From 8f039d6df676f42713ba4dddab71c5bf7a248bcd Mon Sep 17 00:00:00 2001 From: David Ashpole Date: Wed, 11 Mar 2026 13:27:51 +0000 Subject: [PATCH] OM 2.0: recommend exemplar keys for trace context Signed-off-by: David Ashpole --- docs/specs/om/open_metrics_spec_2_0.md | 2 ++ 1 file changed, 2 insertions(+) diff --git a/docs/specs/om/open_metrics_spec_2_0.md b/docs/specs/om/open_metrics_spec_2_0.md index ec10d36fd..13a68e111 100644 --- a/docs/specs/om/open_metrics_spec_2_0.md +++ b/docs/specs/om/open_metrics_spec_2_0.md @@ -132,6 +132,8 @@ Exemplars MUST consist of a LabelSet and a value, and MUST have a timestamp. The The Exemplar's timestamp SHOULD be close to the point in time when the referenced data was created, but doesn't have to be exact. For example if getting an exact timestamp is costly, it is acceptable to use some external source or synthetic clock. +When an exemplar references a [Trace Context](https://www.w3.org/TR/trace-context-2/), it SHOULD use the `trace_id` key for the [trace-id](https://www.w3.org/TR/trace-context-2/#traceparent-header) field, and the `span_id` key for the [`parent-id`](https://www.w3.org/TR/trace-context-2/#traceparent-header) field. + While there's no [hard limit](#size-limits) specified, Exemplar's LabelSet SHOULD NOT be used to transport large data like tracing span details or other event logging. Ingestors MAY truncate the Exemplar's LabelSet or discard Exemplars.