Resource attributes for network addresses of a host

[mx-psi]

The Elastic Common Schema defines the semantic conventions host.ip and host.mac, that state, respectively, the known IP and MAC addresses of a given host.

This issue tracks incorporating them into the OpenTelemetry semantic conventions. There are two open questions or clarifications that I feel need to be resolved before adding these to OpenTelemetry:

1. Should IPv4 and IPv6 be distinguished in separate semantic conventions?
2. Should this belong to the host namespace of is this a network semantic convention that should be under the system.network namespace?

These may be part of open-telemetry/opentelemetry-specification#3556 if approved.

[ChrsMark]

Hey @mx-psi!

Regarding the distinction of IPv4 and IPV6 I like the idea of being more specific.

About the second question: From infrastructure perspective I would consider host.ip and host.mac as attributes of a given host. So I would say that we could follow ECS in that part without an issue.

Another thing that we might consider here related to the second question is if it would make sense to report system metrics under the host.* namespace as well. So instead of system.cpu.utilization we use sth like host.cpu.utilization. This was covered by ECS at elastic/ecs#2129.
On this we will need to also take into account how we will report metrics from other entities like containers and VMs. We would need to make the topology distinction clear so as to not mix things.

[mx-psi]

Filed #203 for the IPv4 and IPv6 addresses case.

[Oberon00]

AFAIK, we intentionally left out these attributes because we want to delay defining them until after we sort out how to implement mutable/added-after-start resource attributes: open-telemetry/opentelemetry-specification#1298
IP addresses may change after startup (theoretically also the MAC, but that would be an edge case that can probably be ignored, except if someone knows better, e.g. re. IPv6 privacy features?)

[mx-psi]

Closing this since we now have host.ip and host.mac