Network Working Group R. Wilton, Ed. Internet-Draft R. Rahman, Ed. Updates: 7950,8407,8525 (if approved) Cisco Systems, Inc. Intended status: Standards Track B. Lengyel, Ed. Expires: January 11, 2021 Ericsson J. Clarke Cisco Systems, Inc. J. Sterne Nokia B. Claise Cisco Systems, Inc. K. D'Souza AT&T July 10, 2020 Updated YANG Module Revision Handling draft-ietf-netmod-yang-module-versioning-01 Abstract This document specifies a new YANG module update procedure that can document when non-backwards-compatible changes have occurred during the evolution of a YANG module. It extends the YANG import statement with an earliest revision filter to better represent inter-module dependencies. It provides help and guidelines for managing the lifecycle of YANG modules and individual schema nodes. It provides a mechanism, via the revision-label YANG extension, to specify a revision identifier for YANG modules. This document updates RFC 7950, RFC 8407 and RFC 8525. Status of This Memo This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet- Drafts is at https://datatracker.ietf.org/drafts/current/. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." This Internet-Draft will expire on January 11, 2021. Wilton, et al. Expires January 11, 2021 [Page 1]
Internet-Draft Updated YANG Module Revision Handling July 2020 Copyright Notice Copyright (c) 2020 IETF Trust and the persons identified as the document authors. All rights reserved. This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (https://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 1.1. Updates to YANG RFCs . . . . . . . . . . . . . . . . . . 4 2. Terminology and Conventions . . . . . . . . . . . . . . . . . 4 3. Refinements to YANG revision handling . . . . . . . . . . . . 5 3.1. Updating a YANG module with a new revision . . . . . . . 5 3.1.1. Backwards-compatible changes . . . . . . . . . . . . 6 3.1.2. Non-backwards-compatible changes . . . . . . . . . . 6 3.2. nbc-changes revision extension statement . . . . . . . . 7 3.3. Revision label . . . . . . . . . . . . . . . . . . . . . 7 3.3.1. Revision label scheme extension statement . . . . . . 8 3.4. Examples for updating the YANG module revision history . 8 4. Import by derived revision . . . . . . . . . . . . . . . . . 11 4.1. Module import examples . . . . . . . . . . . . . . . . . 12 5. Updates to ietf-yang-library . . . . . . . . . . . . . . . . 14 5.1. Resolving ambiguous module imports . . . . . . . . . . . 14 5.2. YANG library versioning augmentations . . . . . . . . . . 15 5.2.1. Advertising revision-label . . . . . . . . . . . . . 15 5.2.2. Reporting how deprecated and obsolete nodes are handled . . . . . . . . . . . . . . . . . . . . . . . 15 6. Versioning of YANG instance data . . . . . . . . . . . . . . 16 7. Guidelines for using the YANG module update rules . . . . . . 16 7.1. Guidelines for YANG module authors . . . . . . . . . . . 16 7.1.1. Making non-backwards-compatible changes to a YANG module . . . . . . . . . . . . . . . . . . . . . . . 17 7.2. Versioning Considerations for Clients . . . . . . . . . . 18 8. Module Versioning Extension YANG Modules . . . . . . . . . . 18 9. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 26 10. Security Considerations . . . . . . . . . . . . . . . . . . . 27 11. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 27 11.1. YANG Module Registrations . . . . . . . . . . . . . . . 27 11.2. Instructions . . . . . . . . . . . . . . . . . . . . . . 28 Wilton, et al. Expires January 11, 2021 [Page 2]
Internet-Draft Updated YANG Module Revision Handling July 2020 12. References . . . . . . . . . . . . . . . . . . . . . . . . . 28 12.1. Normative References . . . . . . . . . . . . . . . . . . 28 12.2. Informative References . . . . . . . . . . . . . . . . . 29 Appendix A. Examples of changes that are NBC . . . . . . . . . . 29 Appendix B. Examples of applying the NBC change guidelines . . . 30 B.1. Removing a data node . . . . . . . . . . . . . . . . . . 30 B.2. Changing the type of a leaf node . . . . . . . . . . . . 31 B.3. Reducing the range of a leaf node . . . . . . . . . . . . 32 B.4. Changing the key of a list . . . . . . . . . . . . . . . 32 B.5. Renaming a node . . . . . . . . . . . . . . . . . . . . . 33 B.6. Changing a default value . . . . . . . . . . . . . . . . 34 Appendix C. Changes between revisions . . . . . . . . . . . . . 34 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 34 1. Introduction This document defines a solution to the YANG module lifecycle problems described in [I-D.ietf-netmod-yang-versioning-reqs]. Complementary documents provide a complete solution to the YANG versioning requirements, with the overall relationship of the solution drafts described in [