WLCG DOMA BDT Meeting

Wednesday 4 Jan 2023, 16:30 → 17:30 Europe/Zurich

Brian Paul Bockelman (University of Wisconsin Madison (US)), Maria Arsuaga Rios (CERN), Petr Vokac (Czech Technical University in Prague (CZ))

Topic: WLCG DOMA BDT Meeting (twiki)

1 News

Happy new year 2023, the year of the tokens for storage

• connected mostly people from US, because today is still CERN end-of-year closure

2 Transfers with tokens

Speaker: Francesco Giacomini (INFN CNAF)

User / group managed storage areas

• IAM admin have full access to all VO data on all storage sites that give access to the particular issuer
• it may be tricky to configure and use tokens for non-grid storage areas, e.g. ATLAS CERN group disk (ServiceX#507)
  • access to whole namespace with storage.read:/ can't be revoked in the subdirectories
    • OK for CMS where all users have read-only access to the all CMS data
    • no private data for users / groups - everything readable by any VO user
      • not so clear for ATLAS
      • user can change permission on EOS mounted as posix filesystem
        • revoke access to subdirs
  • site specific namespace would result in complicated IAM scope policies
    • e.g. "atlascerngroupdisk"
    • can't be fully enforced (no aud in IAM scope policy definition)
  • it may be tricky for users to understand which scopes they are allowed to use
    • e.g. storage.read:/atlascerngroupdisk/phys-higgs/ for access to root://eosatlas.cern.ch//eos/atlas/atlascerngroupdisk/phys-higgs
• it would be easier to use wlcg.groups for storage areas mounted also as a posix filesystem
  • e.g. /eos/atlas/atlascerngroupdisk is mounted as a posix filesystem (different permission model)
  • tricky / impossible to configure same access permissions with capability
  • groups doesn't provide storage.create functionality => we can't limit damage done by rogue jobs / tokens stolen from jobs

ATLAS XCache & tokens

• ATLAS just prepends XCache in the URL, e.g. root://xcache.example.com:1094//root://storage.example.com/path/to/file
• it is not clear which tokens should be used for XCache and than for final storage
  • storage.read:/root://storage.exmple.com(?)
  • different scope necessary for final storage
• used for job stage-in => not relevant for DC24, but we should try to identify all valid and problematic cases asap
  • some xroot:// (protocol) features may not work properly without updates / improvements / changes

Fermilab and storage access with tokens

• jobsub_lite uses SciTokens (https://scitokens.org) to authorize users to submit jobs, write to storage, etc.

3 Tape REST access

Speaker: Mihai PATRASCOIU (CERN)

4 Packet marking

Speakers: Marian Babik (CERN), Shawn Mc Kee (University of Michigan (US))

5 WebDAV Error Message Improvement Project

Discuss with experts improvements in the error messages produced by failed transfers.

Speaker: Stephan Lammel (Fermi National Accelerator Lab. (US))

6 AOB

WLCG JWT profile - group OR scope authorization

• brief discussion related to the long email thread "Tokens with groups and explicit AuthZ statements" in project-lcg-authz mailing list
• the whole email thread covers an edge case that most VOs should never face - combining scopes with wlcg.groups in one token
  • people seems not to be very concerned that e.g. dCache doesn't implement what's required by WLCG JWT profile
  • LHC experiments plans to avoid tokens that combine scopes and wlcg.groups
• we could easily survive even if current "OR" is replaced with "implementation specific behavior"