draft-ietf-netconf-restconf-trace-ctx-headers.txt

NETCONF                                                      R. Gagliano
Internet-Draft                                             Cisco Systems
Intended status: Standards Track                              K. Larsson
Expires: 9 January 2025                              Deutsche Telekom AG
                                                             J. Lindblad
                                                           Cisco Systems
                                                             8 July 2024


          RESTCONF Extension to support Trace Context Headers
          draft-ietf-netconf-restconf-trace-ctx-headers-latest

Abstract

   This document extends the RESTCONF protocol in order to support trace
   context propagation as defined by the W3C.

About This Document

   This note is to be removed before publishing as an RFC.

   The latest revision of this draft can be found at https://github.com/
   netconf-wg/restconf-trace-ctx-headers/blob/gh-pages/draft-ietf-
   netconf-restconf-trace-ctx-headers.txt.  Status information for this
   document may be found at https://datatracker.ietf.org/doc/draft-ietf-
   netconf-restconf-trace-ctx-headers/.

   Discussion of this document takes place on the NETCONF Working Group
   mailing list (mailto:netconf@ietf.org), which is archived at
   https://mailarchive.ietf.org/arch/browse/netconf/.  Subscribe at
   https://www.ietf.org/mailman/listinfo/netconf/.

   Source for this draft and an issue tracker can be found at
   https://github.com/netconf-wg/restconf-trace-ctx-headers.

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

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   This Internet-Draft will expire on 9 January 2025.

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Table of Contents

   1.  Introduction
     1.1.  Terminology
   2.  RESTCONF Extensions
     2.1.  Error Handling
     2.2.  Trace Context header versionning
   3.  Security Considerations
   4.  IANA Considerations
   5.  Acknowledgments
   6.  References
     6.1.  Normative References
     6.2.  Informative References
   Appendix A.  Example RESTCONF calls
     A.1.  Successful creation New Data Resources (from section B.2.1
           in RFC8040)
     A.2.  Unsuccessful creation New Data Resources (from section
           B.2.1 in RFC8040)
   Appendix B.  Changes (to be deleted by RFC Editor)
     B.1.  From version 00 to -01
     B.2.  From version 00 to
           draft-ietf-netconf-restconf-trace-ctx-headers-00
   Authors' Addresses

1.  Introduction

   Network automation and management systems commonly consist of
   multiple sub-systems and together with the network devices they
   manage, they effectively form a distributed system.  Distributed
   tracing is a methodology implemented by tracing tools to follow,
   analyze and debug operations, such as configuration transactions,
   across multiple distributed systems.  An operation is uniquely
   identified by a trace-id and through a trace context, carries some
   metadata about the operation.  Propagating this "trace context"
   between systems enables forming a coherent view of the entire
   operation as carried out by all involved systems.

   The W3C has defined two HTTP headers (_traceparent_ and _tracestate_)
   for context propagation that are useful for distributed systems like
   the ones defined in [RFC8309].  The goal of this document is to adopt
   this W3C specification for the RESTCONF protocol.

   This document does not define new HTTP extensions but makes those
   defined in [W3C-Trace-Context] optional headers for the RESTCONF
   protocol.

   In [I-D.draft-ietf-netconf-trace-ctx-extension-01], the NETCONF
   protocol extension is defined and we will re-use several of the YANG
   and XML objects defined in that document for RESTCONF.  Please refer
   to that document for additional context and example applications.

1.1.  Terminology

   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.

2.  RESTCONF Extensions

   A RESTCONF server MUST support the trace context _traceparent_ header
   as defined in [W3C-Trace-Context].

   A RESTCONF server SHOULD support the trace context _tracestate_
   header as defined in [W3C-Trace-Context].

2.1.  Error Handling

   The RESTCONF server SHOULD follow the "Processing Model for Working
   with Trace Context" as specified in [W3C-Trace-Context].  Based on
   this processing model, it is NOT RECOMMENDED to reject an RPC because
   of the trace context header values.

