| Network Working Group | A. Bierman |
| Internet-Draft | YumaWorks |
| Intended status: Standards Track | M. Bjorklund |
| Expires: May 14, 2017 | Tail-f Systems |
| K. Watsen | |
| Juniper Networks | |
| November 10, 2016 |
YANG Patch Media Type
draft-ietf-netconf-yang-patch-13
This document describes a method for applying patches to configuration 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 May 14, 2017.
Copyright (c) 2016 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 datastores defined in [RFC6241], which contain conceptual data that conforms to schema specified with YANG [RFC7950]. An "ordered edit list" approach is needed to provide RESTCONF client developers with more precise RESTCONF client control of the edit procedure than existing mechanisms found in [I-D.ietf-netconf-restconf].
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]. This document only specifies the use of the YANG Patch media type with the RESTCONF protocol.
It may be possible to use YANG Patch with other protocols besides RESTCONF. This is outside the scope of this document. For any protocol which supports the YANG Patch media type, if the entire patch document cannot be successfully applied, then the server MUST NOT apply any of the changes. It may be possible to use YANG Patch with datastore types other than a configuration datastore. This is outside the scope of this document.
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in [RFC2119].
The following terms are defined in [RFC6241]:
The following terms are defined in [RFC7230]:
The following terms are defined in [RFC7231]:
The following terms are defined in [RFC7950]:
The following terms are defined in [I-D.ietf-netconf-restconf]:
The following terms are used within this document:
Some protocol message lines within examples throughout the document are split into multiple lines for display purposes only. When a line ends with backslash ('\') as the last character, the line is wrapped for display purposes. It is to be considered to be joined to the next line by deleting the backslash, the following line break, and the leading whitespace of the next line.
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 RESTCONF server. The specific fields are defined in the YANG module in Section 3.
The YANG Patch operation is invoked by the RESTCONF client by sending a PATCH method request with a representation using either the "application/yang‑patch+xml" or "application/yang‑patch+json" media type. This message-body representing the YANG Patch input parameters MUST be present.
YANG Patch has some features that are not possible with the PATCH method in RESTCONF:
The YANG Patch "patch‑id" may be useful for debugging, and SHOULD be present in any audit audit logging records generated by the RESTCONF server for a patch.
The RESTCONF server MUST return the Accept-Patch header field in an OPTIONS response, as specified in [RFC5789], which includes the media type for YANG Patch. This is needed by a client to determine the message encoding formats supported by the server (e.g., XML, JSON, or both). An example is shown in Figure 1.
Accept-Patch: application/yang-patch+xml,application/yang-patch+json
Figure 1: Example Accept-Patch header
Note that YANG Patch can only edit data resources. The PATCH method cannot be used to replace the datastore resource. Although the "ietf‑yang‑patch" YANG module is written using YANG version 1.1 [RFC7950], an implementation of YANG Patch can be used with content defined in YANG version 1 [RFC6020] as well.
A YANG Patch can be encoded in XML format according to [W3C.REC-xml-20081126]. It can also be encoded in JSON, according to "JSON Encoding of Data Modeled with YANG" [RFC7951]. If any meta-data needs to be sent in a JSON message, it is encoded according to "Defining and Using Metadata with YANG" [RFC7952].
The YANG Patch operation uses the RESTCONF target resource URI to identify the resource that will be patched. This can be the datastore resource itself, i.e., "{+restconf}/data", to edit top-level configuration data resources, or it can be a configuration data resource within the datastore resource, e.g., "{+restconf}/data/ietf‑interfaces:interfaces", to edit sub-resources within a top-level configuration data resource.
The target resource MUST identify exactly one resource instance. If more than one resource instance is identified, then the request MUST NOT be processed, and a "400 Bad Request" error response MUST be sent by the server. If the target resource does not identify any existing resource instance then the request MUST NOT be processed, and a "404 Not Found" error response MUST be sent by the server.
Each edit with a YANG Patch identifies a target data node for the associated edit. This is described in Section 2.4.
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.
The merge, replace, create, delete, and remove edit operations have the exact same meaning as defined for the "operation" attribute in section 7.2 of [RFC6241].
Each edit within a YANG Patch MUST identify exactly one data resource instance. If an edit represents more than one resource instance, then the request MUST NOT be processed, and a "400 Bad Request" error response MUST be sent by the server. If the edit does not identify any existing resource instance, and the operation for the edit is not "create", then the request MUST NOT be processed, and a "404 Not Found" error response MUST be sent by the server. A "yang‑patch‑status" response MUST be sent by the server identifying the edit(s) that are not valid.
