Add ignition support

[barbacbd]

/kind feature

Describe the solution you'd like
[A clear and concise description of what you want to happen.]

Similar to the AWS provider, ignition support should be added for control plane and bootstrap nodes.

Ignition data can be supplied as []byte. The data should be placed in a storage object inside of a bucket. The CAPI GCP Provider will create the storage object and bucket. The name of the bucket should be unique but easily determined so that the user can reference the bucket if/when needed (i.e %s-bootstrap-ignition where the missing string is unique reference created by the user).

Anything else you would like to add:
[Miscellaneous information that will assist in solving the issue.]

1. Ignition Version: Default = 2.3 (only version to use for now)
2. This will provide the user the ability to create a signed url that points to the bucket instead of supplying a large data dump directly in the bucket. The signed url is also a way to provide other information such as proxies.
3. It will be up to the user to destroy the bucket and the object.

[tormath1]

I started to have a look for Flatcar support (#540). Ignition should work with export EXP_KUBEADM_BOOTSTRAP_FORMAT_IGNITION=true before creating the management cluster.

This template might work using vanilla Flatcar images (without image-builder):

---
apiVersion: cluster.x-k8s.io/v1beta1
kind: Cluster
metadata:
  name: "${CLUSTER_NAME}"
spec:
  clusterNetwork:
    pods:
      cidrBlocks: ["192.168.0.0/16"]
  infrastructureRef:
    apiVersion: infrastructure.cluster.x-k8s.io/v1beta1
    kind: GCPCluster
    name: "${CLUSTER_NAME}"
  controlPlaneRef:
    kind: KubeadmControlPlane
    apiVersion: controlplane.cluster.x-k8s.io/v1beta1
    name: "${CLUSTER_NAME}-control-plane"
---
apiVersion: infrastructure.cluster.x-k8s.io/v1beta1
kind: GCPCluster
metadata:
  name: "${CLUSTER_NAME}"
spec:
  project: "${GCP_PROJECT}"
  region: "${GCP_REGION}"
  network:
    name: "${GCP_NETWORK_NAME}"
---
kind: KubeadmControlPlane
apiVersion: controlplane.cluster.x-k8s.io/v1beta1
metadata:
  name: "${CLUSTER_NAME}-control-plane"
spec:
  replicas: ${CONTROL_PLANE_MACHINE_COUNT}
  machineTemplate:
    infrastructureRef:
      kind: GCPMachineTemplate
      apiVersion: infrastructure.cluster.x-k8s.io/v1beta1
      name: "${CLUSTER_NAME}-control-plane"
  kubeadmConfigSpec:
    files: []
    format: ignition
    ignition:
      containerLinuxConfig:
        additionalConfig: |
          storage:
            links:
              - path: /etc/extensions/kubernetes.raw
                hard: false
                target: /opt/extensions/kubernetes/kubernetes-${KUBERNETES_VERSION}-x86-64.raw
            files:
              - path: /etc/sysupdate.kubernetes.d/kubernetes-${KUBERNETES_VERSION%.*}.conf
                mode: 0644
                contents:
                  remote:
                    url: https://github.com/flatcar/sysext-bakery/releases/download/latest/kubernetes-${KUBERNETES_VERSION%.*}.conf
              - path: /etc/sysupdate.d/noop.conf
                mode: 0644
                contents:
                  remote:
                    url: https://github.com/flatcar/sysext-bakery/releases/download/latest/noop.conf
              - path: /opt/extensions/kubernetes/kubernetes-${KUBERNETES_VERSION}-x86-64.raw
                contents:
                  remote:
                    url: https://github.com/flatcar/sysext-bakery/releases/download/latest/kubernetes-${KUBERNETES_VERSION}-x86-64.raw
          systemd:
            units:
              - name: systemd-sysupdate.service
                dropins:
                  - name: kubernetes.conf
                    contents: |
                      [Service]
                      ExecStartPre=/usr/bin/sh -c "readlink --canonicalize /etc/extensions/kubernetes.raw > /tmp/kubernetes"
