* Fedora CoreOS now ships systemd-udev's `default.link` while
Flannel relies on being able to pick its own MAC address for
the `flannel.1` link for tunneled traffic to reach cni0 on
the destination side, without being dropped
* This change first appeared in FCOS testing-devel 32.20200624.20.1
and is the behavior going forward in FCOS since it was added
to align FCOS network naming / configs with the rest of Fedora
and address issues related to the default being missing
* Flatcar Linux (and Container Linux) has a specific flannel.link
configuration builtin, so it was not affected
* https://github.com/coreos/fedora-coreos-tracker/issues/574#issuecomment-665487296
Note: Typhoon's recommended and default CNI provider is Calico,
unless `networking` is set to flannel directly.
* Set Kubelet cgroup driver to systemd when Flatcar Linux edge
is chosen
Note: Typhoon module status assumes use of the stable variant of
an OS channel/stream. Its possible to use earlier variants and
those are sometimes tested or developed against, but stable is
the recommendation
* In v1.18.3, the `os_stream` variable was added to select
a Fedora CoreOS image stream (stable, testing, next) on
AWS and Google Cloud (which publish official streams)
* Remove `os_image` variable deprecated in v1.18.3. Manually
uploaded images are no longer needed
* DigitalOcean introduced Virtual Private Cloud (VPC) support
to match other clouds and enhance the prior "private networking"
feature. Before, droplet's belonging to different clusters (but
residing in the same region) could reach one another (although
Typhoon firewall rules prohibit this). Now, droplets in a VPC
reside in their own network
* https://www.digitalocean.com/docs/networking/vpc/
* Create droplet instances in a VPC per cluster. This matches the
design of Typhoon AWS, Azure, and GCP.
* Require `terraform-provider-digitalocean` v1.16.0+ (action required)
* Output `vpc_id` for use with an attached DigitalOcean
loadbalancer
* Accept experimental CNI `networking` mode "cilium"
* Run Cilium v1.8.0-rc4 with overlay vxlan tunnels and a
minimal set of features. We're interested in:
* IPAM: Divide pod_cidr into /24 subnets per node
* CNI networking pod-to-pod, pod-to-external
* BPF masquerade
* NetworkPolicy as defined by Kubernetes (no L7 Policy)
* Continue using kube-proxy with Cilium probe mode
* Firewall changes:
* Require UDP 8472 for vxlan (Linux kernel default) between nodes
* Optional ICMP echo(8) between nodes for host reachability
(health)
* Optional TCP 4240 between nodes for endpoint reachability (health)
Known Issues:
* Containers with `hostPort` don't listen on all host addresses,
these workloads must use `hostNetwork` for now
https://github.com/cilium/cilium/issues/12116
* Erroneous warning on Fedora CoreOS
https://github.com/cilium/cilium/issues/10256
Note: This is experimental. It is not listed in docs and may be
changed or removed without a deprecation notice
Related:
* https://github.com/poseidon/terraform-render-bootstrap/pull/192
* https://github.com/cilium/cilium/issues/12217
* Change the Calico VXLAN interface for MTU from 1450 to 1410
* VXLAN on Azure should support MTU 1450. However, there is
history where performance measures have shown that 1410 is
needed to have expected performance. Flatcar Linux has the
same MTU 1410 override and note
* FCOS 31.20200323.3.2 was known to perform fine with 1450, but
now in 31.20200517.3.0 the right value seems to be 1410
* Fedora CoreOS `kubelet.service` can start before the hostname
is set. Kubelet reads the hostname to determine the node name to
register. If the hostname was read as localhost, Kubelet will
continue trying to register as localhost (problem)
* This race manifests as a node that appears NotReady, the Kubelet
is trying to register as localhost, while the host itself (by then)
has an AWS provided hostname. Restarting kubelet.service is a
manual fix so Kubelet re-reads the hostname
* This race could only be shown on AWS, not on Google Cloud or
Azure despite attempts. Bare-metal and DigitalOcean differ and
use hostname-override (e.g. afterburn) so they're not affected
* Wait for nodes to have a non-localhost hostname in the oneshot
that awaits /etc/resolve.conf. Typhoon has no valid cases for a
node hostname being localhost (not even single-node clusters)
Related Openshift: https://github.com/openshift/machine-config-operator/pull/1813
Close https://github.com/poseidon/typhoon/issues/765
* Remove node label `node.kubernetes.io/master` from controller nodes
* Use `node.kubernetes.io/controller` (present since v1.9.5,
[#160](https://github.com/poseidon/typhoon/pull/160)) to node select controllers
* Rename controller NoSchedule taint from `node-role.kubernetes.io/master` to
`node-role.kubernetes.io/controller`
* Tolerate the new taint name for workloads that may run on controller nodes
and stop tolerating `node-role.kubernetes.io/master` taint
* Kubelet `--lock-file` and `--exit-on-lock-contention` date
back to usage of bootkube and at one point running Kubelet
in a "self-hosted" style whereby an on-host Kubelet (rkt)
started pods, but then a Kubelet DaemonSet was scheduled
and able to take over (hence self-hosted). `lock-file` and
`exit-on-lock-contention` flags supported this pivot. The
pattern has been out of favor (in bootkube too) for years
because of dueling Kubelet complexity
* Typhoon runs Kubelet as a container via an on-host systemd
unit using podman (Fedora CoreOS) or rkt (Flatcar Linux). In
fact, Typhoon no longer uses bootkube or control plane pivot
(let alone Kubelet pivot) and uses static pods since v1.16.0
* https://github.com/poseidon/typhoon/pull/536
* Generated Kubelet TLS certificate and key are not longer
used or distributed to machines since Kubelet TLS bootstrap
is used instead. Remove the certificate and key from state
* Enable terraform-provider-ct `strict` mode for parsing
Container Linux Configs and snippets
* Fix Container Linux Config systemd unit syntax `enable`
(old) to `enabled`
* Align with Fedora CoreOS which uses strict mode already
