Tackles kubernetes/autoscaler#1208. EC2 Metadata helpfully supplies AWS
Region info, so rather than _requiring_ an environment variable, this
patch enables `aws_manager.go` to retrieve that information from EC2
itself.
Example YAMLs no longer reference the vestigial `AWS_REGION` environment
variable, but supplying it to `cluster-autoscaler` still relays it to
the AWS SDK like before.
* Validate taint key with regex
Before attempting to perform a split on the tag value, validate it
matches the format <tag>:NoSchedule
This should prevent invalid tag keys from causing the autoscaler to
panic and crash
* Further taint validation
Also add test cases for valid taint methods
Instead of doing auto-discovery, nodes per ASG and target size per ASG separately, fetch all
of those ASG details in a single request on each Refresh() with maximum 10 seconds granularity.
Node group discovery is now handled by cloudprovider.Refresh() in all cases.
Additionally, explicit node groups can now be used alongside autodiscovery.
Shatil Rafiullah
Sheldon Kwok
Lee Briggs
Johannes Würbach
Aleksandra Malinowska
Nic Cope
mmerrill3
Seth Pollack