Add ELB proxy protocol support via the annotation
"service.beta.kubernetes.io/aws-load-balancer-proxy-protocol". This
allows servers like Nginx and Haproxy to retrieve the real IP address of
a remote client.
This is a better abstraction than passing in specific pieces of the
Service that each of the cloudproviders may or may not need. For
instance, many of the providers don't need a region, yet this is passed
in. Similarly many of the providers want a string IP for the load
balancer, but it passes in a converted net ip. Affinity is unused by
AWS. A provider change may also require adding a new parameter which has
an effect on all other cloud provider implementations.
Further, this will simplify adding provider specific load balancer
options, such as with labels or some other metadata. For example, we
could add labels for configuring the details of an AWS elastic load
balancer, such as idle timeout on connections, whether it is
internal or external, cross-zone load balancing, and so on.
Authors: @chbatey, @jsravn
Fix the AWS subnet lookup that checks if a subnet is public, which was
missing a few cases:
- Subnets without explicit routing tables, which use the main VPC
routing table.
- Routing tables not tagged with KubernetesCluster. The filter for this
is now removed.
AWS doesn't support type=LoadBalancer with UDP services. For now, we
simply skip over the test with type=LoadBalancer on AWS for the UDP
service.
Fix#20911
According to AWS, the ELB healthy threshold is "Number of consecutive health check successes before declaring an EC2 instance healthy." It has an unusual interaction with Kubernetes, since all nodes will enter either an unhealthy state or a healthy state together depending on the service's healthiness as a whole.
We have observed that if our service goes down for the unhealthy threshold (which is 2 checks at 30 second intervals = 60 seconds), then the ELB will stop serving traffic to all nodes in the cluster, and will wait for the healthy threshold (currently 10 * 30 = 300 seconds) AFTER the service is restored to add back the cluster nodes, meaning it remains unreachable for an extra 300 seconds.
With the new settings, the ELB will continue to timeout dead nodes after 60 seconds, but will restore healthy nodes after 20 seconds. The minimum value for healthyThreshold is 2, and the minimum value for interval is 5 seconds. I went for 10 seconds instead of the minimum sort of arbitrarily because I was not sure how much this value may affect the scalability of clusters in EC2, as it does put some extra load on the kube-proxy.
The ELB client lookup isn't necessary because the service
does not operate across regions. Instead the client should
be built like the others by querying for the region from
the master node's metadata service.
A lot of packages use StringSet, but they don't use anything else from
the util package. Moving StringSet into another package will shrink
their dependency trees significantly.
