* Require the controller module to be completed before starting
to remote exec bootkube start, otherwise its possible the controller
nodes were created, but not the network load balancer
* Prometheus proxies through the apiserver to scrape kubelets
* In multi-controller setups, an apiserver must be able to scrape
kubelets (10250) on other controllers
* ELB distributing load across controllers is no longer the mechanism
used to SSH to instances to distribute secrets
* Focus the ELB on load balancing across apiserver and edit the HTTP
health check to an SSL:443 check
* Change controllers ASG to heterogeneous EC2 instances
* Create DNS records for each controller's private IP for etcd
* Change etcd to run on-host, across controllers (etcd-member.service)
* Reduce time to bootstrap a cluster
* Deprecate self-hosted-etcd on the AWS platform
* Change controllers from a managed group to individual instances
* Create discrete DNS records to each controller's private IP for etcd
* Change etcd to run on-host, across controllers (etcd-member.service)
* Reduce time to bootstrap a cluster
* Deprecate self-hosted-etcd on the Google Cloud platform
* Remove performance note that the GCE vs AWS network performance
is not an equal comparison. On both platforms, workers now span the
(availability) zones of a region.
* Testing host-to-host and pod-to-pod network bandwidth between nodes
(now located in different zones) showed no reduction in bandwidth
* Controller preemption is not safe or covered in documentation. Delete
the option, the variable is a holdover from old experiments
* Note, worker_preemeptible is still a great feature that's supported
* Change Google Cloud module to require the `region` variable
* Workers are created in random zones within the given region
* Tolerate Google Cloud zone failures or capacity issues
* If workers are preempted (if enabled), replacement instances can
be drawn from any zone in the region, which should avoid scheduling
issues that were possible before if a single zone aggressively
preempts instances (presumably due to Google Cloud capacity)
* Kubernetes v1.8.2 fixes a memory leak in the v1.8.1 apiserver
* Switch to using the `gcr.io/google_containers/hyperkube` for the
on-host kubelet and shutdown drains
* Update terraform-render-bootkube manifests generation
* Update flannel from v0.8.0 to v0.9.0
* Add `hairpinMode` to flannel CNI config
* Add `--no-negcache` to kube-dns dnsmasq
* Without this change, if a cluster doesn't set the controller
or worker networkd lists, an err "element() may not be used
with an empty list" occurs.
* controller_networkds and worker_networks are intended to be
optional and temporary, not required at all
* Accept ordered lists of controller and worker networkd configs
* Do not rely on these variables. They will be replaced with a
cleaner mechanism at a future date
