Add GL_GROUP group avatars (auto-update)

Add GL_GROUP group avatars (auto-update). Every 7 days, we look if the avatar on GitLab has changed (we already do this for GitHub).

Part of https://gitlab.com/gitlab-org/gitter/webapp/issues/2393

Dev notes

My quick link (need to clear cache): http://localhost:5000/api/private/avatars/group/i/5df865d638da38f1fa1ecd9f

db.groups.insert({
        "name" : "_test-gitlab-group-test-community",
        "uri" : "_test-gitlab-group-test-community",
        "lcUri" : "_test-gitlab-group-test-community",
        "lcHomeUri" : "_test-gitlab-group-test-community/home",
        "homeUri" : "_test-gitlab-group-test-community/home",
        "sd" : {
                "externalId" : "3281315",
                "linkPath" : "gitter-integration-tests-group",
                "public" : true,
                "admins" : "GL_GROUP_MAINTAINER",
                "members" : "PUBLIC",
                "type" : "GL_GROUP"
        },
});

db.groups.update({ "lcUri" : "_test-gitlab-group-test-community" }, {
        $unset: {
                "avatarUrl" : 1,
                "avatarCheckedDate" :1,
                "avatarVersion" : 1
        }
});

GitHub Avatars

GitHub has a nice predictable constructable URL: https://avatars.githubusercontent.com/<username-or-group>?s=<size>

GitLab Avatars

Avatars from GitLab don't have a predictable URL.

If there is a custom upload, then the filename is whatever you uploaded:

• https://assets.gitlab-static.net/uploads/-/system/project/avatar/3601513/gitter_logo.png?width=15
• https://assets.gitlab-static.net/uploads/-/system/group/avatar/9970/logo-extra-whitespace.png?width=64

This MR isn't supporting user namespaces. But users use Gravatar unless you upload something,

• https://secure.gravatar.com/avatar/4d634a2b818e2265fa2924b5f4c2da71?s=180&d=identicon
• https://assets.gitlab-static.net/uploads/-/system/user/avatar/1577466/avatar.png?width=90

TODO

• Since GitLab doesn't have a predictable avatar URL we can't construct the URL on the fly. We need to find a place to store the avatarURL after we fetch it. We can use group.avatarUrl but need to make sure not to overwrite someones separate custom upload
  • Currently, this is protected because we have a early return if a custom avatar(group.avatarUrl) is set
• Write migration for groups with custom avata set(group.avatarUrl) to group.avatarCheckedDate = new Date(3000)
  • https://gitlab.com/gitlab-org/gitter/webapp/merge_requests/1692#note_261452703

Testing strategy

1. Insert a new GitLab Gitter group into Mongo

   db.groups.insert({
           "name" : "_test-gitlab-group-test-community",
           "uri" : "_test-gitlab-group-test-community",
           "lcUri" : "_test-gitlab-group-test-community",
           "lcHomeUri" : "_test-gitlab-group-test-community/home",
           "homeUri" : "_test-gitlab-group-test-community/home",
           "sd" : {
                   "externalId" : "3281315",
                   "linkPath" : "gitter-integration-tests-group",
                   "public" : true,
                   "admins" : "GL_GROUP_MAINTAINER",
                   "members" : "PUBLIC",
                   "type" : "GL_GROUP"
           },
   });

2. Get the group ID: db.groups.findOne({ "lcUri" : "_test-gitlab-group-test-community" })
3. Visit http://localhost:5000/api/private/avatars/group/i/<groupId>, it will go to https://avatars.githubusercontent.com/undefined?s=128 but now the avatar is updated
4. Empty cache and hard reload
5. Visit http://localhost:5000/api/private/avatars/group/i/<groupId> again, it should go to https://assets.gitlab-static.net/uploads/-/system/group/avatar/3281315/test-avatar1.png?width=128?v=1

You can reset and test again by clearing out the avatar properties:

db.groups.update({ "lcUri" : "_test-gitlab-group-test-community" }, {
        $unset: {
                "avatarUrl" : 1,
                "avatarCheckedDate" :1,
                "avatarVersion" : 1
        }
});