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Internet Engineering Task Force (IETF) M. BjorklundRequest for Comments: 8527 Tail-f SystemsUpdates:8040 J. SchoenwaelderCategory: Standards Track Jacobs UniversityISSN: 2070-1721 P. Shafer Juniper Networks K. Watsen Watsen Networks R. Wilton Cisco Systems March 2019RESTCONF Extensions to Support theNetwork Management Datastore ArchitectureAbstract This document extends the RESTCONF protocol defined inRFC 8040 in order to support the Network Management Datastore Architecture (NMDA) defined inRFC 8342. This document updatesRFC 8040 by introducing new datastore resources, adding a new query parameter, and requiring the usage of the YANG library (described inRFC 8525) by RESTCONF servers implementing the NMDA.Status of This Memo This is an Internet Standards Track document. This document is a product of the Internet Engineering Task Force (IETF). It represents the consensus of the IETF community. It has received public review and has been approved for publication by the Internet Engineering Steering Group (IESG). Further information on Internet Standards is available inSection 2 of RFC 7841. Information about the current status of this document, any errata, and how to provide feedback on it may be obtained athttps://www.rfc-editor.org/info/rfc8527.Bjorklund, et al. Standards Track [Page 1]

RFC 8527 RESTCONF Extensions for the NMDA March 2019Copyright Notice Copyright (c) 2019 IETF Trust and the persons identified as the document authors. All rights reserved. This document is subject toBCP 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 Contents1. Introduction ....................................................31.1. Terminology ................................................32. Datastore and YANG Library Requirements .........................33. RESTCONF Extensions .............................................43.1. New Datastore Resources ....................................43.2. Protocol Operations ........................................5 3.2.1. The "with-defaults" Query Parameter on the Operational State Datastore .........................53.2.2. New "with-origin" Query Parameter ...................64. IANA Considerations .............................................75. Security Considerations .........................................76. Normative References ............................................7 Authors' Addresses .................................................9Bjorklund, et al. Standards Track [Page 2]

RFC 8527 RESTCONF Extensions for the NMDA March 20191. Introduction This document extends the RESTCONF protocol defined in [RFC8040] in order to support the Network Management Datastore Architecture (NMDA) defined in [RFC8342]. This document updates [RFC8040] in order to enable RESTCONF clients to discover which datastores are supported by the RESTCONF server, determine which modules are supported in each datastore, and interact with all the datastores supported by the NMDA. Specifically, the update introduces new datastore resources, adds a new query parameter, and requires the usage of the YANG library [RFC8525] by RESTCONF servers implementing the NMDA. The solution presented in this document is backwards compatible with [RFC8040]. This is achieved by only adding new resources and leaving the semantics of the existing resources unchanged.1.1. Terminology This document uses the terminology defined by the NMDA [RFC8342]. The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described inBCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all capitals, as shown here.2. Datastore and YANG Library Requirements An NMDA-compliant RESTCONF server MUST support the operational state datastore and MUST implement at least revision 2019-01-04 of the "ietf-yang-library" module defined in [RFC8525]. Such a server identifies that it supports the NMDA both by implementing the {+restconf}/ds/ietf-datastores:operational resource and by implementing at least revision 2019-01-04 of the "ietf-yang-library" module. A RESTCONF client can test if a server supports the NMDA by using either the HEAD or GET methods on {+restconf}/ds/ietf- datastores:operational. A RESTCONF client can discover which datastores and YANG modules the server supports by reading the YANG library information from the operational state datastore.Bjorklund, et al. Standards Track [Page 3]

