Rucio & FTS

Participants: Andrea, Mario, BrianB, Rose, Linda, BrianD, Federica, Jim, John, Maarten, Marcelo, Martin, Mihai, Timothy, Petr, Roberta, Rizart, Alison, Tom, Francesco, Xiaomei

Notes:

• 3 scenarios proposed in attached slides, number 2 was the best option
• Questions
  • Do storage elements just see the “Rucio server” tokens, or do they see individuals?
    • Currently supports both a shared user (for transfers) and user proxies (for uploads and downloads), traceability required
    • Depends whether group based or capability based wanted? Initial reaction = capability
  • How does Rucio know which scopes should be requested in a token?
    • Should know which operations are required on which files
    • If user tokens required may need to set up group based capability authorisation in IAM (could get large and a lot of logic in IAM)
      • Hopefully just simple rules in IAM, e.g. anyone in the VO can read a particular path
  • Handling of refresh tokens?
    • Not really done (would go back to the server and get a new token)
  • Traceability
    • We need a way for Rucio server to be able to request a token for a particular user using its own credentials
      • Possibly “act” actor claim if getting tokens where subject is “Rucio server” i.e. shared credential
      • Should ensure the “sub” is maintained somehow for traceability purposes
  • Which flow used at “point 3”? Client credentials or token exchange?
    • Client credentials, with “act” actor embedded to preserve original subject
      • Storage elements would have to handle slightly more complex tokens
      • Some standards, e.g. UserInfo would not work
    • Token exchange
      • May require more logic within IAM r.e scopes
  • What does the Rucio Client do when it gets an error or an expired token?
    • Requests a new token from the Rucio Server (who goes back to IAM)
• We typically want a token for each storage element in case it fails and could be retried
• Rucio Client = public client?
  • Could be reasonable, if token just gets back basic permission about user

Actions:

• Hannah: schedule next call for 7th at 15:00
• Andrea: clarify token exchange and “act” claim
• Andrea/Francesco: Make more detailed slide on “point 3”