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Cluster API Provider RKE2

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What is Cluster API Provider RKE2

The Cluster API brings declarative, Kubernetes-style APIs to cluster creation, configuration and management.

Cluster API Provider RKE2 is a combination of 2 provider types, a Cluster API Control Plane Provider for provisioning Kubernetes control plane nodes and a Cluster API Bootstrap Provider for bootstrapping Kubernetes on a machine where RKE2 is used as the Kubernetes distro.

Getting Started

Cluster API Provider RKE2 is compliant with the clusterctl contract, which means that clusterctl simplifies its deployment to the CAPI Management Cluster. In this Getting Started guide, we will be using the RKE2 Provider with the docker provider (also called CAPD).

Management Cluster

In order to use this provider, you need to have a management cluster available to you and have your current KUBECONFIG context set to talk to that cluster. If you do not have a cluster available to you, you can create a kind cluster. These are the steps needed to achieve that:

  1. Ensure kind is installed (https://kind.sigs.k8s.io/docs/user/quick-start/#installation)
  2. Create a special kind configuration file if you intend to use the Docker infrastructure provider:
cat > kind-cluster-with-extramounts.yaml <<EOF
kind: Cluster
apiVersion: kind.x-k8s.io/v1alpha4
name: capi-test
nodes:
- role: control-plane
  extraMounts:
    - hostPath: /var/run/docker.sock
      containerPath: /var/run/docker.sock
EOF
  1. Run the following command to create a local kind cluster:
kind create cluster --config kind-cluster-with-extramounts.yaml
  1. Check your newly created kind cluster :
kubectl cluster-info

and get a similar result to this:

Kubernetes control plane is running at https://127.0.0.1:40819
CoreDNS is running at https://127.0.0.1:40819/api/v1/namespaces/kube-system/services/kube-dns:dns/proxy

To further debug and diagnose cluster problems, use 'kubectl cluster-info dump'.

Setting up clusterctl

CAPI >= v1.6.0

No additional steps are required and you can install the RKE2 provider with clusterctl directly:

clusterctl init --bootstrap rke2 --control-plane rke2 --infrastructure docker

CAPI < v1.6.0

With CAPI & clusterctl versions less than v1.6.0 you need a specific configuration. To do this create a file called clusterctl.yaml in the $HOME/.cluster-api folder with the following content:

providers:
  - name: "rke2"
    url: "https://github.com/rancher/cluster-api-provider-rke2/releases/v0.1.1/bootstrap-components.yaml"
    type: "BootstrapProvider"
  - name: "rke2"
    url: "https://github.com/rancher/cluster-api-provider-rke2/releases/v0.1.1/control-plane-components.yaml"
    type: "ControlPlaneProvider"

NOTE: Due to some issue related to how CAPD creates Load Balancer healthchecks, it is necessary to use a fork of CAPD by providing in the above configuration file the following :

  - name: "docker"
    url: "https://github.com/belgaied2/cluster-api/releases/v1.3.3-cabpr-fix/infrastructure-components.yaml"
    type: "InfrastructureProvider"

This configuration tells clusterctl where to look for provider manifests in order to deploy provider components in the management cluster.

The next step is to run the clusterctl init command:

clusterctl init --bootstrap rke2 --control-plane rke2 --infrastructure docker:v1.3.3-cabpr-fix

This should output something similar to the following:

Fetching providers
Installing cert-manager Version="v1.10.1"
Waiting for cert-manager to be available...
Installing Provider="cluster-api" Version="v1.3.3" TargetNamespace="capi-system"
Installing Provider="bootstrap-rke2" Version="v0.1.0-alpha.1" TargetNamespace="rke2-bootstrap-system"
Installing Provider="control-plane-rke2" Version="v0.1.0-alpha.1" TargetNamespace="rke2-control-plane-system"

Your management cluster has been initialized successfully!

You can now create your first workload cluster by running the following:

  clusterctl generate cluster [name] --kubernetes-version [version] | kubectl apply -f -

Create a workload cluster

There are some sample cluster templates available under the samples folder. This section assumes you are using CAPI v1.6.0 or higher.