RFC 8527            RESTCONF Extensions for the NMDA          March 20193.  RESTCONF Extensions   This section describes the RESTCONF extensions needed to support the   NMDA.3.1.  New Datastore Resources   This document defines a set of new resources representing datastores   as defined in [RFC8342].  These resources are available using the   following resource path template:     {+restconf}/ds/<datastore>   The <datastore> path component is encoded as an "identityref"   according to the JSON encoding rules for identities, defined inSection 6.8 of [RFC7951].  The namespace-qualified form MUST be used.   Such an identity MUST be derived from the "datastore" identity   defined in the "ietf-datastores" YANG module [RFC8342].   Specifically:   o  The resource {+restconf}/ds/ietf-datastores:operational refers to      the operational state datastore.   o  The resource {+restconf}/ds/ietf-datastores:running refers to the      running configuration datastore.   o  The resource {+restconf}/ds/ietf-datastores:intended refers to the      intended configuration datastore.   An NMDA-compliant server MUST implement {+restconf}/ds/ietf-   datastores:operational.  Other datastore resources MAY be   implemented.   YANG actions can only be invoked in {+restconf}/ds/ietf-   datastores:operational.   As an example, if a server implements a datastore called   "ds-ephemeral", defined in a module called "example-ds-ephemeral",   then the server would implement the resource {+restconf}/ds/example-   ds-ephemeral:ds-ephemeral.Bjorklund, et al.            Standards Track                    [Page 4]

RFC 8527            RESTCONF Extensions for the NMDA          March 20193.2.  Protocol Operations   The protocol operations available for the new datastore resources   (seeSection 3.1) are the same as the protocol operations defined in   [RFC8040] for the {+restconf}/data resource with the following   exceptions:   o  Dynamic configuration datastores are excluded, as each dynamic      configuration datastore definition needs to be reviewed for what      protocol operations it supports.   o  Some datastores are read-only by nature (e.g., <intended>); hence,      any attempt to modify these datastores will fail.  A server MUST      return a response with a "405 Method Not Allowed" status-line and      an error-tag value of "operation-not-supported".   o  The semantics of the "with-defaults" query parameter      (Section 4.8.9 of [RFC8040]) differ when interacting with the      operational state datastore.  The semantics are described inSection 3.2.1.   o[RFC8040], Section 3.5.4, paragraph 3 does not apply when      interacting with any resource under {+restconf}/ds.3.2.1.  The "with-defaults" Query Parameter on the Operational State        Datastore   Support for the "with-defaults" query parameter (Section 4.8.9 of   [RFC8040]) is OPTIONAL when interacting with {+restconf}/ds/ietf-   datastores:operational.  The associated capability to indicate a   server's support is identified with the URI:     urn:ietf:params:restconf:capability:with-operational-defaults:1.0   For servers that support it, the behavior of the "with-defaults"   query parameter on the operational state datastore is defined as   follows:   o  If no "with-defaults" query parameter is specified, or if it is      set to "explicit", "report-all", or "report-all-tagged", then the      "in use" values, as defined inSection 5.3 of [RFC8342], are      returned from the operational state datastore, even if a node      happens to have a default statement in the YANG module and this      default value is being used by the server.  If the "with-defaults"      parameter is set to "report-all-tagged", any values that match the      schema default are tagged with additional metadata, as described      inSection 4.8.9 of [RFC8040].Bjorklund, et al.            Standards Track                    [Page 5]

RFC 8527            RESTCONF Extensions for the NMDA          March 2019   o  If the "with-defaults" query parameter is set to "trim", all "in      use" values are returned, except that the output is filtered to      exclude any values that match the default defined in the YANG      schema.   Servers are not required to support all values in the "with-defaults"   query parameter on the operational state datastore.  If a request is   made using a value that is not supported, then the error handling   behavior is as described inSection 4.8.9 of [RFC8040].3.2.2.  New "with-origin" Query Parameter   A new query parameter named "with-origin" is added to the GET   operation.  If present, it requests that the server includes "origin"   metadata annotations in its response, as detailed in the NMDA.  This   parameter is only valid when querying {+restconf}/ds/ietf-   datastores:operational or any datastores with identities derived from   the "operational" identity.  Otherwise, if an invalid datastore is   specified, then the server MUST return a response with a "400 Bad   Request" status-line, using an error-tag value of "invalid-value".   "origin" metadata annotations are not included unless a client   explicitly requests them.   Data in the operational state datatstore can come from multiple   sources.  The server should return the "origin" metadata annotation   value that most accurately indicates the source of the operational   value, as specified inSection 5.3.4 of [RFC8342].   When encoding the "origin" metadata annotation for a hierarchy of   returned nodes, the annotation can be omitted for a child node when   the value matches that of the parent node, as described in the   "ietf-origin" YANG module [RFC8342].   Support for the "with-origin" query parameter is OPTIONAL.  It is   identified with the URI:     urn:ietf:params:restconf:capability:with-origin:1.0Bjorklund, et al.            Standards Track                    [Page 6]

