Experimental Feature: Ignition Bootstrap Config (alpha)
The default configuration engine for bootstrapping workload cluster machines is cloud-init. Ignition is an alternative engine used by Linux distributions such as Flatcar Container Linux and Fedora CoreOS and therefore should be used when choosing an Ignition-based distribution as the underlying OS for workload clusters.
This guide explains how to deploy an AWS workload cluster using Ignition.
- kubectl installed locally
- clusterawsadm installed locally - download from the releases page of the AWS provider
- kind and Docker installed locally (when using kind to create a management cluster)
Configure a management cluster
Follow this section of the quick start guide to deploy a Kubernetes cluster or connect to an existing one.
Follow this section of the quick start guide to install
Initialize the management cluster
Before workload clusters can be deployed, Cluster API components must be deployed to the management cluster.
Initialize the management cluster:
export AWS_REGION=us-east-1 export AWS_ACCESS_KEY_ID=AKIAIOSFODNN7EXAMPLE export AWS_SECRET_ACCESS_KEY=wJalrXUtnFEMI/K7MDENG/bPxRfiCYEXAMPLEKEY # Workload clusters need to call the AWS API as part of their normal operation. # The following command creates a CloudFormation stack which provisions the # necessary IAM resources to be used by workload clusters. clusterawsadm bootstrap iam create-cloudformation-stack # The management cluster needs to call the AWS API in order to manage cloud # resources for workload clusters. The following command tells clusterctl to # store the AWS credentials provided before in a Kubernetes secret where they # can be retrieved by the AWS provider running on the management cluster. export AWS_B64ENCODED_CREDENTIALS=$(clusterawsadm bootstrap credentials encode-as-profile) # Enable the feature gates controlling Ignition bootstrap. export EXP_KUBEADM_BOOTSTRAP_FORMAT_IGNITION=true # Used by the kubeadm bootstrap provider export EXP_BOOTSTRAP_FORMAT_IGNITION=true # Used by the AWS provider # Initialize the management cluster. clusterctl init --infrastructure aws
Generate a workload cluster configuration
# Deploy the workload cluster in the following AWS region. export AWS_REGION=us-east-1 # Authorize the following SSH public key on cluster nodes. export AWS_SSH_KEY_NAME=my-key # Ignition bootstrap data needs to be stored in an S3 bucket so that nodes can # read them at boot time. Store Ignition bootstrap data in the following bucket. export AWS_S3_BUCKET_NAME=my-bucket # Set the EC2 machine size for controllers and workers. export AWS_CONTROL_PLANE_MACHINE_TYPE=t3a.small export AWS_NODE_MACHINE_TYPE=t3a.small clusterctl generate cluster ignition-cluster \ --from https://github.com/kubernetes-sigs/cluster-api-provider-aws/blob/main/templates/cluster-template-flatcar.yaml \ --kubernetes-version v1.22.2 \ --worker-machine-count 2 \ > ignition-cluster.yaml
Apply the workload cluster
kubectl apply -f ignition-cluster.yaml
Wait for the control plane of the workload cluster to become initialized:
kubectl get kubeadmcontrolplane ignition-cluster-control-plane
This could take a while. When the control plane is initialized, the
INITIALIZED field should be
NAME CLUSTER INITIALIZED API SERVER AVAILABLE REPLICAS READY UPDATED UNAVAILABLE AGE VERSION ignition-cluster-control-plane ignition-cluster true 1 1 1 7m7s v1.22.2
Connect to the workload cluster
Generate a kubeconfig for the workload cluster:
clusterctl get kubeconfig ignition-cluster > ./kubeconfig
kubectl to use the generated kubeconfig:
Verify connectivity with the workload cluster’s API server:
Kubernetes control plane is running at https://ignition-cluster-apiserver-284992524.us-east-1.elb.amazonaws.com:6443 CoreDNS is running at https://ignition-cluster-apiserver-284992524.us-east-1.elb.amazonaws.com:6443/api/v1/namespaces/kube-system/services/kube-dns:dns/proxy To further debug and diagnose cluster problems, use 'kubectl cluster-info dump'.
Deploy a CNI plugin
A CNI plugin must be deployed to the workload cluster for the cluster to become ready. We use Calico here, however other CNI plugins could be used, too.
kubectl apply -f https://docs.projectcalico.org/v3.20/manifests/calico.yaml
Ensure all cluster nodes become ready:
kubectl get nodes
NAME STATUS ROLES AGE VERSION ip-10-0-122-154.us-east-1.compute.internal Ready control-plane,master 14m v1.22.2 ip-10-0-127-59.us-east-1.compute.internal Ready <none> 13m v1.22.2 ip-10-0-89-169.us-east-1.compute.internal Ready <none> 13m v1.22.2
Delete the workload cluster (from a shell connected to the management cluster):
kubectl delete cluster ignition-cluster
Supported infrastructure providers
Cluster API has multiple infrastructure providers which can be used to deploy workload clusters.
The following infrastructure providers already have Ignition support:
Ignition support will be added to more providers in the future.