In many cases user avatar link should be an absolute URL with http host

integrations/user_avatar_test.go

@@ -73,7 +73,7 @@ func TestUserAvatar(t *testing.T) {
 
 		user2 = db.AssertExistsAndLoadBean(t, &models.User{ID: 2}).(*models.User) // owner of the repo3, is an org
 
-		req = NewRequest(t, "GET", user2.AvatarLink())
+		req = NewRequest(t, "GET", user2.AvatarLinkWithSize(0))
 		_ = session.MakeRequest(t, req, http.StatusOK)
 
 		// Can't test if the response matches because the image is re-generated on upload but checking that this at least doesn't give a 404 should be enough.

models/user_avatar.go

@@ -9,6 +9,7 @@ import (
 	"fmt"
 	"image/png"
 	"io"
+	"strings"
 
 	"code.gitea.io/gitea/models/avatars"
 	"code.gitea.io/gitea/models/db"
@@ -91,9 +92,13 @@ func (u *User) AvatarLinkWithSize(size int) string {
 	return avatars.GenerateEmailAvatarFastLink(u.AvatarEmail, size)
 }
 
-// AvatarLink returns a avatar link with default size
+// AvatarLink returns the full avatar link with http host
 func (u *User) AvatarLink() string {
-	return u.AvatarLinkWithSize(0)
+	link := u.AvatarLinkWithSize(0)
+	if !strings.HasPrefix(link, "//") && !strings.Contains(link, "://") {
+		return setting.AppURL + strings.TrimPrefix(link, setting.AppSubURL+"/")
+	}
+	return link
 }
 
 // UploadAvatar saves custom avatar for user.

modules/convert/user_test.go

@@ -21,6 +21,7 @@ func TestUser_ToUser(t *testing.T) {
 
 	apiUser := toUser(user1, true, true)
 	assert.True(t, apiUser.IsAdmin)
+	assert.Contains(t, apiUser.AvatarURL, "://")
 
 	user2 := db.AssertExistsAndLoadBean(t, &models.User{ID: 2, IsAdmin: false}).(*models.User)