YANG Patch does not provide any access to specific datastores. It is an implementation detail how a server processes an edit if it is co-located with a NETCONF server that does provide access to individual datastores. A complete datastore cannot be replaced in the same manner as provided by the "copy‑config" operation defined in section 7.3 of [RFC6241]. Only the specified nodes in a YANG Patch are affected.
A message-body representing the YANG Patch is sent by the RESTCONF 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
+---- yang-patch
+---- patch-id string
+---- comment? string
+---- edit* [edit-id]
+---- edit-id string
+---- operation enumeration
+---- target target-resource-offset
+---- point? target-resource-offset
+---- where? enumeration
+---- value?
A message-body representing the YANG Patch Status is returned to the RESTCONF 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:
+---- yang-patch-status
+---- patch-id string
+---- (global-status)?
| +--:(global-errors)
| | +---- errors
| | +---- error*
| | +---- error-type enumeration
| | +---- error-tag string
| | +---- error-app-tag? string
| | +---- error-path? instance-identifier
| | +---- error-message? string
| | +---- error-info?
| +--:(ok)
| +---- ok? empty
+---- edit-status
+---- edit* [edit-id]
+---- edit-id string
+---- (edit-status-choice)?
+--:(ok)
| +---- ok? empty
+--:(errors)
+---- errors
+---- error*
+---- error-type enumeration
+---- error-tag string
+---- error-app-tag? string
+---- error-path? instance-identifier
+---- error-message? string
+---- error-info?
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 treated as an absolute path expression identifying the target data node for the corresponding edit. The first node specified in the "target" leaf is a top-level data node defined within a YANG module. The "target" leaf MUST NOT contain a single forward slash "/", since this would identify the datastore resource, not a data resource.
If the target resource specified in the request URI identifies a configuration data resource, then the path string in the "target" leaf is treated as a relative path expression. The first node specified in the "target" leaf is a child configuration data node of the data node associated with the target resource. If the "target" leaf contains a single forward slash "/", then the target data node is the target resource data node.
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 |
If a YANG Patch is completed without errors, the RESTCONF server MUST return a "yang‑patch‑status" message with a global-status choice set to 'ok'.
The RESTCONF server will save the running datastore to non-volatile storage if it supports non-volatile storage, and if the running datastore contents have changed, as specified in [I-D.ietf-netconf-restconf].
Refer to Appendix D.1.2 for a example of a successful YANG Patch response.
If a well-formed, schema-valid YANG Patch message is received, then the RESTCONF server will process the supplied edits in ascending order. The following error modes apply to the processing of this edit list:
If a YANG Patch is completed with errors, the RESTCONF server SHOULD return a "yang‑patch‑status" message. It is possible (e.g., within a distributed implementation), that an invalid request will be rejected before the YANG patch edits are processed. In this case, the server MUST send the appropriate HTTP error response instead.
Refer to Appendix D.1.1 for a example of an error YANG Patch response.
A URI is defined to identify the YANG Patch extension to the base RESTCONF protocol. If the RESTCONF server supports the YANG Patch media type, then the "yang‑patch" RESTCONF capability defined in Section 4.3 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 'yang‑data' extension statements, which are not meant to be implemented as datastore contents by a RESTCONF server.
The "ietf‑restconf" module from [I-D.ietf-netconf-restconf] is used by this module for the 'yang‑data' extension definition.
RFC Ed.: update the date below with the date of RFC publication and remove this note.
<CODE BEGINS> file "ietf-yang-patch@2016-11-09.yang"
module ietf-yang-patch {
yang-version 1.1;
namespace "urn:ietf:params:xml:ns:yang:ietf-yang-patch";
prefix "ypatch";
import ietf-restconf { prefix rc; }
organization
"IETF NETCONF (Network Configuration) Working Group";
contact
"WG Web: <http://tools.ietf.org/wg/netconf/>
WG List: <mailto:netconf@ietf.org>
Author: Andy Bierman
<mailto:andy@yumaworks.com>
Author: Martin Bjorklund
<mailto:mbj@tail-f.com>
Author: 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) 2016 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-13.txt
// RFC Ed.: update the date below with the date of RFC publication
// and remove this note.
revision 2016-11-09 {
description
"Initial revision.";
reference
"RFC XXXX: YANG Patch Media Type.";
}
typedef target-resource-offset {
type string;
description
"Contains a data resource identifier string representing
a sub-resource within the target resource.
The document root for this expression is the
target resource that is specified in the
protocol operation (e.g., the URI for the PATCH request).
