| Network Working Group | A. Bierman |
| Internet-Draft | YumaWorks |
| Intended status: Standards Track | M. Bjorklund |
| Expires: January 7, 2016 | Tail-f Systems |
| K. Watsen | |
| Juniper Networks | |
| July 6, 2015 |
YANG Patch Media Type
draft-ietf-netconf-yang-patch-05
This document describes a method for applying patches to NETCONF datastores using data defined with the YANG data modeling language.
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 http://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 7, 2016.
Copyright (c) 2015 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 (http://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.
There is a need for standard mechanisms to patch NETCONF [RFC6241] datastores which contain conceptual data that conforms to schema specified with YANG [RFC6020]. An "ordered edit list" approach is needed to provide client developers with a simpler edit request format that can be more efficient and also allow more precise client control of the transaction procedure than existing mechanisms.
This document defines a media type for a YANG-based editing mechanism that can be used with the HTTP PATCH method [RFC5789]. YANG Patch is designed to support the RESTCONF protocol, defined in [I-D.ietf-netconf-restconf].
The keywords "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].
The following terms are defined in [RFC6241]:
The following terms are defined in [RFC2616]:
The following terms are defined in [RFC6020]:
The following terms are defined in [I-D.ietf-netconf-restconf]:
The following terms are used within this document:
A simplified graphical representation of the data model is used in this document. The meaning of the symbols in these diagrams is as follows:
A "YANG Patch" is an ordered list of edits that are applied to the target datastore by the server. The specific fields are defined in the YANG module in Section 3.
For RESTCONF, the YANG Patch operation is invoked by the client by sending a PATCH method request with the YANG Patch media type. A message body representing the YANG Patch input parameters MUST be provided.
The RESTCONF server MUST return the Accept-Patch header in an OPTIONS response, as specified in [RFC5789], which includes the media type for YANG Patch.
Example:
Accept-Patch: application/yang.patch
The YANG Patch operation uses a conceptual root within a NETCONF configuration datastore to identity the patch point for the edit operation. This root can be the datastore itself, or 1 or more data nodes within the datastore.
For RESTCONF, the target resource is derived from the request URI.
A YANG patch is optionally identified by a unique "patch‑id" and it may have an optional comment. A patch is an ordered collection of edits. Each edit is identified by an "edit‑id" and it has an edit operation (create, delete, insert, merge, move, replace, remove) that is applied to the target resource. Each edit can be applied to a sub-resource "target" within the target resource. If the operation is "insert" or "move", then the "where" parameter indicates how the node is inserted or moved. For values "before" and "after", the "point" parameter specifies the data node insertion point.
A data element representing the YANG Patch is sent by the client to specify the edit operation request. When used with the HTTP PATCH method, this data is identified by the YANG Patch media type.
YANG Tree Diagram For "yang‑patch" Container
+--rw yang-patch
+--rw patch-id? string
+--rw comment? string
+--rw edit [edit-id]
+--rw edit-id string
+--rw operation enumeration
+--rw target target-resource-offset
+--rw point? target-resource-offset
+--rw where? enumeration
+--rw value
A data element representing the YANG Patch Status is returned to the client to report the detailed status of the edit operation. When used with the HTTP PATCH method, this data is identified by the YANG Patch Status media type, and the syntax specification is defined in Section 3.
YANG Tree Diagram For "yang‑patch‑status" Container:
+--rw yang-patch-status
+--rw patch-id? string
+--rw (global-status)?
| +--:(global-errors)
| | +--ro errors
| |
| +--:(ok)
| +--rw ok? empty
+--rw edit-status
+--rw edit [edit-id]
+--rw edit-id string
+--rw (edit-status-choice)?
+--:(ok)
| +--rw ok? empty
+--:(errors)
+--ro errors
The target data node for each edit operation is determined by the value of the target resource in the request and the "target" leaf within each "edit" entry.
If the target resource specified in the request URI identifies a datastore resource, then the path string in the "target" leaf is an absolute path expression. The first node specified in the "target" leaf is a top-level data node defined within a YANG module.
If the target resource specified in the request URI identifies a data resource, then the path string in the "target" leaf is a relative path expression. The first node specified in the "target" leaf is a child node of the data node associated with the target resource.
