Allow using Flatcar Linux edge on Azure

* 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

CHANGES.md

@@ -18,12 +18,18 @@ Notable changes between versions.
 
 ### Fedora CoreOS
 
-#### Google
+#### Google Cloud
 
 * Promote Fedora CoreOS to stable
-* Remove `os_image` variable (deprecated in v1.18.3)
+* Remove `os_image` variable deprecated in v1.18.3 ([#777](https://github.com/poseidon/typhoon/pull/777))
   * Use `os_stream` to select a Fedora CoreOS image stream
 
+### Flatcar Linux
+
+#### Azure
+
+* Allow using Flatcar Linux Edge by setting `os_image` to "flatcar-edge" ([#778](https://github.com/poseidon/typhoon/pull/778))
+
 #### Addons
 
 * Update Prometheus from v2.19.0 to [v2.19.1](https://github.com/prometheus/prometheus/releases/tag/v2.19.1)

azure/container-linux/kubernetes/cl/controller.yaml

@@ -53,6 +53,7 @@ systemd:
         Wants=rpc-statd.service
         [Service]
         Environment=KUBELET_IMAGE=docker://quay.io/poseidon/kubelet:v1.18.5
+        Environment=KUBELET_CGROUP_DRIVER=${cgroup_driver}
         ExecStartPre=/bin/mkdir -p /etc/kubernetes/cni/net.d
         ExecStartPre=/bin/mkdir -p /etc/kubernetes/manifests
         ExecStartPre=/bin/mkdir -p /opt/cni/bin
@@ -96,6 +97,7 @@ systemd:
           --authentication-token-webhook \
           --authorization-mode=Webhook \
           --bootstrap-kubeconfig=/etc/kubernetes/kubeconfig \
+          --cgroup-driver=$${KUBELET_CGROUP_DRIVER} \
           --client-ca-file=/etc/kubernetes/ca.crt \
           --cluster_dns=${cluster_dns_service_ip} \
           --cluster_domain=${cluster_domain_suffix} \

azure/container-linux/kubernetes/controllers.tf

@@ -157,6 +157,7 @@ data "template_file" "controller-configs" {
     etcd_domain = "${var.cluster_name}-etcd${count.index}.${var.dns_zone}"
     # etcd0=https://cluster-etcd0.example.com,etcd1=https://cluster-etcd1.example.com,...
     etcd_initial_cluster   = join(",", data.template_file.etcds.*.rendered)
+    cgroup_driver          = local.flavor == "flatcar" && local.channel == "edge" ? "systemd" : "cgroupfs"
     kubeconfig             = indent(10, module.bootstrap.kubeconfig-kubelet)
     ssh_authorized_key     = var.ssh_authorized_key
     cluster_dns_service_ip = cidrhost(var.service_cidr, 10)

azure/container-linux/kubernetes/workers/cl/worker.yaml

@@ -26,6 +26,7 @@ systemd:
         Wants=rpc-statd.service
         [Service]
         Environment=KUBELET_IMAGE=docker://quay.io/poseidon/kubelet:v1.18.5
+        Environment=KUBELET_CGROUP_DRIVER=${cgroup_driver}
         ExecStartPre=/bin/mkdir -p /etc/kubernetes/cni/net.d
         ExecStartPre=/bin/mkdir -p /etc/kubernetes/manifests
         ExecStartPre=/bin/mkdir -p /opt/cni/bin
@@ -69,6 +70,7 @@ systemd:
           --authentication-token-webhook \
           --authorization-mode=Webhook \
           --bootstrap-kubeconfig=/etc/kubernetes/kubeconfig \
+          --cgroup-driver=$${KUBELET_CGROUP_DRIVER} \
           --client-ca-file=/etc/kubernetes/ca.crt \
           --cluster_dns=${cluster_dns_service_ip} \
           --cluster_domain=${cluster_domain_suffix} \

azure/container-linux/kubernetes/workers/workers.tf

@@ -111,6 +111,7 @@ data "template_file" "worker-config" {
     ssh_authorized_key     = var.ssh_authorized_key
     cluster_dns_service_ip = cidrhost(var.service_cidr, 10)
     cluster_domain_suffix  = var.cluster_domain_suffix
+    cgroup_driver          = local.flavor == "flatcar" && local.channel == "edge" ? "systemd" : "cgroupfs"
     node_labels            = join(",", var.node_labels)
   }
 }