Some integrators render our videoconference inside an iframe, where
our cookie-based authentication does not work: our cookies are
SameSite=Lax/Strict, so the iframe drops them.
We looked at what Jitsi offers: a shared secret used to sign JWTs
that authenticate users coming from external services. Since we
already expose an external API where third parties authenticate as
a given user, it was simpler for us to add an exchange mechanism on
top of that.
Flow:
* Through the external API, mint a short-lived, single-use exchange
code for a user.
* The third party hands that code to the frontend as a URL fragment.
* The frontend exchanges the code for a longer-lived JWT that can be
used to query the regular API viewsets.
Known limitations and follow-ups:
* At some point it would be nice to shorten the JWT lifetime and
add a refresh mechanism. This will be handled in a follow-up PR
when actually needed.
* CSP rules to control which origins are allowed to embed the app
in an iframe still need to be added.
* This alternative authentication cannot easily be scoped to a
subset of endpoints without adding a lot of complexity, so it is
accepted globally on the API for now.
lebaudantoine