logging: instance_name label is not valid for GCE Instance Resource

[hopkiw]

google-cloud-go/logging/resource.go

Line 205 in 0232e6f

"instance_name": name,

This code automatically detects and adds an instance_name label to the common resource object. However, the instance_name label never appears on any logs on the service side. I believe this is because the GCE instance resource only accepts a pre-validated set of labels which are the project, zone and instance ID. The code here should not add or send the instance_name label, and probably the service should reject resources with invalid labels to aid in discovery.

[hopkiw]

Alternately, the service could be updated to consider instance_name a valid label for a GCE Instance resource. This would have the added benefit of affecting existing software retroactively which is currently trying to send this label.

[minherz]

@hopkiw thank you for pointing to this problem. we will remove the code to align the behavior with the documented set of labels reported by logging agents for the GCE instances.

[minherz]

While it is possible to keep the instance_name label, its use is undesirable in events of GCE instance renaming.