]> Cisco Systems

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Deutsche Telekom AG

kll@dev.terastrm.net

Cisco Systems

jlindbla@cisco.com

Operations and Management NETCONF telemetry distributed systems opentelemetry This document extends the RESTCONF protocol in order to support trace context propagation as defined by the W3C. About This Document The latest revision of this draft can be found at . Status information for this document may be found at . Discussion of this document takes place on the NETCONF Working Group mailing list (), which is archived at . Subscribe at . Source for this draft and an issue tracker can be found at .

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 . 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 optional headers for the RESTCONF protocol. In , 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.

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 when, and only when, they appear in all capitals, as shown here.

RESTCONF Extensions A RESTCONF server SHOULD support trace context traceparent header as defined in . A RESTCONF server SHOULD support trace context tracestate header as defined in .

Errors handling The RESTCONF server SHOULD follow the "Processing Model for Working with Trace Context" as specified in . If the server rejects the RPC because of the trace context headers values, the server MUST return an rpc-error with the following values: Additionally, the error-info tag SHOULD contain a relevant details about the error. Finally, the sx:structure defined in SHOULD be present in any error message from the server. Example of a badly formated trace context extension using example B.2.1: And the expected error message:

Trace Context header versionning This extension refers to the trace context capability. The W3C traceparent and trace-state 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 deffinition of new RESTCONF capabilities for each headers' version. defines a pair YANG modules that SHOULD be included in the YANG library per 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.

Security Considerations TODO Security

IANA Considerations This document has no IANA actions.

Acknowledgments We would like to acknowledge

References Normative References In many standards track documents several words are used to signify the requirements in the specification. These words are often capitalized. This document defines these words as they should be interpreted in IETF documents. This document specifies an Internet Best Current Practices for the Internet Community, and requests discussion and suggestions for improvements. RFC 2119 specifies common key words that may be used in protocol specifications. This document aims to reduce the ambiguity by clarifying that only UPPERCASE usage of the key words have the defined special meanings. This document describes a YANG library that provides information about the YANG modules, datastores, and datastore schemas used by a network management server. Simple caching mechanisms are provided to allow clients to minimize retrieval of this information. This version of the YANG library supports the Network Management Datastore Architecture (NMDA) by listing all datastores supported by a network management server and the schema that is used by each of these datastores. This document describes an HTTP-based protocol that provides a programmatic interface for accessing data defined in YANG, using the datastore concepts defined in the Network Configuration Protocol (NETCONF). Cisco Systems Deutsche Telekom AG Cisco Systems This document defines how to propagate trace context information across the Network Configuration Protocol (NETCONF), that enables distributed tracing scenarios. It is an adaption of the HTTP-based W3C specification. Informative References The IETF has produced many modules in the YANG modeling language. The majority of these modules are used to construct data models to model devices or monolithic functions. A small number of YANG modules have been defined to model services (for example, the Layer 3 Virtual Private Network Service Model (L3SM) produced by the L3SM working group and documented in RFC 8049). This document describes service models as used within the IETF and also shows where a service model might fit into a software-defined networking architecture. Note that service models do not make any assumption of how a service is actually engineered and delivered for a customer; details of how network protocols and devices are engineered to deliver a service are captured in other modules that are not exposed through the interface between the customer and the provider.

Example RESTCONF calls TBD

Changes (to be deleted by RFC Editor)

From version 00 to draft-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.

TO DO List (to be deleted by RFC Editor)

• Security Considerations
• Example RESTCONF Calls
• The W3C is working on a draft document to introduce the concept of "baggage" that we expect part of a future draft for NETCONF and RESTCONF