Add observer and geo metadata

It is often useful to view and query various attributes of the instance Heartbeat is running on. This data is attached to events via the add_observer_metadata processor. This processor populates the ECS observer.* fields. One field of particular utility is the observer.geo.name field, which you can configure via this processor. Use this field to create distinctive geographic regions for your uptime checks. You might label your regions by datacenter name or geographic region, e.g. virginia-dc-1, or us-east-1a, or virginia-us.

Note that Heartbeat should not be used with the similarly named add_host_metadata processor. In ECS parlance the host is the thing that is monitored, not the thing doing the monitoring, which is the observer.