* Use flexible orchestration mode. Azure has started to recommend this
mode because it allows interacting with VMSS instances like regular VMs
via the CLI or via the Azure Portal
* Add options to allow workers nodes to use ephemeral local disks
* Add `controller_disk_type` and `controller_disk_size` variables
* Add `worker_disk_type`, `worker_disk_size`, and `worker_ephemeral_disk` variables
* Rename the region variable to location to align with Azure
platform conventions, where resources are created within an
Azure location, which are themselves part of broader geographical
regions
* Define a dual-stack virtual network with both IPv4 and IPv6 private
address space. Change `host_cidr` variable (string) to a `network_cidr`
variable (object) with "ipv4" and "ipv6" fields that list CIDR strings.
* Define dual-stack controller and worker subnets. Disable Azure
default outbound access (a deprecated fallback mechanism)
* Enable dual-stack load balancing to Kubernetes Ingress by adding
a public IPv6 frontend IP and LB rule to the load balancer.
* Enable worker outbound IPv6 connectivity through load balancer
SNAT by adding an IPv6 frontend IP and outbound rule
* Configure controller nodes with a public IPv6 address to provide
direct outbound IPv6 connectivity
* Add an IPv6 worker backend pool. Azure requires separate IPv4 and
IPv6 backend pools, though the health probe can be shared
* Extend network security group rules for IPv6 source/destinations
Checklist:
Access to controller and worker nodes via IPv6 addresses:
* SSH access to controller nodes via public IPv6 address
* SSH access to worker nodes via (private) IPv6 address (via
controller)
Outbound IPv6 connectivity from controller and worker nodes:
```
nc -6 -zv ipv6.google.com 80
Ncat: Version 7.94 ( https://nmap.org/ncat )
Ncat: Connected to [2607:f8b0:4001:c16::66]:80.
Ncat: 0 bytes sent, 0 bytes received in 0.02 seconds.
```
Serve Ingress traffic via IPv4 or IPv6 just requires setting
up A and AAAA records and running the ingress controller with
`hostNetwork: true` since, hostPort only forwards IPv4 traffic
* Allow passing a dummy RSA key to Azure to satisfy its obtuse
requirements (recommend deleting the corresponding private key)
* Then `ssh_authorized_key` can be used to provide Fedora CoreOS
or Flatcar Linux with a modern ed25519 public key to set in the
authorized_keys via Ignition
* Kinvolk now publishes Flatcar Linux images for ARM64
* For now, amd64 image must specify a plan while arm64 images
must NOT specify a plan due to how Kinvolk publishes.
Rel: https://github.com/flatcar/Flatcar/issues/872
* CoreOS Container Linux was deprecated in v1.18.3
* Continue transitioning docs and modules from supporting
both CoreOS and Flatcar "variants" of Container Linux to
now supporting Flatcar Linux and equivalents
Action Required: Update the Flatcar Linux modules `source`
to replace `s/container-linux/flatcar-linux`. See docs for
examples