                      ExecStartPre=/usr/lib/systemd/systemd-sysupdate -C kubernetes update
                      ExecStartPost=/usr/bin/sh -c "readlink --canonicalize /etc/extensions/kubernetes.raw > /tmp/kubernetes-new"
                      ExecStartPost=/usr/bin/sh -c "if ! cmp --silent /tmp/kubernetes /tmp/kubernetes-new; then touch /run/reboot-required; fi"
              - name: update-engine.service
                # Set this to 'false' if you want to enable Flatcar auto-update
                mask: ${FLATCAR_DISABLE_AUTO_UPDATE:=true}
              - name: locksmithd.service
                # NOTE: To coordinate the node reboot in this context, we recommend to use Kured.
                mask: true
              - name: systemd-sysupdate.timer
                # Set this to 'true' if you want to enable the Kubernetes auto-update.
                # NOTE: Only patches version will be pulled.
                enabled: false
              - name: [email protected]
                enabled: true
              - name: kubeadm.service
                enabled: true
                dropins:
                  - name: 10-flatcar.conf
                    contents: |
                      [Unit]
                      Requires=containerd.service coreos-metadata.service
                      After=containerd.service coreos-metadata.service
                      [Service]
                      EnvironmentFile=/run/metadata/flatcar
    initConfiguration:
      nodeRegistration:
        name: $${COREOS_GCE_HOSTNAME}
        kubeletExtraArgs:
          cloud-provider: gce
          feature-gates: "DisableCloudProviders=false,DisableKubeletCloudCredentialProviders=false"
    clusterConfiguration:
      apiServer:
        timeoutForControlPlane: 20m
        extraArgs:
          cloud-provider: gce
          feature-gates: "DisableCloudProviders=false,DisableKubeletCloudCredentialProviders=false"
      controllerManager:
        extraArgs:
          cloud-provider: gce
          feature-gates: "DisableCloudProviders=false,DisableKubeletCloudCredentialProviders=false"
          allocate-node-cidrs: "false"
    joinConfiguration:
      nodeRegistration:
        name: $${COREOS_GCE_HOSTNAME}
        kubeletExtraArgs:
          cloud-provider: gce
          feature-gates: "DisableCloudProviders=false,DisableKubeletCloudCredentialProviders=false"
    preKubeadmCommands:
    - export COREOS_GCE_HOSTNAME=$${COREOS_GCE_HOSTNAME%.*}
    - envsubst < /etc/kubeadm.yml > /etc/kubeadm.yml.tmp
    - mv /etc/kubeadm.yml.tmp /etc/kubeadm.yml
  version: "${KUBERNETES_VERSION}"
---
kind: GCPMachineTemplate
apiVersion: infrastructure.cluster.x-k8s.io/v1beta1
metadata:
  name: "${CLUSTER_NAME}-control-plane"
spec:
  template:
    spec:
      instanceType: "${GCP_CONTROL_PLANE_MACHINE_TYPE}"
      image: "${IMAGE_ID}"
---
apiVersion: cluster.x-k8s.io/v1beta1
kind: MachineDeployment
metadata:
  name: "${CLUSTER_NAME}-md-0"
spec:
  clusterName: "${CLUSTER_NAME}"
  replicas: ${WORKER_MACHINE_COUNT}
  selector:
    matchLabels:
  template:
    spec:
      clusterName: "${CLUSTER_NAME}"
      version: "${KUBERNETES_VERSION}"
      bootstrap:
        configRef:
          name: "${CLUSTER_NAME}-md-0"
          apiVersion: bootstrap.cluster.x-k8s.io/v1beta1
          kind: KubeadmConfigTemplate
      infrastructureRef:
        name: "${CLUSTER_NAME}-md-0"
        apiVersion: infrastructure.cluster.x-k8s.io/v1beta1
        kind: GCPMachineTemplate
---
apiVersion: infrastructure.cluster.x-k8s.io/v1beta1
kind: GCPMachineTemplate
metadata:
  name: "${CLUSTER_NAME}-md-0"
spec:
  template:
    spec:
      instanceType: "${GCP_NODE_MACHINE_TYPE}"
      image: "${IMAGE_ID}"
---
apiVersion: bootstrap.cluster.x-k8s.io/v1beta1
kind: KubeadmConfigTemplate
metadata:
  name: "${CLUSTER_NAME}-md-0"
spec:
  template:
    spec:
      files: []
      format: ignition
