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VOMS-Admin Retirement

Introduction

This document provides an overview of the planned retirement of support for VOMS-Admin in the OSG Software Stack.

Support for the VOMS infrastructure has three major components:

  1. VOMS-Admin: A web interface for maintaining the list of authorized users in a VO and their various authorizations (group membership, roles, attributes, etc).
  2. VOMS-Server: A TCP service which signs a cryptographic extension on an X509 proxy certificate asserting the authorizations available to the authenticated user.
  3. VOMS Client: Software for extracting and validating the signed VOMS extension from an X509 proxy. The validation is meant to be distributed: the VOMS client does not need to contact the VOMS-Admin server. However, OSG has historically used software such as GUMS or edg-mkgridmap to cache a list of authorizations from the VOMS-Admin interface, creating a dependency between VOMS client and VOMS-Admin.

VOMS-Admin is a large, complex Java web application. Over the last few years, upstream support has tailed off - particularly as OSG has been unable to update to VOMS-Admin version 3. As a result, the maintenance burden has largely fallen on the OSG Software team.

Given that VOMS-Admin is deeply tied to X509 security infrastructure - and is maintenance-only from OSG Software - there is no path forward to eliminate the use of X509 certificates in the web browser, a high-priority goal

In discussions with the OSG community, we have found very few VOs utilize VOMS-Admin to manage their VO users. Instead, the majority use VOMS-Admin to whitelist a pilot certificate: this can be done without a VOMS-Admin endpoint.

OSG's plans to retire VOMS-Admin has three major components:

  • (Sites) Enable distributed validation of VOMS extensions in the VOMS client.
  • (VOs) Migrate VOs that use VOMS only for pilot certificates to direct signing of VOMS proxies.
  • (VOs) Migrate remaining VOs to a central comanage instance for managing user authorizations; maintain a plugin to enable direct callouts from VOMS-Server to comanage for authorization lookups.

Site Transition Plans

We will release a configuration of the LCMAPS authorization framework that performs distributed verification of VOMS extensions; this verification eludes the need to contact the VOMS-Admin interface for a list of authorizations.

In 2015/2016, LCMAPS and GUMS were upgraded so GUMS skips the VOMS-Admin lookup when LCMAPS asserts the validation was performed. Hence, when GUMS sites update clients to the latest (April 2017) LCMAPS and HTCondor-CE releases, the callout to VOMS-Admin is no longer needed. Note: In parallel to the VOMS-Admin transition, OSG Software plans to retire GUMS. There is no need to complete one transition before the other.

Sites using edg-mkgridmap will need to use its replacement, lcmaps-plugins-voms (this process is documented here).

VO Transition Plans

Based on one-to-one discussions, we believe the majority of VOs only use VOMS-Admin to maintain a list of authorized pilots. For these VOs, we will help convert invocations of voms-proxy-init:

voms-proxy-init -voms hcc:/hcc/Role=pilot

to an equivalent call to voms-proxy-fake:

voms-proxy-fake -hostcert /etc/grid-security/voms/vomscert.pem \
                -hostkey /etc/grid-security/voms/vomskey.pem \
                -fqan /hcc/Role=pilot/Capability=NULL \
                -voms hcc -uri hcc-voms.unl.edu:15000

The latter command would typically be run on the VO's glideinWMS frontend host, requiring the service certificate currently on the VOMS-Admin server to be kept on the frontend host. The frontend's account may also need access to the certificate.

We plan to transition more complex VOs - those using VOMS-Admin to track membership in a VO - to comanage. It is not clear there are any such VOs that need support from OSG. If there are, a hosted version of comanage is expected to be available in summer 2017 from the CILogon 2.0 project. If you feel your VO is affected, please contact the OSG and we will build a custom timeline. If there are no such VOs, we will not need to adopt comanage for this use case (other uses of comanage are expected to proceed regardless).

Timeline

  • April 2017 (completed): lcmaps-plugins-voms shipped and supported by OSG.
  • May 2017 (completed): osg-configure and documentation necessary for using lcmaps-plugins-voms is shipped.
  • June 2017 (completed): OSG 3.4.0 is released without VOMS-Admin, edg-mkgridmap, or GUMS. Sites begin transition to validating VOMS extensions.
  • Summer 2017 (completed): As necessary, VOs are given access to a hosted comanage instance.
  • March 2017 (completed): First VOs begin to retire VOMS-Admin.
  • May 2018 (completed): Support is dropped for OSG 3.3 series; no further support for VOMS-Admin or GUMS is provided.