   If the server still decides to reject the RPC because of the trace
   context header values, the server MUST return a RESTCONF rpc-error
   with the following values:

     error-tag:      operation-failed
     error-type:     protocol
     error-severity: error

   Additionally, the error-info tag MUST contain relevant details about
   the error in the form of an sx:structure otlp-trace-context-error-
   info defined in ietf-netconf-otlp-context.yang from
   [I-D.draft-ietf-netconf-trace-ctx-extension-01].

2.2.  Trace Context header versionning

   This extension refers to the [W3C-Trace-Context] trace context
   capability.  The W3C _traceparent_ and _tracestate_ headers include
   the notion of versions.  It would be desirable for a RESTCONF client
   to be able to discover the one or multiple versions of these headers
   supported by a server.  We would like to achieve this goal avoiding
   the definition of new RESTCONF capabilities for each headers'
   version.

   [I-D.draft-ietf-netconf-trace-ctx-extension-01] defines a pair of
   YANG modules that MUST be included in the YANG library per [RFC8525]
   of the RESTCONF server supporting the RESTCONF Trace Context
   extension that will refer to the headers' supported versions.  Future
   updates of this document could include additional YANG modules for
   new headers' versions.

3.  Security Considerations

   There are two YANG modules specified in this document.  These modules
   are completely empty, and therefore have very limited security
   considerations.  Their purpose is only to indicate which trace
   context header versions the server supports using YANG Library
   [RFC8525].

   Even though both YANG modules are empty, there are still some
   security considerations worth mentioning, however.  This is because
   the functionality described in this document is in the form of
   additional HTTP headers (which cannot be described using YANG)
   relating to the network management protocol RESTCONF [RFC8040].

   The _traceparent_ and _tracestate_ headers make it easier to track
   the flow of requests and their downstream effect on other systems.
   This is indeed the whole point with these headers.  This knowledge
   could also be of use to bad actors that are working to build a map of
   the managed network.

   All advice mentioned in the [W3C-Trace-Context] under the Privacy
   Considerations and Security Considerations also apply to this
   document.

   The lowest RESTCONF layer is HTTPS, and the mandatory-to-implement
   secure transport is TLS [RFC8446].

   The Network Configuration Access Control Model (NACM) [RFC8341]
   provides the means to restrict access for particular NETCONF or
   RESTCONF users to a preconfigured subset of all available NETCONF or
   RESTCONF protocol operations and content.

4.  IANA Considerations

   This document has no IANA actions.

5.  Acknowledgments

   The authors would like to acknowledge the valuable implementation
   feedback from Christian Rennerskog and Per Andersson.  Many thanks to
   Raul Rivas Felix, Alexander Stoklasa, Luca Relandini and Erwin
   Vrolijk for their help with the demos regarding integrations.  The
   help and support from Jean Quilbeuf and Benoît Claise has also been
   invaluable to this work.

6.  References

6.1.  Normative References

   [I-D.draft-ietf-netconf-trace-ctx-extension-01]
              Gagliano, R., Larsson, K., and J. Lindblad, "NETCONF
              Extension to support Trace Context propagation", Work in
              Progress, Internet-Draft, draft-ietf-netconf-trace-ctx-
              extension-01, 8 July 2024,
              <https://datatracker.ietf.org/doc/html/draft-ietf-netconf-
              trace-ctx-extension-01>.

   [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/rfc/rfc2119>.

   [RFC8040]  Bierman, A., Bjorklund, M., and K. Watsen, "RESTCONF
              Protocol", RFC 8040, DOI 10.17487/RFC8040, January 2017,
              <https://www.rfc-editor.org/rfc/rfc8040>.

   [RFC8174]  Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
              2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
              May 2017, <https://www.rfc-editor.org/rfc/rfc8174>.

   [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/rfc/rfc8341>.

   [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/rfc/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/rfc/rfc8525>.

   [W3C-Trace-Context]
              "W3C Recommendation on Trace Context", 23 November 2021,
              <https://www.w3.org/TR/2021/REC-trace-context-
              1-20211123/>.

6.2.  Informative References

   [RFC8309]  Wu, Q., Liu, W., and A. Farrel, "Service Models
              Explained", RFC 8309, DOI 10.17487/RFC8309, January 2018,
              <https://www.rfc-editor.org/rfc/rfc8309>.