      ignition:
        containerLinuxConfig:
          additionalConfig: |
            storage:
              links:
                - path: /etc/extensions/kubernetes.raw
                  hard: false
                  target: /opt/extensions/kubernetes/kubernetes-${KUBERNETES_VERSION}-x86-64.raw
              files:
                - path: /etc/sysupdate.kubernetes.d/kubernetes-${KUBERNETES_VERSION%.*}.conf
                  mode: 0644
                  contents:
                    remote:
                      url: https://github.com/flatcar/sysext-bakery/releases/download/latest/kubernetes-${KUBERNETES_VERSION%.*}.conf
                - path: /etc/sysupdate.d/noop.conf
                  mode: 0644
                  contents:
                    remote:
                      url: https://github.com/flatcar/sysext-bakery/releases/download/latest/noop.conf
                - path: /opt/extensions/kubernetes/kubernetes-${KUBERNETES_VERSION}-x86-64.raw
                  contents:
                    remote:
                      url: https://github.com/flatcar/sysext-bakery/releases/download/latest/kubernetes-${KUBERNETES_VERSION}-x86-64.raw
            systemd:
              units:
                - name: systemd-sysupdate.service
                  dropins:
                    - name: kubernetes.conf
                      contents: |
                        [Service]
                        ExecStartPre=/usr/bin/sh -c "readlink --canonicalize /etc/extensions/kubernetes.raw > /tmp/kubernetes"
                        ExecStartPre=/usr/lib/systemd/systemd-sysupdate -C kubernetes update
                        ExecStartPost=/usr/bin/sh -c "readlink --canonicalize /etc/extensions/kubernetes.raw > /tmp/kubernetes-new"
                        ExecStartPost=/usr/bin/sh -c "if ! cmp --silent /tmp/kubernetes /tmp/kubernetes-new; then touch /run/reboot-required; fi"
                - name: update-engine.service
                  # Set this to 'false' if you want to enable Flatcar auto-update
                  mask: ${FLATCAR_DISABLE_AUTO_UPDATE:=true}
                - name: locksmithd.service
                  # NOTE: To coordinate the node reboot in this context, we recommend to use Kured.
                  mask: true
                - name: systemd-sysupdate.timer
                  # Set this to 'true' if you want to enable the Kubernetes auto-update.
                  # NOTE: Only patches version will be pulled.
                  enabled: false
                - name: [email protected]
                  enabled: true
                - name: kubeadm.service
                  enabled: true
                  dropins:
                    - name: 10-flatcar.conf
                      contents: |
                        [Unit]
                        Requires=containerd.service coreos-metadata.service
                        After=containerd.service coreos-metadata.service
                        [Service]
                        EnvironmentFile=/run/metadata/flatcar
      joinConfiguration:
        nodeRegistration:
          name: $${COREOS_GCE_HOSTNAME}
          kubeletExtraArgs:
            cloud-provider: gce
            feature-gates: "DisableCloudProviders=false,DisableKubeletCloudCredentialProviders=false"
      preKubeadmCommands:
      - export COREOS_GCE_HOSTNAME=$${COREOS_GCE_HOSTNAME%.*}
      - envsubst < /etc/kubeadm.yml > /etc/kubeadm.yml.tmp
      - mv /etc/kubeadm.yml.tmp /etc/kubeadm.yml

but for now it fails on this:

cluster-api-provider-gcp/cloud/scope/machine.go

Lines 467 to 469 in 5938bd1

	if m.Machine.Spec.Bootstrap.DataSecretName == nil {
	return "", errors.New("error retrieving bootstrap data: linked Machine's bootstrap.dataSecretName is nil")
	}

- I have to investigate what's going on here.

(cc @AverageMarcus I know you were interested in the past for Flatcar support on this CAPI provider)