This string is encoded according the same rules as
a data resource identifier in a RESTCONF Request URI.";
// RFC Ed.: replace "draft-ietf-netconf-restconf" below
// with RFC XXXX, where XXXX is the number of the RESTCONF RFC,
// and remove this note.
reference
"draft-ietf-netconf-restconf, section 3.5.3";
}
rc:yang-data "yang-patch" {
uses yang-patch;
}
rc:yang-data "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 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 7950, section 8.3.";
leaf patch-id {
type string;
mandatory true;
description
"An arbitrary string provided by the client to identify
the entire patch. Error messages returned by the server
pertaining to this patch will be identified by this
patch-id value. A client SHOULD attempt to generate
unique patch-id values to distinguish between transactions
from multiple clients in any audit logs maintained
by the server.";
}
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. The
'target' leaf identifies the data node to be created,
not the parent data node.";
}
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 node for the edit
operation. If the target has the value '/', then
the target data node is the target resource.
The target node MUST identify a data resource,
not the datastore resource.";
}
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.";
}
anydata 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 anydata 'value'
contains 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 contains 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.
If there was no patch-id present in the request
then this field will not be present.";
}
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 that are 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 as a namespace 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 NETCONF 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
Type name: application
Subtype name: yang-patch+xml
Required parameters: None
Optional parameters: None
// RFC Ed.: replace 'XXXX' with the real RFC number,
// and remove this note
Encoding considerations: 8-bit
Each conceptual YANG data node is encoded according to the
XML Encoding Rules and Canonical Format for the specific
YANG data node type defined in [RFC7950].
In addition, the "yang-patch" YANG Patch template found
in [RFCXXXX] defines the structure of a YANG Patch request.
// RFC Ed.: replace 'NN' in Section NN of [RFCXXXX] with the
// section number for Security Considerations
// Replace 'XXXX' in Section NN of [RFCXXXX] with the actual
// RFC number, and remove this note.
Security considerations: Security considerations related
to the generation and consumption of RESTCONF messages
are discussed in Section NN of [RFCXXXX].
Additional security considerations are specific to the
semantics of particular YANG data models. Each YANG module
is expected to specify security considerations for the
YANG data defined in that module.
// RFC Ed.: replace XXXX with actual RFC number and remove this
// note.
Interoperability considerations: [RFCXXXX] specifies the format
of conforming messages and the interpretation thereof.
// RFC Ed.: replace XXXX with actual RFC number and remove this
// note.
Published specification: RFC XXXX
Applications that use this media type: Instance document
data parsers used within a protocol or automation tool
that utilize the YANG Patch data structure.
Fragment identifier considerations: Same as for application/xml
Additional information:
Deprecated alias names for this type: N/A
Magic number(s): N/A
File extension(s): None
Macintosh file type code(s): "TEXT"
// RFC Ed.: replace XXXX with actual RFC number and remove this
// note.
Person & email address to contact for further information: See
Authors' Addresses section of [RFCXXXX].
Intended usage: COMMON
Restrictions on usage: N/A
// RFC Ed.: replace XXXX with actual RFC number and remove this
// note.
Author: See Authors' Addresses section of [RFCXXXX].
Change controller: Internet Engineering Task Force
(mailto:iesg&ietf.org).
Provisional registration? (standards tree only): no
Type name: application
Subtype name: yang-patch+json
Required parameters: None
Optional parameters: None
// RFC Ed.: replace draft-ietf-netmod-yang-json with
// the actual RFC reference for JSON Encoding of YANG Data,
// and remove this note.
// RFC Ed.: replace draft-ietf-netmod-yang-metadata with
// the actual RFC reference for JSON Encoding of YANG Data,
// and remove this note.
// RFC Ed.: replace 'XXXX' with the real RFC number,
// and remove this note
Encoding considerations: 8-bit
Each conceptual YANG data node is encoded according to
[draft-ietf-netmod-yang-json]. A data annotation is
encoded according to [draft-ietf-netmod-yang-metadata]
In addition, the "yang-patch" YANG Patch template found
in [RFCXXXX] defines the structure of a YANG Patch request.
// RFC Ed.: replace 'NN' in Section NN of [RFCXXXX] with the
// section number for Security Considerations
// Replace 'XXXX' in Section NN of [RFCXXXX] with the actual
// RFC number, and remove this note.
Security considerations: Security considerations related
to the generation and consumption of RESTCONF messages
are discussed in Section NN of [RFCXXXX].
Additional security considerations are specific to the
semantics of particular YANG data models. Each YANG module
is expected to specify security considerations for the
YANG data defined in that module.
// RFC Ed.: replace XXXX with actual RFC number and remove this
// note.
Interoperability considerations: [RFCXXXX] specifies the format
of conforming messages and the interpretation thereof.