Each YANG patch edit specifies one edit operation on the target data node. The set of operations is aligned with the NETCONF edit operations, but also includes some new operations.
| Operation | Description |
|---|---|
| create | create a new data resource if it does not already exist or error |
| delete | delete a data resource if it already exists or error |
| insert | insert a new user-ordered data resource |
| merge | merge the edit value with the target data resource; create if it does not already exist |
| move | re-order the target data resource |
| replace | replace the target data resource with the edit value |
| remove | remove a data resource if it already exists or no error |
If a well-formed, schema-valid YANG Patch message is received, then the server will process the supplied edits in ascending order. The following error modes apply to the processing of this edit list:
All the specified edits MUST be applied or the target datastore contents MUST be returned to its original state before the PATCH method started.
The server will save the running datastore to non-volatile storage if it has changed, after the edits have been successfully completed.
A URI is defined to identify the YANG Patch extension to the base RESTCONF protocol. If the server supports the YANG Patch media type, then the "yang‑patch" RESTCONF capability defined in Section 4.4 MUST be present in the "capability" leaf-list in the "ietf‑restconf‑monitoring" module defined in [I-D.ietf-netconf-restconf].
The "ietf‑yang‑patch" module defines conceptual definitions with the 'restconf‑media‑type' extension statements, which are not meant to be implemented as datastore contents by a server.
The "ietf‑restconf" module from [I-D.ietf-netconf-restconf] is used by this module for the 'restconf‑media‑type' extension definition.
RFC Ed.: update the date below with the date of RFC publication and remove this note.
<CODE BEGINS> file "ietf-yang-patch@2015-04-30.yang"
module ietf-yang-patch {
namespace "urn:ietf:params:xml:ns:yang:ietf-yang-patch";
prefix "ypatch";
import ietf-yang-types { prefix yang; }
import ietf-restconf {
prefix rc;
revision-date 2015-06-04;
}
organization
"IETF NETCONF (Network Configuration) Working Group";
contact
"WG Web: <http://tools.ietf.org/wg/netconf/>
WG List: <mailto:netconf@ietf.org>
WG Chair: Mehmet Ersue
<mailto:mehmet.ersue@nsn.com>
WG Chair: Mahesh Jethanandani
<mailto:mjethanandani@gmail.com>
Editor: Andy Bierman
<mailto:andy@yumaworks.com>
Editor: Martin Bjorklund
<mailto:mbj@tail-f.com>
Editor: Kent Watsen
<mailto:kwatsen@juniper.net>";
description
"This module contains conceptual YANG specifications
for the YANG Patch and YANG Patch Status data structures.
Note that the YANG definitions within this module do not
represent configuration data of any kind.
The YANG grouping statements provide a normative syntax
for XML and JSON message encoding purposes.
Copyright (c) 2015 IETF Trust and the persons identified as
authors of the code. All rights reserved.
Redistribution and use in source and binary forms, with or
without modification, is permitted pursuant to, and subject
to the license terms contained in, the Simplified BSD License
set forth in Section 4.c of the IETF Trust's Legal Provisions
Relating to IETF Documents
(http://trustee.ietf.org/license-info).
This version of this YANG module is part of RFC XXXX; see
the RFC itself for full legal notices.";
// RFC Ed.: replace XXXX with actual RFC number and remove this
// note.
// RFC Ed.: remove this note
// Note: extracted from draft-ietf-netconf-yang-patch-04.txt
// RFC Ed.: update the date below with the date of RFC publication
// and remove this note.
revision 2015-06-04 {
description
"Initial revision.";
reference
"RFC XXXX: YANG Patch Media Type.";
}
typedef target-resource-offset {
type yang:xpath1.0;
description
"Contains an XPath absolute path expression identifying
a sub-resource within the target resource.
The document root for this XPath expression is the
target resource that is specified in the
protocol operation (e.g., the URI for the PATCH request).";
}
rc:restconf-media-type "application/yang.patch" {
uses yang-patch;
}
rc:restconf-media-type "application/yang.patch-status" {
uses yang-patch-status;
}
grouping yang-patch {
description
"A grouping that contains a YANG container
representing the syntax and semantics of a
YANG Patch edit request message.";
container yang-patch {
description
"Represents a conceptual sequence of datastore edits,
called a patch. Each patch is given a client-assigned
patch identifier. Each edit MUST be applied
in ascending order, and all edits MUST be applied.
If any errors occur, then the target datastore MUST NOT
be changed by the patch operation.
YANG datastore validation (defined in RFC 6020, section
8.3.3) is performed before any edits have been applied
to the running datastore.
