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).

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.

Protocol ideas¶

SRP-6a

"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.

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)