* Set small CPU requests on static pods kube-apiserver,
kube-controller-manager, and kube-scheduler to align with
upstream tooling and for edge cases
* Effectively, a practical case for these requests hasn't been
observed. However, a small static pod CPU request may offer
a slight benefit if a controller became overloaded and the
below mechanisms were insufficient
Existing safeguards:
* Control plane nodes are tainted to isolate them from
ordinary workloads. Even dense workloads can only compress
CPU resources on worker nodes.
* Control plane static pods use the highest priority class, so
contention favors control plane pods (over say node-exporter)
and CPU is compressible too.
See: https://github.com/poseidon/terraform-render-bootstrap/pull/161
* Update terraform-render-bootstrap module to adopt the
Terrform v0.12 templatefile function feature to replace
the use of terraform-provider-template's `template_dir`
* Require Terraform v0.12.6+ which adds `for_each`
Background:
* `template_dir` was added to `terraform-provider-template`
to add support for template directory rendering in CoreOS
Tectonic Kubernetes distribution (~2017)
* Terraform v0.12 introduced a native `templatefile` function
and v0.12.6 introduced native `for_each` support (July 2019)
that makes it possible to replace `template_dir` usage
* Change `networking` default from flannel to calico on
Azure and DigitalOcean
* AWS, bare-metal, and Google Cloud continue to default
to Calico (as they have since v1.7.5)
* Typhoon now defaults to using Calico and supporting
NetworkPolicy on all platforms
* Review variables available in DigitalOcean kubernetes
module and sync with documentation
* Promote Calico for DigitalOcean and Azure beyond experimental
(its the primary mode I've used since it was introduced)
* Fix issue (present since bootkube->bootstrap switch) where
controller asset copy could fail if /etc/kubernetes/manifests
wasn't created in time on platforms using path activation for
the Kubelet (observed on DigitalOcean, also possible on
bare-metal)
* Drop `node-role.kubernetes.io/master` and
`node-role.kubernetes.io/node` node labels
* Kubelet (v1.16) now rejects the node labels used
in the kubectl get nodes ROLES output
* https://github.com/kubernetes/kubernetes/issues/75457
* Rename render module from bootkube to bootstrap. Avoid
confusion with the kubernetes-incubator/bootkube tool since
it is no longer used
* Use the poseidon/terraform-render-bootstrap Terraform module
(formerly poseidon/terraform-render-bootkube)
* https://github.com/poseidon/terraform-render-bootkube/pull/149
* Run a kube-apiserver, kube-scheduler, and kube-controller-manager
static pod on each controller node. Previously, kube-apiserver was
self-hosted as a DaemonSet across controllers and kube-scheduler
and kube-controller-manager were a Deployment (with 2 or
controller_count many replicas).
* Remove bootkube bootstrap and pivot to self-hosted
* Remove pod-checkpointer manifests (no longer needed)
* Allow updating terraform-provider-ct to any release
beyond v0.3.2, but below v1.0. This relaxes the prior
constraint that allowed only v0.3.y provider versions
* Run kube-apiserver as a non-root user (nobody). User
no longer needs to bind low number ports.
* On most platforms, the kube-apiserver load balancer listens
on 6443 and fronts controllers with kube-apiserver pods using
port 6443. Google Cloud TCP proxy load balancers cannot listen
on 6443. However, GCP's load balancer can be made to listen on
443, while kube-apiserver uses 6443 across all platforms.
* Replace v0.11 bracket type hints with Terraform v0.12 list expressions
* Use expression syntax instead of interpolated strings, where suggested
* Update DigitalOcean tutorial documentation
* Define Terraform and plugin version requirements in versions.tf
* Require digitalocean ~> v1.3 to support Terraform v0.12
* Require ct ~> v0.3.2 to support Terraform v0.12
* Fix to remove a trailing slash that was erroneously introduced
in the scripting that updated from v1.14.1 to v1.14.2
* Workaround before this fix was to re-run `terraform init`
* Introduce "calico" as a `networking` option on Azure and DigitalOcean
using Calico's new VXLAN support (similar to flannel). Flannel remains
the default on these platforms for now.
* Historically, DigitalOcean and Azure only allowed Flannel as the
CNI provider, since those platforms don't support IPIP traffic that
was previously required for Calico.
* Looking forward, its desireable for Calico to become the default
across Typhoon clusters, since it provides NetworkPolicy and a
consistent experience
* No changes to AWS, GCP, or bare-metal where Calico remains the
default CNI provider. On these platforms, IPIP mode will always
be used, since its available and more performant than vxlan
* DigitalOcean clusters must secure copy a kubeconfig to
worker nodes, but Terraform could decide to try copying
before firewall rules have been added to allow SSH access.
* Add an explicit dependency on adding firewall rules first
* Change flannel port from the kernel default 8472 to the
IANA assigned VXLAN port 4789
* Update firewall rules or security groups for VXLAN
* Why now? Calico now offers its own VXLAN backend so
standardizing on the IANA port will simplify config
* https://github.com/coreos/flannel/blob/master/Documentation/backends.md#vxlan
* Add an `enable_aggregation` variable to enable the kube-apiserver
aggregation layer for adding extension apiservers to clusters
* Aggregation is **disabled** by default. Typhoon recommends you not
enable aggregation. Consider whether less invasive ways to achieve your
goals are possible and whether those goals are well-founded
* Enabling aggregation and extension apiservers increases the attack
surface of a cluster and makes extensions a part of the control plane.
Admins must scrutinize and trust any extension apiserver used.
* Passing a v1.14 CNCF conformance test requires aggregation be enabled.
Having an option for aggregation keeps compliance, but retains the
stricter security posture on default clusters
* Define firewall rules on DigitialOcean to match rules used on AWS,
GCP, and Azure
* Output `controller_tag` and `worker_tag` to simplify custom firewall
rule creation
* 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/
* Restore the original special-casing of DigitalOcean Kubelets
* Fix node metadata InternalIP being set to the IP of the default
gateway on DigitalOcean nodes (regressed in v1.12.3)
* Reverts the "pretty" node names on DigitalOcean (worker-2 vs IP)
* Closes#424 (full details)
* 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)
* 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
* 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
* 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)
* Improve the workers "round-robin" DNS FQDN that is created
with each cluster by adding AAAA records
* CNAME's resolving to the DigitalOcean `workers_dns` output
can be followed to find a droplet's IPv4 or IPv6 address
* The CNI portmap plugin doesn't support IPv6. Hosting IPv6
apps is possible, but requires editing the nginx-ingress
addon with `hostNetwork: true`
* 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)
* Require a terraform-provider-digitalocean plugin version of
1.0 or higher within the same major version (e.g. allow 1.1 but
not 2.0)
* Change requirement from ~> 0.1.2 (which allowed up to but not
including 1.0 release)
* Add new bird and felix readiness checks
* Read MTU from ConfigMap veth_mtu
* Add RBAC read for serviceaccounts
* Remove invalid description from CRDs
* Release v1.11.1 erroneously left Fedora Atomic clusters using
the v1.11.0 Kubelet. The rest of the control plane ran v1.11.1
as expected
* Update Kubelet from v1.11.0 to v1.11.1 so Fedora Atomic matches
Container Linux
* Container Linux modules were not affected
* 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
* 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
* (containerized) kube-proxy warns that it is unable to
load the ip_vs kernel module despite having the correct
mounts. Atomic uses an xz compressed module and modprobe
in the container was not compiled with compression support
* Workaround issue for now by always loading ip_vs on-host
* https://github.com/kubernetes/kubernetes/issues/60