It is possible for a datastore constraint violation to occur
due to any node in the datastore, including nodes not
included in the edit list. Any validation errors MUST
be reported in the reply message.";
reference
"RFC 6020, section 8.3.";
leaf patch-id {
type string;
description
"An arbitrary string provided by the client to identify
the entire patch. This value SHOULD be present in any
audit logging records generated by the server for the
patch. Error messages returned by the server pertaining
to this patch will be identified by this patch-id value.";
}
leaf comment {
type string;
description
"An arbitrary string provided by the client to describe
the entire patch. This value SHOULD be present in any
audit logging records generated by the server for the
patch.";
}
list edit {
key edit-id;
ordered-by user;
description
"Represents one edit within the YANG Patch
request message. The edit list is applied
in the following manner:
- The first edit is conceptually applied to a copy
of the existing target datastore, e.g., the
running configuration datastore.
- Each ascending edit is conceptually applied to
the result of the previous edit(s).
- After all edits have been successfully processed,
the result is validated according to YANG constraints.
- If successful, the server will attempt to apply
the result to the target datastore. ";
leaf edit-id {
type string;
description
"Arbitrary string index for the edit.
Error messages returned by the server pertaining
to a specific edit will be identified by this
value.";
}
leaf operation {
type enumeration {
enum create {
description
"The target data node is created using the
supplied value, only if it does not already
exist.";
}
enum delete {
description
"Delete the target node, only if the data resource
currently exists, otherwise return an error.";
}
enum insert {
description
"Insert the supplied value into a user-ordered
list or leaf-list entry. The target node must
represent a new data resource. If the 'where'
parameter is set to 'before' or 'after', then
the 'point' parameter identifies the insertion
point for the target node.";
}
enum merge {
description
"The supplied value is merged with the target data
node.";
}
enum move {
description
"Move the target node. Reorder a user-ordered
list or leaf-list. The target node must represent
an existing data resource. If the 'where' parameter
is set to 'before' or 'after', then the 'point'
parameter identifies the insertion point to move
the target node.";
}
enum replace {
description
"The supplied value is used to replace the target
data node.";
}
enum remove {
description
"Delete the target node if it currently exists.";
}
}
mandatory true;
description
"The datastore operation requested for the associated
edit entry";
}
leaf target {
type target-resource-offset;
mandatory true;
description
"Identifies the target data resource for the edit
operation.";
}
leaf point {
when "(../operation = 'insert' or " +
"../operation = 'move') and " +
"(../where = 'before' or ../where = 'after')" {
description
"Point leaf only applies for insert or move
operations, before or after an existing entry.";
}
type target-resource-offset;
description
"The absolute URL path for the data node that is being
used as the insertion point or move point for the
target of this edit entry.";
}
leaf where {
when "../operation = 'insert' or ../operation = 'move'" {
description
"Where leaf only applies for insert or move
operations.";
}
type enumeration {
enum before {
description
"Insert or move a data node before the data resource
identified by the 'point' parameter.";
}
enum after {
description
"Insert or move a data node after the data resource
identified by the 'point' parameter.";
}
enum first {
description
"Insert or move a data node so it becomes ordered
as the first entry.";
}
enum last {
description
"Insert or move a data node so it becomes ordered
as the last entry.";
}
}
default last;
description
"Identifies where a data resource will be inserted or
moved. YANG only allows these operations for
list and leaf-list data nodes that are ordered-by
user.";
}
anyxml value {
when "(../operation = 'create' or " +
"../operation = 'merge' " +
"or ../operation = 'replace' or " +
"../operation = 'insert')" {
description
"Value node only used for create, merge,
replace, and insert operations";
}
description
"Value used for this edit operation.
The anyxml value MUST represent a container with
exactly one child node, which MUST identify the
target resource associated with the 'target' leaf.
For example, suppose the target node is a YANG container
named foo:
container foo {
leaf a { type string; }
leaf b { type int32; }
}
The value node will contain one instance of foo:
<value>
<foo xmlns='example-foo-namespace'>
<a>some value</a>
<b>42</b>
</foo>
</value>
";
}
}
}
} // grouping yang-patch
grouping yang-patch-status {
description
"A grouping that contains a YANG container
representing the syntax and semantics of
YANG Patch status response message.";
container yang-patch-status {
description
"A container representing the response message
sent by the server after a YANG Patch edit
request message has been processed.";
leaf patch-id {
type string;
description
"The patch-id value used in the request";
}
choice global-status {
description
"Report global errors or complete success.
If there is no case selected then errors
are reported in the edit-status container.";
case global-errors {
uses rc:errors;
description
"This container will be present if global
errors unrelated to a specific edit occurred.";
}
leaf ok {
type empty;
description
"This leaf will be present if the request succeeded
and there are no errors reported in the edit-status
container.";
}
}
container edit-status {
description
"This container will be present if there are
edit-specific status responses to report.