RFC 8527 RESTCONF Extensions for the NMDA March 20194. IANA Considerations This document defines two capability identifier URNs in the "RESTCONF Capability URNs" registry defined in [RFC8040]: Index Capability Identifier --------------------- :with-origin urn:ietf:params:restconf:capability:with-origin:1.0 :with-operational-defaults urn:ietf:params:restconf:capability:with-operational-defaults:1.05. Security Considerations This document extends the RESTCONF protocol by introducing new datastore resources. The lowest RESTCONF layer is HTTPS, and the mandatory-to-implement secure transport is TLS [RFC8446]. The RESTCONF protocol uses the network configuration access control model [RFC8341], which provides the means to restrict access for particular RESTCONF users to a preconfigured subset of all available RESTCONF protocol operations and content. The security constraints for the base RESTCONF protocol (seeSection 12 of [RFC8040]) apply to the new RESTCONF datastore resources defined in this document.6. Normative References [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels",BCP 14,RFC 2119, DOI 10.17487/RFC2119, March 1997, <https://www.rfc-editor.org/info/rfc2119>. [RFC7951] Lhotka, L., "JSON Encoding of Data Modeled with YANG",RFC 7951, DOI 10.17487/RFC7951, August 2016, <https://www.rfc-editor.org/info/rfc7951>. [RFC8040] Bierman, A., Bjorklund, M., and K. Watsen, "RESTCONF Protocol",RFC 8040, DOI 10.17487/RFC8040, January 2017, <https://www.rfc-editor.org/info/rfc8040>. [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase inRFC2119 Key Words",BCP 14,RFC 8174, DOI 10.17487/RFC8174, May 2017, <https://www.rfc-editor.org/info/rfc8174>.Bjorklund, et al. Standards Track [Page 7]

RFC 8527            RESTCONF Extensions for the NMDA          March 2019   [RFC8341]  Bierman, A. and M. Bjorklund, "Network Configuration              Access Control Model", STD 91,RFC 8341,              DOI 10.17487/RFC8341, March 2018,              <https://www.rfc-editor.org/info/rfc8341>.   [RFC8342]  Bjorklund, M., Schoenwaelder, J., Shafer, P., Watsen, K.,              and R. Wilton, "Network Management Datastore Architecture              (NMDA)",RFC 8342, DOI 10.17487/RFC8342, March 2018,              <https://www.rfc-editor.org/info/rfc8342>.   [RFC8446]  Rescorla, E., "The Transport Layer Security (TLS) Protocol              Version 1.3",RFC 8446, DOI 10.17487/RFC8446, August 2018,              <https://www.rfc-editor.org/info/rfc8446>.   [RFC8525]  Bierman, A., Bjorklund, M., Schoenwaelder, J., Watsen, K.,              and R. Wilton, "YANG Library",RFC 8525,              DOI 10.17487/RFC8525, March 2019,              <https://www.rfc-editor.org/info/rfc8525>.Bjorklund, et al.            Standards Track                    [Page 8]

RFC 8527            RESTCONF Extensions for the NMDA          March 2019Authors' Addresses   Martin Bjorklund   Tail-f Systems   Email: mbj@tail-f.com   Juergen Schoenwaelder   Jacobs University   Email: j.schoenwaelder@jacobs-university.de   Phil Shafer   Juniper Networks   Email: phil@juniper.net   Kent Watsen   Watsen Networks   Email: kent+ietf@watsen.net   Robert Wilton   Cisco Systems   Email: rwilton@cisco.comBjorklund, et al.            Standards Track                    [Page 9]

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