For this Getting Started section, we will be using the docker samples available under samples/docker/oneline-default folder. This folder contains a YAML template file called rke2-sample.yaml which contains environment variable placeholders which can be substituted using the envsubst tool. We will use clusterctl to generate the manifests from these template files. Set the following environment variables:

  • CABPR_NAMESPACE
  • CLUSTER_NAME
  • CABPR_CP_REPLICAS
  • CABPR_WK_REPLICAS
  • KUBERNETES_VERSION

for example:

export CABPR_NAMESPACE=example
export CLUSTER_NAME=capd-rke2-test
export CABPR_CP_REPLICAS=3
export CABPR_WK_REPLICAS=2
export KUBERNETES_VERSION=v1.24.6

The next step is to substitue the values in the YAML using the following commands:

cat rke2-sample.yaml | clusterctl generate yaml > rke2-docker-example.yaml

At this moment, you can take some time to study the resulting YAML, then you can apply it to the management cluster:

kubectl apply -f rke2-docker-example.yaml

and see the following output:

namespace/example created
cluster.cluster.x-k8s.io/rke2-test created
dockercluster.infrastructure.cluster.x-k8s.io/rke2-test created
rke2controlplane.controlplane.cluster.x-k8s.io/rke2-test-control-plane created
dockermachinetemplate.infrastructure.cluster.x-k8s.io/controlplane created
machinedeployment.cluster.x-k8s.io/worker-md-0 created
dockermachinetemplate.infrastructure.cluster.x-k8s.io/worker created
rke2configtemplate.bootstrap.cluster.x-k8s.io/rke2-test-agent created

Checking the workload cluster

After waiting several minutes, you can check the state of CAPI machines, by running the following command:

kubectl get machine -n example

and you should see output similar to the following:

NAME                                 CLUSTER          NODENAME                                      PROVIDERID                                               PHASE     AGE     VERSION
capd-rke2-test-control-plane-4njnd   capd-rke2-test   capd-rke2-test-control-plane-4njnd            docker:////capd-rke2-test-control-plane-4njnd            Running   5m18s   v1.24.6
capd-rke2-test-control-plane-rccsk   capd-rke2-test   capd-rke2-test-control-plane-rccsk            docker:////capd-rke2-test-control-plane-rccsk            Running   3m1s    v1.24.6
capd-rke2-test-control-plane-v5g8v   capd-rke2-test   capd-rke2-test-control-plane-v5g8v            docker:////capd-rke2-test-control-plane-v5g8v            Running   8m4s    v1.24.6
worker-md-0-6d4944f5b6-k5xxw         capd-rke2-test   capd-rke2-test-worker-md-0-6d4944f5b6-k5xxw   docker:////capd-rke2-test-worker-md-0-6d4944f5b6-k5xxw   Running   8m6s    v1.24.6
worker-md-0-6d4944f5b6-qjbjh         capd-rke2-test   capd-rke2-test-worker-md-0-6d4944f5b6-qjbjh   docker:////capd-rke2-test-worker-md-0-6d4944f5b6-qjbjh   Running   8m6s    v1.24.6

You can now get the kubeconfig file for the workload cluster using :

clusterctl get kubeconfig capd-rke2-test -n example > ~/capd-rke2-test-kubeconfig.yaml
export KUBECONFIG=~/capd-rke2-test-kubeconfig.yaml

and query the newly created cluster using:

kubectl cluster-info

and see output like this:

Kubernetes control plane is running at https://172.18.0.5:6443
CoreDNS is running at https://172.18.0.5:6443/api/v1/namespaces/kube-system/services/rke2-coredns-rke2-coredns:udp-53/proxy

To further debug and diagnose cluster problems, use 'kubectl cluster-info dump'.

🎉 CONGRATULATIONS ! 🎉 You created your first RKE2 cluster with CAPD as an infrastructure provider.

Using ClusterClass for cluster creation

This provider supports using ClusterClass, a Cluster API feature that implements an extra level of abstraction on top of the existing Cluster API functionality. The ClusterClass object is used to define a collection of template resources (control plane and machine deployment) which are used to generate one or more clusters of the same flavor.

