* 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
* Introduce the ability to support Container Linux Config
"snippets" for controllers and workers on cloud platforms.
This allows end-users to customize hosts by providing Container
Linux configs that are additively merged into the base configs
defined by Typhoon. Config snippets are validated, merged, and
show any errors during `terraform plan`
* Example uses include adding systemd units, network configs,
mounts, files, raid arrays, or other disk provisioning features
provided by Container Linux Configs (using Ignition low-level)
* Requires terraform-provider-ct v0.2.1 plugin
* This reverts commit cce4537487.
* Provider passing to child modules is complex and the behavior
changed between Terraform v0.10 and v0.11. We're continuing to
allow both versions so this change should be reverted. For the
time being, those using our internal Terraform modules will have
to be aware of the minimum version for AWS and GCP providers,
there is no good way to do enforcement.
* Allow groups of workers to be defined and joined to
a cluster (i.e. worker pools)
* Move worker resources into a Terraform submodule
* Output variables needed for passing to worker pools
* Add usage docs for AWS worker pools (advanced)
