Add Flatcar Container Linux templates and e2e tests

This commit adds end-user templates and e2e tests for clusters using
Flatcar Container Linux.

Based-on-work-by: Jeremi Piotrowski <[email protected]>
Signed-off-by: Mateusz Gozdek <[email protected]>

Author: jepio

Makefile

@@ -706,7 +706,7 @@ kind-create: $(KUBECTL) ## Create capz kind cluster if needed.
 
 .PHONY: tilt-up
 tilt-up: install-tools kind-create ## Start tilt and build kind cluster if needed.
-	EXP_CLUSTER_RESOURCE_SET=true EXP_MACHINE_POOL=true tilt up
+	EXP_CLUSTER_RESOURCE_SET=true EXP_MACHINE_POOL=true EXP_KUBEADM_BOOTSTRAP_FORMAT_IGNITION=true tilt up
 
 .PHONY: delete-cluster
 delete-cluster: delete-workload-cluster  ## Deletes the example kind cluster "capz".

Tiltfile

@@ -23,6 +23,7 @@ settings = {
     "cert_manager_version": "v1.10.0",
     "kubernetes_version": "v1.24.6",
     "aks_kubernetes_version": "v1.24.6",
+    "flatcar_version": "3374.2.1",
 }
 
 keys = ["AZURE_SUBSCRIPTION_ID", "AZURE_TENANT_ID", "AZURE_CLIENT_SECRET", "AZURE_CLIENT_ID"]
@@ -337,6 +338,7 @@ def deploy_worker_templates(template, substitutions):
         "AZURE_CONTROL_PLANE_MACHINE_TYPE": "Standard_B2s",
         "WORKER_MACHINE_COUNT": "2",
         "AZURE_NODE_MACHINE_TYPE": "Standard_B2s",
+        "FLATCAR_VERSION": settings.get("flatcar_version"),
     }
 
     if flavor == "aks":

docs/book/src/SUMMARY.md

@@ -30,6 +30,7 @@
     - [Virtual Networks](./topics/custom-vnet.md)
     - [VM Identity](./topics/vm-identity.md)
     - [Windows](./topics/windows.md)
+    - [Flatcar](./topics/flatcar.md)
 - [Development](./developers/development.md)
     - [Kubernetes Developers](./developers/kubernetes-developers.md)
     - [Releasing](./developers/releasing.md)

docs/book/src/topics/flatcar.md

@@ -0,0 +1,41 @@
+# Flatcar Clusters
+
+## Overview
+
+CAPZ enables you to create Kubernetes clusters using Flatcar Container Linux on Microsoft Azure.
+
+### Image creation
+
+The testing reference images are built using [image-builder](https://github.com/kubernetes-sigs/image-builder) by Flatcar maintainers and published to the Flatcar CAPI Community Gallery on Azure with community gallery name `flatcar4capi-742ef0cb-dcaa-4ecb-9cb0-bfd2e43dccc0`.
+
+<aside class="note warning">
+
+<h1> Security </h1>
+
+The reference images are not updated with security fixes. They are intended only to facilitate testing and to help users try out Cluster API for Azure.
+
+The reference images should not be used in a production environment. It is highly recommended to [maintain your own custom image](#building-a-custom-image) instead.
+
+</aside>
+
+Find the latest published images:
+
+```console
+$ az sig image-definition list-community --location westeurope --public-gallery-name flatcar4capi-742ef0cb-dcaa-4ecb-9cb0-bfd2e43dccc0 --only-show-errors
+HyperVGeneration    Location    Name                                OsState      OsType    UniqueId
+------------------  ----------  ----------------------------------  -----------  --------  ---------------------------------------------------------------------------------------------------------------
+V2                  westeurope  flatcar-stable-amd64-capi-v1.23.13  Generalized  Linux     /CommunityGalleries/flatcar4capi-742ef0cb-dcaa-4ecb-9cb0-bfd2e43dccc0/Images/flatcar-stable-amd64-capi-v1.23.13
+V2                  westeurope  flatcar-stable-amd64-capi-v1.25.4   Generalized  Linux     /CommunityGalleries/flatcar4capi-742ef0cb-dcaa-4ecb-9cb0-bfd2e43dccc0/Images/flatcar-stable-amd64-capi-v1.25.4
+V2                  westeurope  flatcar-stable-amd64-capi-v1.26.0   Generalized  Linux     /CommunityGalleries/flatcar4capi-742ef0cb-dcaa-4ecb-9cb0-bfd2e43dccc0/Images/flatcar-stable-amd64-capi-v1.26.0
+$
+$ az sig image-version list-community --location westeurope --public-gallery-name flatcar4capi-742ef0cb-dcaa-4ecb-9cb0-bfd2e43dccc0 --only-show-errors --gallery-image-definition flatcar-stable-amd64-capi-v1.26.0
+ExcludeFromLatest    Location    Name      PublishedDate                     UniqueId
+-------------------  ----------  --------  --------------------------------  --------------------------------------------------------------------------------------------------------------------------------
+False                westeurope  3227.2.3  2022-12-09T18:05:58.830464+00:00  /CommunityGalleries/flatcar4capi-742ef0cb-dcaa-4ecb-9cb0-bfd2e43dccc0/Images/flatcar-stable-amd64-capi-v1.26.0/Versions/3227.2.3
+```
+
+If you would like customize your images please refer to the documentation on building your own [custom images](custom-images.md).
+
+## Trying it out
+
+To create a cluster using Flatcar Container Linux, use `flatcar` cluster flavor.

templates/cluster-template-flatcar.yaml

@@ -0,0 +1,9 @@
+namespace: default
+resources:
+  - ../base
+  - machine-deployment.yaml
+  - ../../azure-cluster-identity
+
+patchesStrategicMerge:
+  - patches/kubeadm-controlplane.yaml
+  - ../../azure-cluster-identity/azurecluster-identity-ref.yaml