ([]byte, bool, *model.AppError)
 	InvalidateCacheForUser(userID string)
 	NotifySharedChannelUserUpdate(user *model.User)
 }