* 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
* 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
* Switch from Azure Hypervisor generation 1 to generation 2
* Change default Azure `worker_type` from Standard_DS1_v2 to Standard_D2as_v5
* Get 2 VCPU, 7 GiB, 12500Mbps (vs 1 VCPU, 3.5GiB, 750 Mbps)
* Small increase in pay-as-you-go price ($53.29 -> $62.78)
* Small increase in spot price ($5.64/mo -> $7.37/mo)
* Change from Intel to AMD EPYC (`D2as_v5` cheaper than `D2s_v5`)
Notes: Azure makes you accept terms for each plan:
```
az vm image terms accept --publish kinvolk --offer flatcar-container-linux-free --plan stable-gen2
```
Rel:
* https://learn.microsoft.com/en-us/azure/virtual-machines/dasv5-dadsv5-series#dasv5-series
* https://learn.microsoft.com/en-us/azure/virtual-machines/dv2-dsv2-series#dsv2-series
* Typhoon now consistently uses Butane Configs for snippets
(variant `fcos` or `flatcar`). Previously snippets were either
Butane Configs (on FCOS) or Container Linux Configs (on Flatcar)
* Update docs on uploading Flatcar Linux DigitalOcean images
* Update docs on uploading Fedora CoreOS Azure images
* Use the official Kinvolk Flatcar Linux image on Google Cloud
* Change `os_image` from a custom image name to `flatcar-stable`
(default), `flatcar-beta`, or `flatcar-alpha` (**action required**)
* Change `os_image` from a required to an optional variable
* Promote Typhoon on Flatcar Linux / Google Cloud to stable
* Remove docs about needing to upload a Flatcar Linux image
manually on Google Cloud and drop support for custom images
* Add `arch` variable to Flatcar Linux AWS `kubernetes` and
`workers` modules. Accept `amd64` (default) or `arm64` to support
native arm64/aarch64 clusters or mixed/hybrid clusters with arm64
workers
* Requires `flannel` or `cilium` CNI
Similar to https://github.com/poseidon/typhoon/pull/875
