Tracing: maintain list of peer services => domain name

[cedricziel]

Why

In OTel, client spans can be marked with the peer.service attribute.

In the standard service graph calculation, this attribute causes a new node in the service graph to be mapped.

Example:

span:
  http.url: https://salesforce.com/foo
  peer.service: acmeforce.com

This will introduce an acmeforce.com node into the graph and calculate RED metrics towards that node. This is useful, because normally, no nodes are created and using the peer.service attribute will trigger that (similar to a handful of other attributes like db.name).

What

The proposal is to add a configuration for domain names and when encountered on spans with kind=client, http.url=$domain, add a new peer.service=$nodeName.

Illustrative example config:

peers:
  # explicit scoping could eventually address more use-cases
  domains:
    nodeName: ^force.com$

[grcevski]

Good proposal! Just to clarify, the feature request is not simply to derive peer.service based on the domain in http.url, it should also allow for substitutions based on defined rules. If it just adding the peer.service attribute it's very easy for us to do.