If all edits succeeded and the 'global-status'
returned is 'ok', then a server MAY omit this
container";
list edit {
key edit-id;
description
"Represents a list of status responses,
corresponding to edits in the YANG Patch
request message. If an edit entry was
skipped or not reached by the server,
then this list will not contain a corresponding
entry for that edit.";
leaf edit-id {
type string;
description
"Response status is for the edit list entry
with this edit-id value.";
}
choice edit-status-choice {
description
"A choice between different types of status
responses for each edit entry.";
leaf ok {
type empty;
description
"This edit entry was invoked without any
errors detected by the server associated
with this edit.";
}
case errors {
uses rc:errors;
description
"The server detected errors associated with the
edit identified by the same edit-id value.";
}
}
}
}
}
} // grouping yang-patch-status
}
<CODE ENDS>
This document registers one URI in the IETF XML registry [RFC3688]. Following the format in RFC 3688, the following registration is requested to be made.
URI: urn:ietf:params:xml:ns:yang:ietf-yang-patch
Registrant Contact: The NETMOD WG of the IETF.
XML: N/A, the requested URI is an XML namespace.
This document registers one YANG module in the YANG Module Names registry [RFC6020].
name: ietf-yang-patch namespace: urn:ietf:params:xml:ns:yang:ietf-yang-patch prefix: ypatch // RFC Ed.: replace XXXX with RFC number and remove this note reference: RFC XXXX
The MIME media type for a YANG Patch document is application/yang.patch.
Type name: application Subtype name: yang.patch Required parameters: none Optional parameters: none Encoding considerations: 8-bit Security considerations: See Section 5 of RFC XXXX Interoperability considerations: none // RFC Ed.: replace XXXX with RFC number and remove this note Published specification: RFC XXXX
The MIME media type for a YANG Patch status document is application/yang.patch-status.
Type name: application Subtype name: yang.patch-status Required parameters: none Optional parameters: none Encoding considerations: 8-bit Security considerations: See Section 5 of RFC XXXX Interoperability considerations: none // RFC Ed.: replace XXXX with RFC number and remove this note Published specification: RFC XXXX
This document registers one capability identifier in "RESTCONF Protocol Capability URNs" registry
Index
Capability Identifier
------------------------
:yang-patch
urn:ietf:params:restconf:capability:yang-patch:1.0
The YANG Patch media type does not introduce any significant new security threats, beyond what is described in [I-D.ietf-netconf-restconf]. This document defines edit processing instructions for a variant of the PATCH method, as used within the RESTCONF protocol.
It is important for server implementations to carefully validate all the edit request parameters in some manner. If the entire YANG Patch request cannot be completed, then no configuration changes to the system are done.
A server implementation SHOULD attempt to prevent system disruption due to partial processing of the YANG Patch edit list. It may be possible to construct an attack on such a server, which relies on the edit processing order mandated by YANG Patch.
The authors would like to thank the following people for their contributions to this document: Rex Fernando.
-- RFC Ed.: remove this section before publication.
The YANG Patch issue tracker can be found here: https://github.com/netconf-wg/yang-patch/issues
-- RFC Ed.: remove this section before publication.
Refer to the github issue tracker for any open issues:
https://github.com/netconf-wg/yang-patch/issues
The example YANG module used in this document represents a simple media jukebox interface. The "example‑jukebox" YANG module is defined in [I-D.ietf-netconf-restconf].
YANG Tree Diagram for "example‑jukebox" Module:
+--rw jukebox!
+--rw library
| +--rw artist* [name]
| | +--rw name string
| | +--rw album* [name]
| | +--rw name string
| | +--rw genre? identityref
| | +--rw year? uint16
| | +--rw admin
| | | +--rw label? string
| | | +--rw catalogue-number? string
| | +--rw song* [name]
| | +--rw name string
| | +--rw location string
| | +--rw format? string
| | +--rw length? uint32
| +--ro artist-count? uint32
| +--ro album-count? uint32
| +--ro song-count? uint32
+--rw playlist* [name]
| +--rw name string
| +--rw description? string
| +--rw song* [index]
| +--rw index uint32
| +--rw id leafref
+--rw player
+--rw gap? decimal64
rpcs:
+---x play
+--ro input
+--ro playlist string
+--ro song-number uint32
This section includes RESTCONF examples. Most examples are shown in JSON encoding [RFC7158], and some are shown in XML encoding [W3C.REC-xml-20081126].
