Always set the config key with an empty list, even if a list isn't specified.
This means that the codepaths are the same for both the empty list and
for a missing key. Since the behaviour is the same for both cases this
makes the code somewhat easier to reason about.
This is so that a single MediaRepository can be shared across all
resources, rather than having a "copy" per resource.
In particular this allows us to guard against both the thumbnail and
download resource triggering a download of remote content at the same
time.
Add url_preview_ip_range_blacklist to let admins specify internal IP ranges that must not be spidered.
Add url_preview_url_blacklist to let admins specify URL patterns that must not be spidered.
Implement a custom SpiderEndpoint and associated support classes to implement url_preview_ip_range_blacklist
Add commentary and generally address PR feedback
Introduce a User object
I'm sick of passing around more and more things as tuple items around
the whole world, and needing to edit every call site every time there is
more information about a user. So pass them around together as an
object.
This object has incredibly poorly named fields because we have a
convention that `user` indicates a UserID object, and `user_id`
indicates a string. I tried to clean up the whole repo to fix this, but
gave up. So instead, I introduce a second convention. A user_object is a
User, and a user_id_object is a UserId. I may have cried a little bit.
This tracks data about the entity which made the request. This is
instead of passing around a tuple, which requires call-site
modifications every time a new piece of optional context is passed
around.
I tried to introduce a User object. I gave up.
