Logging trace context compatibility document (#3331)

CHANGELOG.md

@@ -22,6 +22,8 @@ release.
   ([#3332](https://github.com/open-telemetry/opentelemetry-specification/pull/3332))
 - Remove log readme document status.
   ([#3334](https://github.com/open-telemetry/opentelemetry-specification/pull/3334))
+- Break out compatibility document on recording trace context in non-OTLP Log Format
+  ([#3331](https://github.com/open-telemetry/opentelemetry-specification/pull/3331))
 
 ### Resource
 

specification/compatibility/logging_trace_context.md

@@ -0,0 +1,70 @@
+# Trace Context in non-OTLP Log Formats
+
+**Status**: [Experimental](../document-status.md)
+
+<details>
+<summary>Table of Contents</summary>
+
+<!-- toc -->
+
+- [Overview](#overview)
+  * [Syslog RFC5424](#syslog-rfc5424)
+  * [Plain Text Formats](#plain-text-formats)
+  * [JSON Formats](#json-formats)
+  * [Other Structured Formats](#other-structured-formats)
+
+<!-- tocstop -->
+
+</details>
+
+## Overview
+
+OTLP Logs Records have top level fields
+representing [trace context](../logs/data-model.md#trace-context-fields). This
+document defines how trace context should be recorded in non-OTLP Log Formats.
+To summarize, the following field names should be used in legacy formats:
+
+- "trace_id" for [TraceId](../logs/data-model.md#field-traceid), hex-encoded.
+- "span_id" for [SpanId](../logs/data-model.md#field-spanid), hex-encoded.
+- "trace_flags" for [trace flags](../logs/data-model.md#field-traceflags), formatted
+  according to W3C traceflags format.
+
+All 3 fields are optional (see the [data model](../logs/data-model.md) for details of
+which combination of fields is considered valid).
+
+### Syslog RFC5424
+
+Trace id, span id and traceflags SHOULD be recorded via SD-ID "opentelemetry".
+
+For example:
+
+```
+[opentelemetry trace_id="102981ABCD2901" span_id="abcdef1010" trace_flags="01"]
+```
+
+### Plain Text Formats
+
+The fields SHOULD be recorded according to the customary approach used for a
+particular format (e.g. field:value format for LTSV). For example:
+
+```
+host:192.168.0.1<TAB>trace_id:102981ABCD2901<TAB>span_id:abcdef1010<TAB>time:[01/Jan/2010:10:11:23 -0400]<TAB>req:GET /health HTTP/1.0<TAB>status:200
+```
+
+### JSON Formats
+
+The fields SHOULD be recorded as top-level fields in the JSON structure. For example:
+
+```json
+{
+  "timestamp":1581385157.14429,
+  "body":"Incoming request",
+  "trace_id":"102981ABCD2901",
+  "span_id":"abcdef1010"
+}
+```
+
+### Other Structured Formats
+
+The fields SHOULD be recorded as top-level structured attributes of the log
+record as it is customary for the particular format.

specification/logs/README.md

@@ -25,11 +25,6 @@ aliases: [/docs/reference/specification/logs/overview]
 - [OpenTelemetry Collector](#opentelemetry-collector)
 - [Auto-Instrumenting Existing Logging](#auto-instrumenting-existing-logging)
 - [Specifications](#specifications)
-- [Trace Context in Legacy Formats](#trace-context-in-legacy-formats)
-  * [Syslog RFC5424](#syslog-rfc5424)
-  * [Plain Text Formats](#plain-text-formats)
-  * [JSON Formats](#json-formats)
-  * [Other Structured Formats](#other-structured-formats)
 
 <!-- tocstop -->
 
@@ -329,7 +324,8 @@ The benefit of using an intermediary medium is that how logs are produced and
 where they are written by the application requires no or minimal changes. The
 downside is that it requires the often non-trivial log file reading and parsing
 functionality. Parsing may also be not reliable if the output format is not
-well-defined.
+well-defined. For details on recording and parsing trace context,
+see [Trace Context in Non-OTLP Log Formats](../compatibility/logging_trace_context.md).
 
 #### Direct to Collector
 
@@ -449,57 +445,4 @@ standard output.
 * [Logs Data Model](./data-model.md)
 * [Event API](./event-api.md)
 * [Semantic Conventions](./semantic_conventions/README.md)
-
-## Trace Context in Legacy Formats
-
-Earlier we briefly mentioned that it is possible to modify existing applications
-so that they include the Request Context information in the emitted logs.
-
-[OTEP0114](https://github.com/open-telemetry/oteps/pull/114) defines how the
-trace context should be recorded in logs. To summarize, the following field
-names should be used in legacy formats:
-
-- "trace_id" for [TraceId](data-model.md#field-traceid), hex-encoded.
-- "span_id" for [SpanId](data-model.md#field-spanid), hex-encoded.
-- "trace_flags" for [trace flags](data-model.md#field-traceflags), formatted
-  according to W3C traceflags format.
-
-All 3 fields are optional (see the [data model](data-model.md) for details of
-which combination of fields is considered valid).
-
-### Syslog RFC5424
-
-Trace id, span id and traceflags SHOULD be recorded via SD-ID "opentelemetry".
-
-For example:
-
-```
-[opentelemetry trace_id="102981ABCD2901" span_id="abcdef1010" trace_flags="01"]
-```
-
-### Plain Text Formats
-
-The fields should be recorded according to the customary approach used for a
-particular format (e.g. field:value format for LTSV). For example:
-
-```
-host:192.168.0.1<TAB>trace_id:102981ABCD2901<TAB>span_id:abcdef1010<TAB>time:[01/Jan/2010:10:11:23 -0400]<TAB>req:GET /health HTTP/1.0<TAB>status:200
-```
-
-### JSON Formats
-
-The fields should be recorded as top-level fields in the JSON structure. For example:
-
-```json
-{
-  "timestamp":1581385157.14429,
-  "body":"Incoming request",
-  "trace_id":"102981ABCD2901",
-  "span_id":"abcdef1010"
-}
-```
-
-### Other Structured Formats
-
-The fields should be recorded as top-level structured attributes of the log
-record as it is customary for the particular format.
+* [Trace Context in non-OTLP Log Formats](../compatibility/logging_trace_context.md)