Using a dedicated type allows to record in the type the guarantees that we
provide, such as scheme being HTTPS and authority being present. Allows to
replace ugly `fromJust` and such with direct field access.
Allow keys to specify expiration time using w3c security vocabulary. If a key
has expired, we treat it like sig validation failure and re-fetch the key from
the other server. And we never accept a sig, even a valid sig, if the key has
expired.
Since servers keep actors and keys in the DB, expiration can be a nice way to
ask that keys aren't used more than we want them to. The security vocab spec
also recommends to set expiration time on keys, so it's nice to support this
feature.
It's now possible for activities we be attributed to actors that have more than
one key. We allow up to 2 keys. We also store in the DB. Scaling to support any
number of keys is trivial, but I'm limiting to 2 to avoid potential trouble and
because 2 is the actual number we need.
By having 2 keys, and replacing only one of them in each rotation, we avoid
race conditions. With 1 key, the following can happen:
1. We send an activity to another server
2. We rotate our key
3. The server reaches the activity in its processing queue, tries to verify our
request signature, but fails because it can't fetch the key. It's the old
key and we discarded it already, replaced it with the new one
When we use 2 keys, the previous key remains available and other servers have
time to finish processing our requests signed with that key. We can safely
rotate, without worrying about whether the user sent anything right before the
rotation time.
Caveat: With this feature, we allow OTHER servers to rotate freely. It's safe
because it's optional, but it's just Vervis right now. Once Vervis itself
starts using 2 keys, it will be able to rotate freely without race condition
risk, but probably Mastodon etc. won't accept its signatures because of the use
of 2 keys and because they're server-scope keys.
Maybe I can get these features adopted by the fediverse?
* Repo collab now supports basic default roles developer/user/guest like
project collab does
* User/Anon collab for repos and projects are now stored as fields instead of
in dedicated tables, there was never a need for dedicated tables but I didn't
see that before
* Repo push op is now part of `ProjectOperation`
* `RepoRole` and related code has been entirely removed, only project roles
remain and they're used for both repos and projects
* This is the first not-totally-trivial DB migration in Vervis, it's automatic
but please be careful and report errors
Until now the list of DB migration actions was incomplete, containing only
changes made since I added the migration system itself. It now contains the
2016-08-04 model, and then every change made since then.
IMPORTANT: The 2016-08-04 instance doesn't have a schema version entity at all,
so it is assigned version 0, while the actual version of its schema is 1. I'm
going to patch persistent-migration to allow it to be 1, making the migration
path smooth.