The following example shows several songs being added to an existing album. Each edit contains one song. The first song already exists, so an error will be reported for that edit. The rest of the edits were not attempted, since the first edit failed.
Request from client:
PATCH /restconf/data/example-jukebox:jukebox/
library/artist=Foo%20Fighters/album=Wasting%20Light HTTP/1.1
Host: example.com
Accept: application/yang.patch-status+json
Content-Type: application/yang.patch+json
{
"ietf-yang-patch:yang-patch" : {
"patch-id" : "add-songs-patch",
"edit" : [
{
"edit-id" : "edit1",
"operation" : "create",
"target" : "/song",
"value" : {
"song" : {
"name" : "Bridge Burning",
"location" : "/media/bridge_burning.mp3",
"format" : "MP3",
"length" : 288
}
}
},
{
"edit-id" : "edit2",
"operation" : "create",
"target" : "/song",
"value" : {
"song" : {
"name" : "Rope",
"location" : "/media/rope.mp3",
"format" : "MP3",
"length" : 259
}
}
},
{
"edit-id" : "edit3",
"operation" : "create",
"target" : "/song",
"value" : {
"song" : {
"name" : "Dear Rosemary",
"location" : "/media/dear_rosemary.mp3",
"format" : "MP3",
"length" : 269
}
}
}
]
}
}
Response from server:
HTTP/1.1 409 Conflict
Date: Mon, 23 Apr 2012 13:01:20 GMT
Server: example-server
Last-Modified: Mon, 23 Apr 2012 13:01:20 GMT
Content-Type: application/yang.patch-status+json
{
"ietf-yang-patch:yang-patch-status" : {
"patch-id" : "add-songs-patch",
"edit-status" : {
"edit" : [
{
"edit-id" : "edit1",
"errors" : {
"error" : [
{
"error-type": "application",
"error-tag": "data-exists",
"error-path": "/example-jukebox:jukebox/library
/artist=Foo%20Fighters/album=Wasting%20Light
/song=Burning%20Light",
"error-message":
"Data already exists, cannot be created"
}
]
}
}
]
}
}
}
The following example shows several songs being added to an existing album.
Request from client:
PATCH /restconf/data/example-jukebox:jukebox/
library/artist=Foo%20Fighters/album=Wasting%20Light
HTTP/1.1
Host: example.com
Accept: application/yang.patch-status+json
Content-Type: application/yang.patch+json
{
"ietf-yang-patch:yang-patch" : {
"patch-id" : "add-songs-patch-2",
"edit" : [
{
"edit-id" : "edit1",
"operation" : "create",
"target" : "/song",
"value" : {
"song" : {
"name" : "Rope",
"location" : "/media/rope.mp3",
"format" : "MP3",
"length" : 259
}
}
},
{
"edit-id" : "edit2",
"operation" : "create",
"target" : "/song",
"value" : {
"song" : {
"name" : "Dear Rosemary",
"location" : "/media/dear_rosemary.mp3",
"format" : "MP3",
"length" : 269
}
}
}
]
}
}
Response from server:
HTTP/1.1 200 Success
Date: Mon, 23 Apr 2012 13:01:20 GMT
Server: example-server
Last-Modified: Mon, 23 Apr 2012 13:01:20 GMT
Content-Type: application/yang.patch-status+json
{
"ietf-yang-patch:yang-patch-status" : {
"patch-id" : "add-songs-patch-2",
"ok" : [null]
}
}
The following example shows a song being moved within an existing playlist. Song "1" in playlist "Foo‑One" is being moved after song "3" in the playlist. The operation succeeds, so a non-error reply example can be shown.
Request from client:
PATCH /restconf/data/example-jukebox:jukebox/
playlist=Foo-One HTTP/1.1
Host: example.com
Accept: application/yang.patch-status+json
Content-Type: application/yang.patch+json
{
"ietf-yang-patch:yang-patch" : {
"patch-id" : "move-song-patch",
"comment" : "Move song 1 after song 3",
"edit" : [
{
"edit-id" : "edit1",
"operation" : "move",
"target" : "/song/1",
"point" : "/song3",
"where" : "after"
}
]
}
}
Response from server:
HTTP/1.1 400 OK
Date: Mon, 23 Apr 2012 13:01:20 GMT
Server: example-server
Last-Modified: Mon, 23 Apr 2012 13:01:20 GMT
Content-Type: application/yang.patch-status+json
{
"ietf-restconf:yang-patch-status" : {
"patch-id" : "move-song-patch",
"ok" : [null]
}
}