Appendix A.  Example RESTCONF calls

   All examples from [RFC8040] Appendix B could be recreated in this
   seciton by adding the new header described in this document.  We
   selected one example from that document as reference.

A.1.  Successful creation New Data Resources (from section B.2.1 in
      [RFC8040])

   To create a new "artist" resource within the "library" resource, the
   client might send the following request:

    POST /restconf/data/example-jukebox:jukebox/library HTTP/1.1
    Host: example.com
    Content-Type: application/yang-data+json
    traceparent: 00-405062f633be64ee006089dfca95a153-e021f9e263aad8e2-01
    tracestate: vendorname1=opaqueValue1,vendorname2=opaqueValue2

    {
      "example-jukebox:artist" : [
        {
          "name" : "Foo Fighters"
        }
      ]
    }

   If the resource is created, the server might respond as follows:

    HTTP/1.1 201 Created
    Date: Thu, 26 Jan 2017 20:56:30 GMT
    Server: example-server
    Location: https://example.com/restconf/data/\
        example-jukebox:jukebox/library/artist=Foo%20Fighters
    Last-Modified: Thu, 26 Jan 2017 20:56:30 GMT
    ETag: "b3830f23a4c"
    traceparent: 00-405062f633be64ee006089dfca95a153-e021f9e263aad8e2-01
    tracestate: vendorname1=opaqueValue1,vendorname2=opaqueValue2

A.2.  Unsuccessful creation New Data Resources (from section B.2.1 in
      [RFC8040])

   [W3C-Trace-Context] specifies that vendor MAY validate the
   _tracestate_ header and that invalid headers MAY be discarded.  In
   the section about Error handling (Section 2.1), it is stated that
   servers MAY return an error.  Let's assume that is our
   implementation.

   Example of a badly formated _tracestate_ header using [RFC8040]
   example B.2.1, which by following :

    POST /restconf/data/example-jukebox:jukebox/library HTTP/1.1
    Host: example.com
    Content-Type: application/yang-data+json
    traceparent: 00-405062f633be64ee006089dfca95a153-e021f9e263aad8e2-01
    tracestate: SomeBadFormatHere

    {
      "example-jukebox:artist" : [
        {
          "name" : "Foo Fighters"
        }
      ]
    }

   And the expected error message:

    HTTP/1.1 400 Bad Request
    Date: Tue, 20 Jun 2023 20:56:30 GMT
    Server: example-server
    Content-Type: application/yang-data+json

    { "ietf-restconf:errors" : {
        "error" : [
          {
            "error-type" : "protocol",
            "error-tag" : "operation-failed",
            "error-severity" : "error",
            "error-message" :
              "OTLP traceparent attribute incorrectly formatted",
            "error-info": {
              "ietf-netconf-otlp-context:meta-name" : "tracestate",
              "ietf-netconf-otlp-context:meta-value" :
                "SomeBadFormatHere",
              "ietf-netconf-otlp-context:error-type" :
                "ietf-netconf-otlp-context:bad-format"
            }
          }
        ]
      }
    }

Appendix B.  Changes (to be deleted by RFC Editor)

B.1.  From version 00 to -01

   *  Added Security considerations

   *  Added Acknowledgements

   *  Added several Normative references

   *  Added links to latest document on github

   *  Added RESTCONF example for success and error

   *  Modified Error Handling to reflect better W3C alignment based on
      implementation feedback

   *  Firmed up error handling and YANG-library to MUST-requirements

B.2.  From version 00 to draft-ietf-netconf-restconf-trace-ctx-
      headers-00

   *  Adopted by NETCONF WG

   *  Moved repository to NETCONF WG

   *  Changed build system to use martinthomson's excellent framework

   *  Ran make fix-lint to remove white space at EOL etc.

   *  Added this change note.  No other content changes

Authors' Addresses

   Roque Gagliano
   Cisco Systems
   Avenue des Uttins 5
   CH-1180 Rolle
   Switzerland
   Email: rogaglia@cisco.com


   Kristian Larsson
   Deutsche Telekom AG
   Email: kll@dev.terastrm.net


   Jan Lindblad
   Cisco Systems
   Email: jlindbla@cisco.com