Retrieve all agent configurations. You must have read privileges for the APM and User Experience feature in Kibana. If agent configuration is not available on the current deployment, the API returns a 404.
etag is sent by the APM agent to indicate the etag of the last successfully applied configuration. If the etag matches an existing configuration its applied_by_agent property will be set to true. Every time a configuration is edited applied_by_agent is reset to false.