[exporter/datadog] Improvements in hostname resolution

[mx-psi]

Overview

The Datadog exporter relies on the resourcedetection processor and k8attributes processor for supporting hostname resolution on certain environments; this has limitations when monitoring remote hosts with a single Datadog exporter. To improve the behavior on these setups, the exporter will resolve the hostname natively in all supported setups. This will cause changes in the identified hostname for certain setups. Initially these changes will be available behind a feature flag.

Feature gate summary

Feature gate	Introduced as alpha in	Switched to beta in	Removed in
exporter.datadog.hostname.preview	v0.54.0	v0.56.0	v0.76.1

Refer to the feature lifecycle documentation to understand the different stages a feature gate can be in and to the usage instructions to understand how to control the feature gate.

Changes introduced by the feature gate

The feature gate applies the following changes to the hostname resolution rules on the Datadog exporter:

• The default value of host_metadata::hostname_source is set to config_or_system
• The hostname is added on telemetry data that lacks it without using processors on all supported environments (Azure, AWS EC2, AWS ECS Fargate, Google Cloud and Kubernetes) .
• The hostname resolved from attributes is consistent to the one reported by Datadog cloud integrations.