If you are interested in leveraging this functionality, you can refer to the examples here:

As with other sample templates, you will need to set a number environment variables:

  • CLUSTER_NAME
  • CABPR_CP_REPLICAS
  • CABPR_WK_REPLICAS
  • KUBERNETES_VERSION
  • KIND_IP

for example:

export CLUSTER_NAME=capd-rke2-clusterclass
export CABPR_CP_REPLICAS=3
export CABPR_WK_REPLICAS=2
export KUBERNETES_VERSION=v1.25.11
export KIND_IP=192.168.20.20

Remember that, since we are using Kind, the value of KIND_IP must be an IP address in the range of the kind network. You can check the range Docker assigns to this network by inspecting it:

docker network inspect kind

The next step is to substitue the values in the YAML using the following commands:

cat clusterclass-quick-start.yaml | clusterctl generate yaml > clusterclass-example.yaml

At this moment, you can take some time to study the resulting YAML, then you can apply it to the management cluster:

kubectl apply -f clusterclass-example.yaml

This will create a new ClusterClass template that can be used to provision one or multiple workload clusters of the same flavor. To do so, you can follow the same procedure and substitute the values in the YAML for the cluster definition:

cat rke2-sample.yaml | clusterctl generate yaml > rke2-clusterclass-example.yaml

And then apply the resulting YAML file to create a cluster from the existing ClusterClass.

kubectl apply -f rke2-clusterclass-example.yaml

Testing the DEV main branch

These instructions are for development purposes initially and will be changed in the future for user facing instructions.

  1. Clone the Cluster API Repo into the GOPATH

Why clone into the GOPATH? There have been historic issues with code generation tools when they are run outside the go path

  1. Fork the Cluster API Provider RKE2 repo
  2. Clone your new repo into the GOPATH (i.e. ~/go/src/github.com/yourname/cluster-api-provider-rke2)
  3. Ensure Tilt and kind are installed
  4. Create a tilt-settings.json file in the root of your forked/cloned cluster-api directory.
  5. Add the following contents to the file (replace "yourname" with your github account name):
{
    "default_registry": "ghcr.io/yourname",
    "provider_repos": ["../../github.com/yourname/cluster-api-provider-rke2"],
    "enable_providers": ["docker", "rke2-bootstrap", "rke2-control-plane"],
    "kustomize_substitutions": {
        "EXP_MACHINE_POOL": "true",
        "EXP_CLUSTER_RESOURCE_SET": "true"
    },
    "extra_args": {
        "rke2-bootstrap": ["--v=4"],
        "rke2-control-plane": ["--v=4"],
        "core": ["--v=4"]
    },
    "debug": {
        "rke2-bootstrap": {
            "continue": true,
            "port": 30001
        },
        "rke2-control-plane": {
            "continue": true,
            "port": 30002
        }
    }
}

NOTE: Until this bug merged in CAPI you will have to make the changes locally to your clone of CAPI.

  1. Open another terminal (or pane) and go to the cluster-api directory.
  2. Run the following to create a configuration for kind:
cat > kind-cluster-with-extramounts.yaml <<EOF
kind: Cluster
apiVersion: kind.x-k8s.io/v1alpha4
name: capi-test
nodes:
- role: control-plane
  extraMounts:
    - hostPath: /var/run/docker.sock
      containerPath: /var/run/docker.sock
EOF

NOTE: if you are using Docker Desktop v4.13 or above then you will you will encounter issues from here. Until a permanent solution is found its recommended you use v4.12

  1. Run the following command to create a local kind cluster:
kind create cluster --config kind-cluster-with-extramounts.yaml
  1. Now start tilt by running the following:
tilt up
  1. Press the space key to see the Tilt web ui and check that everything goes green.

Known Issues

When using CAPD < v1.6.0 unmodified, Cluster creation is stuck after first node and API is not reachable

If you use docker as your infrastructure provider without any modification, Cluster creation will stall after provisioning the first node, and the API will not be available using the LB address. This is caused by Load Balancer configuration used in CAPD which is not compatible with RKE2. Therefore, it is necessary to use our own fork of v1.3.3 by using a specific clusterctl configuration.

Get in contact

You can get in contact with us via the #capbr channel on the Rancher Users Slack.