* 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
* 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)
* Fix issue where Azure defaults to Deallocate eviction policy,
which required manually restarting deallocated workers
* Require terraform-provider-azurerm v1.19+ to support setting
the eviction_policy
* 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)
* 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)
* Fix issue where worker nodes didn't delete themselves on
scale-down or deallocation (e.g. low priority instances).
Lowercase the hostname and delete the Kubernetes node
* Kubelet registers the lowercase hostname as the node name,
but Azure workers get hostname CLUSTER-worker-GENERATED where
the generated identifier may contain uppercase characters
