Gravatar fallback for airgapped environments
Problem to solve
When using GitLab in an airgapped environment, we still try to fetch avatars from external services when there is no one locally available.
Further details
As they can't be fetched, the user ends up with a broken image.
We should ideally fallback to either a generic picture or a generic gravatar-like identicons / initial letters implementation. I understand it's possible to configure a custom gravatar provider, but this is not practical for most of our users (this is probably more used by open source projects hosting their own GitLab).
Proposal
Automatically generate identicons for each new user (we can do this asynchronously after the user is created and we can use this gem: https://github.com/chrisbranson/ruby_identicon). This should be configurable (enabled by default, if disabled fallback to generic empty picture).
Move gravatar configuration out of the YAML file, into to the database and make it Opt-in instead of Opt-out, so by default we provide identicons.
What does success look like, and how can we measure that?
A new GitLab installation should not require gravatar by default, and should provide nice, identifiable default avatars.