Internet-Draft 555 HTTP Status Code March 2020
Divilly Expires 21 September 2020 [Page]
Workgroup:
Network Working Group
Internet-Draft:
draft-divilly-status-555-00
Updates:
7231 (if approved)
Published:
Intended Status:
Informational
Expires:
Author:
C. Divilly
Oracle Corporation

User Defined Resource Error HTTP Status Code

Abstract

This document specifies an additional HyperText Transfer Protocol (HTTP) status code to indicate server error conditions arising during evaluation of user defined resources hosted by the server.

Conventions and Terminology

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 RFC 2119 [RFC2119].

Status of This Memo

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 https://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 21 September 2020.

Table of Contents

1. Introduction

Some HTTP servers offer mechanisms for users to define their own programmatically generated resources. This specification terms such a resource as a 'User Defined Resource'. In such cases it may be useful to distinguish between errors arising due to defects in the User Defined Resource and errors arising due to defects in the server itself.

This document proposes a new HTTP status code. This status code indicates that an error occurred when the server attempted to produce a representation of the User Defined Resource, and the error occurred when attempting to evaluate the program that generates the resource, rather than an error condition in the server itself.

2. 555 User Defined Resource Error

The 555 (User Defined Resource Error) status code indicates that the server encountered an unexpected condition when evaluating a User Defined Resource that prevented the server from fulfilling the request.

The response message MAY contain information that identifies the User Defined Resource that originated the error. The response message SHOULD contain additional information that can help the author of User Defined Resource diagnose the root cause of the error.

The response SHOULD include an identifier that uniquely identifies the error condition instance. This identifier should also appear with any log messages or other diagnostic information that the server produces.

The response MAY include a URI [RFC3986] that points to a resource that the User Defined Resource author can use to review the log and other diagnostic information associated with the error condition. Access to this URI MUST be restricted to ensure only the User Defined Resource author can access it.

It is RECOMMENDED that the server provide the User Defined Resource author with secured access to the logs pertaining to the error instance, and a capability to filter/search these logs keyed by the error identifier.

The log information SHOULD provide detailed information about the nature and origin of the error, to enable the User Defined Resource author to diagnose the root cause of the error, whereas the error response SHOULD contain the minimal information required to identify the corresponding log messages.

2.1. Relationship to 500 Internal Server Error

The 555 status code can be considered a specialization of the 500 status code. To quote the HTTP Specification [RFC7231]:

HTTP status codes are extensible. HTTP clients are not required to understand the meaning of all registered status codes, though such understanding is obviously desirable. However, a client MUST understand the class of any status code, as indicated by the first digit, and treat an unrecognized status code as being equivalent to the x00 status code of that class

Thus clients SHOULD treat the 555 status code in the same manner as they treat the 500 status code.

The primary value of the 555 status code is to enable operators of a server to easily distinguish between error conditions arising due to problems in the server itself, and error conditions arising due to problems in a User Defined Resource.

A 500 status is unexpected and likely requires a corrective action from the server operators, as the error may indicate a threat to the stability and availability of the server.

A 555 status is likely to be commonplace, as User Defined Resource authors will be expected to make mistakes when authoring those resources. Assuming a well architected server with proper isolation between the server and the User Defined Resources, such error conditions are unlikely to be a threat to the stability and availability of the server.

The ability to distinguish between 500 and 555 status codes provides similar value to User Defined Resource authors and end users of the User Defined Resource.

3. IANA Considerations

The HTTP Status Codes Registry should be updated with the following entry:

4. Security Considerations

When the server includes information that identifies the User Defined Resource that caused the error, or additional information that helps the author diagnose the root cause, care must be taken not to disclose information that may be useful to an attacker.

Care needs to be taken to ensure that the log messages do not reveal sensitive information about the users of the User Defined Resource, see [RFC7230] section 9.8 for relevant guidance on this topic.

5. Example

This section is non-normative.

Below is an example response that leverages the Problem Details for HTTP APIs syntax [RFC7807] to communicate information about the error condition:

HTTP/1.1 555 User Defined Resource Error
Content-Type: application/problem+json
Content-Language: en

{
 "type":     "https://example.com/errs/user-defined-resource-error",
 "title":    "User Defined Resource Error",
 "detail":   "An unexpected error condition occurred when
              evaluating a user defined resource",
 "trace_id": "a75382c4-d61d-4c16-8dde-a01afc7b51a2",
 "instance": "/logs/?trace_id=a75382c4-d61d-4c16-8dde-a01afc7b51a2"
}

6. Normative References

[RFC2119]
Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, , <https://www.rfc-editor.org/info/rfc2119>.
[RFC3986]
Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform Resource Identifier (URI): Generic Syntax", STD 66, RFC 3986, DOI 10.17487/RFC3986, , <https://www.rfc-editor.org/info/rfc3986>.
[RFC7231]
Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer Protocol (HTTP/1.1): Semantics and Content", RFC 7231, DOI 10.17487/RFC7231, , <https://www.rfc-editor.org/info/rfc7231>.
[RFC7230]
Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer Protocol (HTTP/1.1): Message Syntax and Routing", RFC 7230, DOI 10.17487/RFC7230, , <https://www.rfc-editor.org/info/rfc7230>.
[RFC7807]
Nottingham, M. and E. Wilde, "Problem Details for HTTP APIs", RFC 7807, DOI 10.17487/RFC7807, , <https://www.rfc-editor.org/info/rfc7807>.

Author's Address

Colm Divilly
Oracle Corporation