* For Container Linux or Flatcar Linux alpha/beta/stable,
continue using the `cgroupfs` driver
* For Fedora Atomic, continue using the `systemd` driver
* For Flatcar Linux Edge, use the `systemd` driver
* Replace v0.11 bracket type hints with Terraform v0.12 list expressions
* Use expression syntax instead of interpolated strings, where suggested
* Update AWS tutorial and worker pools documentation
* Define Terraform and plugin version requirements in versions.tf
* Require aws ~> 2.7 to support Terraform v0.12
* Require ct ~> 0.3.2 to support Terraform v0.12
* This change affects users who use worker pools on AWS, GCP, or
Azure with a Container Linux derivative
* Rename worker pool modules' `count` variable to `worker_count`,
because `count` will be a reserved variable name in Terraform v0.12
* Add ability to load balance TCP applications (e.g. NodePort)
* Output the network load balancer ARN as `nlb_id`
* Accept a `worker_target_groups` (ARN) list to which worker
instances should be added
* AWS NLBs and target groups don't support UDP
* terraform-render-bootkube module deprecated kube_dns_service_ip
output in favor of cluster_dns_service_ip
* Rename k8s_dns_service_ip to cluster_dns_service_ip for
consistency too
* Basic monitoring (free) is sufficient for casual console browsing
* Detailed monitoring (paid) is not leveraged for CloudWatch anyway
* Favor Prometheus for cloud-agnostic metrics, aggregation, and alerting
* Simplify clusters to come with a single NLB
* Listen for apiserver traffic on port 6443 and forward
to controllers (with healthy apiserver)
* Listen for ingress traffic on ports 80/443 and forward
to workers (with healthy ingress controller)
* Reduce cost of default clusters by 1 NLB ($18.14/month)
* Keep using CNAME records to the `ingress_dns_name` NLB and
the nginx-ingress addon for Ingress (up to a few million RPS)
* Users with heavy traffic (many million RPS) can create their
own separate NLB(s) for Ingress and use the new output worker
target groups
* Fix issue where additional worker pools come with an
extraneous network load balancer
* Replace os_channel variable with os_image to align naming
across clouds. Users who set this option to stable, beta, or
alpha should now set os_image to coreos-stable, coreos-beta,
or coreos-alpha.
* Default os_image to coreos-stable. This continues to use
the most recent image from the stable channel as always.
* Allow Container Linux derivative Flatcar Linux by setting
os_image to `flatcar-stable`, `flatcar-beta`, `flatcar-alpha`
* Add `worker_price` to allow worker spot instances. Defaults
to empty string for the worker autoscaling group to use regular
on-demand instances.
* Add `spot_price` to internal `workers` module for spot worker
pools
* Note: Unlike GCP `preemptible` workers, spot instances require
you to pick a bid price.
* Change EBS volume type from `standard` ("prior generation)
to `gp2`. Prometheus alerts are tuned for SSDs
* Other platforms have fast enough disks by default
Dalton Hubble
Tamer Fahmy
Robert Fairburn