Internet Engineering Task Force (IETF) M. Bjorklund Request for Comments: 8527 Tail-f Systems Updates: 8040 J. Schoenwaelder Category: Standards Track Jacobs University ISSN: 2070-1721 P. Shafer Juniper Networks K. Watsen Watsen Networks R. Wilton Cisco Systems March 2019
RESTCONF Extensions to Support the Network Management Datastore Architecture
Abstract
This document extends the RESTCONF protocol defined in RFC 8040 in order to support the Network Management Datastore Architecture (NMDA) defined in RFC 8342.
This document updates RFC 8040 by introducing new datastore resources, adding a new query parameter, and requiring the usage of the YANG library (described in RFC 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 in Section 2 of RFC 7841.
Information about the current status of this document, any errata, and how to provide feedback on it may be obtained at https://www.rfc-editor.org/info/rfc8527.
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RFC 8527 RESTCONF Extensions for the NMDA March 2019
Copyright Notice
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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. Terminology ................................................3 2. Datastore and YANG Library Requirements .........................3 3. RESTCONF Extensions .............................................4 3.1. New Datastore Resources ....................................4 3.2. Protocol Operations ........................................5 3.2.1. The "with-defaults" Query Parameter on the Operational State Datastore .........................5 3.2.2. New "with-origin" Query Parameter ...................6 4. IANA Considerations .............................................7 5. Security Considerations .........................................7 6. Normative References ............................................7 Authors' Addresses .................................................9
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RFC 8527 RESTCONF Extensions for the NMDA March 2019
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.
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 in BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all capitals, as shown here.
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.
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RFC 8527 RESTCONF Extensions for the NMDA March 2019
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 in Section 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.
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RFC 8527 RESTCONF Extensions for the NMDA March 2019
The protocol operations available for the new datastore resources (see Section 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 in Section 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:
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 in Section 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 in Section 4.8.9 of [RFC8040].
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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 in Section 4.8.9 of [RFC8040].
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 in Section 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:
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 (see Section 12 of [RFC8040]) apply to the new RESTCONF datastore resources defined in this document.