Problem

Relates to:

• Original discussion
• Brainstorming doc Quoting Prometheus Names
• OTEL Attribute compatibility section

We are creating this issue as part of the OTEL Support milestone so it will be OTEL oriented but the problem is general to prometheus and has been around for a long time.

OTel allows UTF-8 in label names while Prometheus has a much more restrictive set. This is causing friction for users when using Prometheus. In particular, . (dot) is a very common character in OTel and we convert that to _ when converting to Prometheus. For example, service.version becomes service_version.

While this might look trivial, it causes friction because the traces and logs are likely stored in other databases which don’t have this restriction. Hence context switching between different datasources is not trivial.

Design doc

In a previous dev summit the prometheus team had consensus that at this stage a design doc is required to discuss about this topic.