* loop sends an initial query to detect infinite forwarding
loops in configured upstream DNS servers and fast exit with
an error (its a fatal misconfiguration on the network that
will otherwise cause resolvers to consume memory/CPU until
crashing, masking the problem)
* https://github.com/coredns/coredns/tree/master/plugin/loop
* loadbalance randomizes the ordering of A, AAAA, and MX records
in responses to provide round-robin load balancing (as usual,
clients may still cache responses though)
* https://github.com/coredns/coredns/tree/master/plugin/loadbalance
* Prefer InternalIP and ExternalIP over the node's hostname,
to match upstream behavior and kubeadm
* Previously, hostname-override was used to set node names
to internal IP's to work around some cloud providers not
resolving hostnames for instances (e.g. DO droplets)
* Updating the `terraform-provider-ct` plugin is known to produce
a `user_data` diff in all pre-existing clusters. Applying the
diff to pre-existing cluster destroys controller nodes
* Ignore changes to controller `user_data`. Once all managed
clusters use a release containing this change, it is possible
to update the `terraform-provider-ct` plugin (worker `user_data`
will still be modified)
* Changing the module `ref` for an existing cluster and
re-applying is still NOT supported (although this PR
would protect controllers from being destroyed)
* Allowing serving IPv6 applications via Kubernetes Ingress
on Typhoon Google Cloud clusters
* Add `ingress_static_ipv6` output variable for use in AAAA
DNS records
* Run at least two replicas of CoreDNS to better support
rolling updates (previously, kube-dns had a pod nanny)
* On multi-master clusters, set the CoreDNS replica count
to match the number of masters (e.g. a 3-master cluster
previously used replicas:1, now replicas:3)
* Add AntiAffinity preferred rule to favor distributing
CoreDNS pods across controller nodes nodes
* Continue to ensure scheduler and controller-manager run
at least two replicas to support performing kubectl edits
on single-master clusters (no change)
* For multi-master clusters, set scheduler / controller-manager
replica count to the number of masters (e.g. a 3-master cluster
previously used replicas:2, now replicas:3)
* Add new bird and felix readiness checks
* Read MTU from ConfigMap veth_mtu
* Add RBAC read for serviceaccounts
* Remove invalid description from CRDs
* Broaden internal-etcd firewall rule to allow etcd client
traffic (2379) from other controller nodes
* Previously, kube-apiservers were only able to connect to their
node's local etcd peer. While master node outages were tolerated,
reaching a healthy peer took longer than neccessary in some cases
* Reduce time needed to bootstrap a cluster
* Switch Ingress from regional network load balancers to global
HTTP/TCP Proxy load balancing
* Reduce cost by ~$19/month per cluster. Google bills the first 5
global and regional forwarding rules separately. Typhoon clusters now
use 3 global and 0 regional forwarding rules.
* Worker pools no longer include an extraneous load balancer. Remove
worker module's `ingress_static_ip` output.
* Add `ingress_static_ipv4` output variable
* Add `worker_instance_group` output to allow custom global load
balancing
* Deprecate `controllers_ipv4_public` module output
* Deprecate `ingress_static_ip` module output. Use `ingress_static_ipv4`
* Adjust firewall rules, security groups, cloud load balancers,
and generated kubeconfig's
* Facilitates some future simplifications and cost reductions
* Bare-Metal users who exposed kube-apiserver on a WAN via their
router or load balancer will need to adjust its configuration.
This is uncommon, most apiserver are on LAN and/or behind VPN
so no routing infrastructure is configured with the port number
* Use Kubelet bearer token authn/authz to scrape metrics
* Drop RBAC permission from nodes/proxy to nodes/metrics
* Stop proxying kubelet scrapes through the apiserver, since
this required higher privilege (nodes/proxy) and can add
load to the apiserver on large clusters
* Raise minimum Terraform version to v0.11.0
* Terraform v0.11.x has been supported since Typhoon v1.9.2
and Terraform v0.10.x was last released in Nov 2017. I'd like
to stop worrying about v0.10.x and remove migration docs as
a later followup
* Migration docs docs/topics/maintenance.md#terraform-v011x
