* Background: A managed instance group of workers is used in backend
services for global load balancing (HTTP/HTTPS Ingress) and output
for custom global load balancing use cases
* Add worker instances to a target pool load balancing TCP/UDP
applications (NodePort or proxied). Output as `worker_target_pool`
* Health check for workers with a healthy Ingress controller. Forward
rules (regional) to target pools don't support different external and
internal ports so choosing nodes with Ingress allows proxying as a
workaround
* A target pool is a logical grouping only. It doesn't add costs to
clusters or worker pools
* Add calico-ipam CRDs and RBAC permissions
* Switch IPAM from host-local to calico-ipam
* `calico-ipam` subnets `ippools` (defaults to pod CIDR) into
`ipamblocks` (defaults to /26, but set to /24 in Typhoon)
* `host-local` subnets the pod CIDR based on the node PodCIDR
field (set via kube-controller-manager as /24's)
* Create a custom default IPv4 IPPool to ensure the block size
is kept at /24 to allow 110 pods per node (Kubernetes default)
* Retaining host-local was slightly preferred, but Calico v3.6
is migrating all usage to calico-ipam. The codepath that skipped
calico-ipam for KDD was removed
* https://docs.projectcalico.org/v3.6/release-notes/
* Resolve in-addr.arpa and ip6.arpa DNS PTR requests for Kubernetes
service IPs and pod IPs
* Previously, CoreDNS was configured to resolve in-addr.arpa PTR
records for service IPs (but not pod IPs)
* Support terraform-provider-google v1.19.0, v1.19.1, v1.20.0
and v2.0+ (and allow for future 2.x.y releases)
* Require terraform-provider-google v1.19.0 or newer. v1.19.0
introduced `network_interface` fields `network_ip` and `nat_ip`
to deprecate `address` and `assigned_nat_ip`. Those deprecated
fields are removed in terraform-provider-google v2.0
* https://github.com/terraform-providers/terraform-provider-google/releases/tag/v2.0.0
* Assign pod priorityClassNames to critical cluster and node
components (higher is higher priority) to inform node out-of-resource
eviction order and scheduler preemption and scheduling order
* Priority Admission Controller has been enabled since Typhoon
v1.11.1
* Intel Haswell or better is available in every zone around the world
* Neither Kubernetes nor Typhoon have a particular minimum processor
family. However, a few Google Cloud zones still default to Sandy/Ivy
bridge (scheduled to shift April 2019). Price is only based on machine
type so it is beneficial to opt for the next processor family
* Intel Haswell is a suitable minimum since it still allows plenty of
liberty in choosing any region or machine type
* Likely a slight increase to preemption probability in a few zones,
but any lower probability on Sandy/Ivy bridge is due to lower
desirability as they're phased out
* https://cloud.google.com/compute/docs/regions-zones/
* Fix a regression caused by lowering the Kubelet TLS client
certificate to system:nodes group (#100) since dropping
cluster-admin dropped the Kubelet's ability to delete nodes.
* On clouds where workers can scale down (manual terraform apply,
AWS spot termination, Azure low priority deletion), worker shutdown
runs the delete-node.service to remove a node to prevent NotReady
nodes from accumulating
* Allow Kubelets to delete cluster nodes via system:nodes group. Kubelets
acting with system:node and kubelet-delete ClusterRoles is still an
improvement over acting as cluster-admin
* System components that require certificates signed by the cluster
CA can submit a CSR to the apiserver, have an administrator inspect
and approve it, and be issued a certificate
* Configure kube-controller-manager to sign Approved CSR's using the
cluster CA private key
* Admins are responsible for approving or denying CSRs, otherwise,
no certificate is issued. Read the Kubernetes docs carefully and
verify the entity making the request and the authorization level
* https://kubernetes.io/docs/tasks/tls/managing-tls-in-a-cluster
* Use a single admin kubeconfig for initial bootkube bootstrap
and for use by a human admin. Previously, an admin kubeconfig
without a named context was used for bootstrap and direct usage
with KUBECONFIG=path, while one with a named context was used
for `kubectl config use-context` style usage. Confusing.
* Provide the admin kubeconfig via `assets/auth/kubeconfig`,
`assets/auth/CLUSTER-config`, or output `kubeconfig-admin`
* 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
* Kubelets can use a lower-privilege TLS client certificate with
Org system:nodes and a binding to the system:node ClusterRole
* Admin kubeconfig's continue to belong to Org system:masters to
provide cluster-admin (available in assets/auth/kubeconfig or as
a Terraform output kubeconfig-admin)
* Remove bare-metal output variable kubeconfig
* Add ServiceAccounts and ClusterRoleBindings for kube-apiserver
and kube-scheduler
* Remove the ClusterRoleBinding for the kube-system default ServiceAccount
* Rename the CA certificate CommonName for consistency with upstream
* On GCP, kubectl port-forward connections to pods are closed
after a timeout (unlike AWS NLB's or Azure load balancers)
* Increase the GCP apiserver backend service timeout from 1 minute
to 5 minutes to be more similar to AWS/Azure LB behavior
* Add kube-router for pod networking and NetworkPolicy
as an experiment
* Experiments are not documented or supported in any way,
and may be removed without notice. They have known issues
and aren't enabled without special options.
* Remove bullet about isolating workloads on workers, its
now common practice and new users will assume it
* List advanced features available in each module
* Fix erroneous Kubernetes version listing for Google Cloud
Fedora Atomic
* Calico Felix has been reporting anonymous usage data about the
version and cluster size, which violates Typhoon's privacy policy
where analytics should be opt-in only
* Add a variable enable_reporting (default: false) to allow opting
in to reporting usage data to Calico (or future components)
* 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
