Arvados

h1. Federated identity

A person should be able to create an account and get a token from a single identity provider, and use that token to access private/protected resources on multiple Arvados clusters.

Motivating use cases:

* A user on cluster B shares a project with a user on cluster A.

* A container running on cluster A reads and writes data on cluster B.

* A user logged in to Workbench A can search/view/download/upload collections at cluster B.

Configuration examples:

* An organization has 5 clusters, but only one of them has user accounts and roles in its database.

* An on-premise cluster runs containers that use public data stored in the cloud (without mirroring the data locally).

h2. Design sketch

Each Arvados client must be able to prove to cluster B that it is authorized by cluster A to act on behalf of a user account which is controlled by cluster A. This must not involve giving enough information to cluster B to act on behalf of the user account: for example, the client cannot simply give cluster B its cluster A token for the purpose of doing a canary query.

h2. Protocol ideas

"SRP-6a":https://en.wikipedia.org/wiki/Secure_Remote_Password_protocol

"Salted tokens": instead of passing its literal token, the client passes the token UUID and @HMAC(token, "bbbbb")@ when sending a request to cluster B (where "bbbbb" is cluster B's cluster ID / UUID prefix). Cluster B validates the request by passing those two parameters untouched to a "verify request" ("no-op") endpoint at cluster A.

(PA) an even simpler approach would be be to contact cluster A to get a scoped token which only allows "GET /users/current" on cluster A but is accepted by cluster B as an [all] token for that user.

h2. TODO

Things to address

* how to sync groups

* diagrams

* mnemonic cluster names / more concrete examples (including who is reachable on the internet)

* [how] do you get a list of users you can share stuff with?

* clarify what UUIDs look like (some people have A uuids, some have B uuids)