// RFC Ed.: replace XXXX with actual RFC number and remove this
// note.
Published specification: RFC XXXX
Applications that use this media type: Instance document
data parsers used within a protocol or automation tool
that utilize the YANG Patch data structure.
Fragment identifier considerations: The syntax and semantics
of fragment identifiers are the same as specified for the
"application/json" media type.
Additional information:
Deprecated alias names for this type: N/A
Magic number(s): N/A
File extension(s): None
Macintosh file type code(s): "TEXT"
// RFC Ed.: replace XXXX with actual RFC number and remove this
// note.
Person & email address to contact for further information: See
Authors' Addresses section of [RFCXXXX].
Intended usage: COMMON
Restrictions on usage: N/A
// RFC Ed.: replace XXXX with actual RFC number and remove this
// note.
Author: See Authors' Addresses section of [RFCXXXX].
Change controller: Internet Engineering Task Force
(mailto:iesg&ietf.org).
Provisional registration? (standards tree only): no
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 may be possible to use YANG Patch with other protocols besides RESTCONF, which is outside the scope of this document.
For RESTCONF, both the client and server MUST be authenticated, according to section 2 of [I-D.ietf-netconf-restconf]. It is important for RESTCONF 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 PATCH request MUST be applied atomically, as specified in section 2 of [RFC5789].
A RESTCONF server implementation SHOULD attempt to prevent system disruption due to incremental processing of the YANG Patch edit list. It may be possible to construct an attack on such a RESTCONF server, which relies on the edit processing order mandated by YANG Patch. A server SHOULD apply only the fully validated configuration to the underlying system. For example, an edit list which deleted an interface and then recreated it could cause system disruption if the edit list was incrementally applied.
A RESTCONF server implementation SHOULD attempt to prevent system disruption due to excessive resource consumption required to fulfill YANG Patch edit requests. It may be possible to construct an attack on such a RESTCONF server, which attempts to consume all available memory or other resource types.
The authors would like to thank the following people for their contributions to this document: Rex Fernando.
Contributions to this material by Andy Bierman are based upon work supported by the The Space & Terrestrial Communications Directorate (S&TCD) under Contract No. W15P7T-13-C-A616. Any opinions, findings and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of The Space & Terrestrial Communications Directorate (S&TCD).
-- 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 [RFC7159], 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. The XML encoding is used in this example.
Request from the RESTCONF client:
PATCH /restconf/data/example-jukebox:jukebox/\
library/artist=Foo%20Fighters/album=Wasting%20Light HTTP/1.1
Host: example.com
Accept: application/yang-data+xml
Content-Type: application/yang-patch+xml
<yang-patch xmlns="urn:ietf:params:xml:ns:yang:ietf-yang-patch">
<patch-id>add-songs-patch</patch-id>
<edit>
<edit-id>edit1</edit-id>
<operation>create</operation>
<target>/song=Bridge%20Burning</target>
<value>
<song xmlns="http://example.com/ns/example-jukebox">
<name>Bridge Burning</name>
<location>/media/bridge_burning.mp3</location>
<format>MP3</format>
<length>288</length>
</song>
</value>
</edit>
<edit>
<edit-id>edit2</edit-id>
<operation>create</operation>
<target>/song=Rope</target>
<value>
<song xmlns="http://example.com/ns/example-jukebox">
<name>Rope</name>
<location>/media/rope.mp3</location>
<format>MP3</format>
<length>259</length>
</song>
</value>
</edit>
<edit>
<edit-id>edit3</edit-id>
<operation>create</operation>
<target>/song=Dear%20Rosemary</target>
<value>
<song xmlns="http://example.com/ns/example-jukebox">
<name>Dear Rosemary</name>
<location>/media/dear_rosemary.mp3</location>
<format>MP3</format>
<length>269</length>
</song>
</value>
</edit>
</yang-patch>
XML Response from the RESTCONF 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-data+xml
<yang-patch-status
xmlns="urn:ietf:params:xml:ns:yang:ietf-yang-patch">
<patch-id>add-songs-patch</patch-id>
<edit-status>
<edit>
<edit-id>edit1</edit-id>
<errors>
<error>
<error-type>application</error-type>
<error-tag>data-exists</error-tag>
<error-path
xmlns:jb="http://example.com/ns/example-jukebox">
/jb:jukebox/jb:library
/jb:artist[jb:name='Foo Fighters']
/jb:album[jb:name='Wasting Light']
/jb:song[jb:name='Burning Light']
</error-path>
<error-message>
Data already exists, cannot be created
</error-message>
</error>
</errors>
</edit>
</edit-status>
</yang-patch-status>
JSON Response from the RESTCONF server:
The following response is shown in JSON format to highlight the difference in the "error‑path" object encoding. For JSON, the instance-identifier encoding in the "JSON Encoding of YANG Data" draft is used.
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-data+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[name='Foo Fighters']\
/album[name='Wasting Light']\
/song[name='Burning Light']",
"error-message":
"Data already exists, cannot be created"
}
]
}
}
]
}
}
}
The following example shows several songs being added to an existing album.
Request from the RESTCONF client:
PATCH /restconf/data/example-jukebox:jukebox/\
library/artist=Foo%20Fighters/album=Wasting%20Light \
HTTP/1.1
Host: example.com
Accept: application/yang-data+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=Rope",
"value" : {
"song" : {
"name" : "Rope",
"location" : "/media/rope.mp3",
"format" : "MP3",
"length" : 259
}
}
},
{
"edit-id" : "edit2",
"operation" : "create",
"target" : "/song=Dear%20Rosemary",
"value" : {
"song" : {
"name" : "Dear Rosemary",
"location" : "/media/dear_rosemary.mp3",
"format" : "MP3",
"length" : 269
}
}
}
]
}
}
Response from the RESTCONF server:
HTTP/1.1 200 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-data+json
{
"ietf-yang-patch:yang-patch-status" : {
"patch-id" : "add-songs-patch-2",
"ok" : [null]
}
}
The following example shows a song being inserted within an existing playlist. Song "6" in playlist "Foo‑One" is being inserted after song "5" in the playlist. The operation succeeds, so a non-error reply example can be shown.
Request from the RESTCONF client:
PATCH /restconf/data/example-jukebox:jukebox/\
playlist=Foo-One HTTP/1.1
Host: example.com
Accept: application/yang-data+json
Content-Type: application/yang-patch+json
{
"ietf-yang-patch:yang-patch" : {
"patch-id" : "move-song-patch",
"comment" : "Insert song 6 after song 5",
"edit" : [
{
"edit-id" : "edit1",
"operation" : "insert",
"target" : "/song=6",
"point" : "/song=5",
"where" : "after",
"value" : {
"example-jukebox:song" : {
"name" : "Dear Prudence",
"location" : "/media/dear_prudence.mp3",
"format" : "MP3",
"length" : 236
}
}
}
]
}
}
Response from the RESTCONF server:
HTTP/1.1 200 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-data+json
{
"ietf-yang-patch:yang-patch-status" : {
"patch-id" : "move-song-patch",
"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. Note that no "value" parameter is needed for a "move" operation. The operation succeeds, so a non-error reply example can be shown.
Request from the RESTCONF client:
PATCH /restconf/data/example-jukebox:jukebox/\
playlist=Foo-One HTTP/1.1
Host: example.com
Accept: application/yang-data+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" : "/song=3",
"where" : "after"
}
]
}
}
Response from the RESTCONF server:
HTTP/1.1 200 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-data+json
{
"ietf-restconf:yang-patch-status" : {
"patch-id" : "move-song-patch",
"ok" : [null]
}
}
The following example shows how 3 top-level data nodes from different modules can be edited at the same time.
Example module "foo" defines leaf X. Example module "bar" defines container Y, with child leafs A and B. Example module "baz" defines list Z, with key C and child leafs D and E.
Request from the RESTCONF client:
PATCH /restconf/data HTTP/1.1
Host: example.com
Accept: application/yang-data+json
Content-Type: application/yang-patch+json
{
"ietf-yang-patch:yang-patch" : {
"patch-id" : "datastore-patch-1",
"comment" : "Edit 3 top-level data nodes at once",
"edit" : [
{
"edit-id" : "edit1",
"operation" : "create",
"target" : "/foo:X",
"value" : {
"foo:X" : 42
}
},
{
"edit-id" : "edit2",
"operation" : "merge",
"target" : "/bar:Y",
"value" : {
"bar:Y" : {
"A" : "test1",
"B" : 99
}
}
},
{
"edit-id" : "edit3",
"operation" : "replace",
"target" : "/baz:Z=2",
"value" : {
"baz:Z" : {
"C" : 2,
"D" : 100,
"E" : false
}
}
}
]
}
}
Response from the RESTCONF server:
HTTP/1.1 200 OK
Date: Mon, 23 Apr 2012 13:02:20 GMT
Server: example-server
Last-Modified: Mon, 23 Apr 2012 13:01:20 GMT
Content-Type: application/yang-data+json
{
"ietf-yang-patch:yang-patch-status" : {
"patch-id" : "datastore-patch-1",
"ok" : [null]
}
}