Certificate rotation

Certificates for external etcd and control plane nodes expire after 1 year in EKS Anywhere. EKS Anywhere automatically rotates these certificates when new machines are rolled out in the cluster. New machines are rolled out during cluster lifecycle operations such as upgrade. If you upgrade your cluster at least once a year, you do not have to manually rotate the cluster certificates.

This page shows the process for manually rotating certificates if you have not upgraded your cluster in 1 year.

The following table lists the cluster certificate files:

You can rotate certificates by following the steps given below. You cannot rotate the ca certificate because it is the root certificate. Note that the commands used for Bottlerocket nodes are different than those for Ubuntu and RHEL nodes.

External etcd nodes

If your cluster is using external etcd nodes, you need to renew the etcd node certificates first.

kubectl get etcdadmcluster -A

1. SSH into each etcd node and run the following commands. Etcd automatically detects the new certificates and deprecates its old certificates.

• Ubuntu or RHEL
• Bottlerocket

# backup certs
cd /etc/etcd
sudo cp -r pki pki.bak
sudo rm pki/*
sudo cp pki.bak/ca.* pki

# run certificates join phase to regenerate the deleted certificates
sudo etcdadm join phase certificates http://eks-a-etcd-dumb-url

# you would be in the admin container when you ssh to the Bottlerocket machine
# open a root shell
sudo sheltie

# pull the image
IMAGE_ID=$(apiclient get | apiclient exec admin jq -r '.settings["host-containers"]["kubeadm-bootstrap"].source')
ctr image pull ${IMAGE_ID}

# backup certs
cd /var/lib/etcd
cp -r pki pki.bak
rm pki/*
cp pki.bak/ca.* pki

# recreate certificates
ctr run \
--mount type=bind,src=/var/lib/etcd/pki,dst=/etc/etcd/pki,options=rbind:rw \
--net-host \
--rm \
${IMAGE_ID} tmp-cert-renew \
/opt/bin/etcdadm join phase certificates http://eks-a-etcd-dumb-url --init-system kubelet

2. Verify your etcd node is running correctly

• Ubuntu or RHEL
• Bottlerocket

sudo etcdctl --cacert=/etc/etcd/pki/ca.crt --cert=/etc/etcd/pki/etcdctl-etcd-client.crt --key=/etc/etcd/pki/etcdctl-etcd-client.key member list

ETCD_CONTAINER_ID=$(ctr -n k8s.io c ls | grep -w "etcd-io" | cut -d " " -f1)
ctr -n k8s.io t exec -t --exec-id etcd ${ETCD_CONTAINER_ID} etcdctl \
     --cacert=/var/lib/etcd/pki/ca.crt \
     --cert=/var/lib/etcd/pki/server.crt \
     --key=/var/lib/etcd/pki/server.key \
     member list

3. Repeat the above steps for all etcd nodes.

4. Save the api-server-etcd-client crt and key file as a Secret from one of the etcd nodes, so the key can be picked up by new control plane nodes. You will also need them when renewing the certificates on control plane nodes. See the Kubernetes documentation for details on editing Secrets.

kubectl edit secret ${cluster-name}-api-server-etcd-client -n eksa-system

Control plane nodes

When there are no external etcd nodes, you only need to rotate the certificates for control plane nodes, as etcd certificates are managed by kubeadm when there are no external etcd nodes.

1. SSH into each control plane node and run the following commands.

• Ubuntu or RHEL
• Bottlerocket

sudo kubeadm certs renew all

# you would be in the admin container when you ssh to the Bottlerocket machine
# open root shell
sudo sheltie

# pull the image
IMAGE_ID=$(apiclient get | apiclient exec admin jq -r '.settings["host-containers"]["kubeadm-bootstrap"].source')
ctr image pull ${IMAGE_ID}

# renew certs
# you may see missing etcd certs error, which is expected if you have external etcd nodes
ctr run \
--mount type=bind,src=/var/lib/kubeadm,dst=/var/lib/kubeadm,options=rbind:rw \
--mount type=bind,src=/var/lib/kubeadm,dst=/etc/kubernetes,options=rbind:rw \
--rm \
${IMAGE_ID} tmp-cert-renew \
/opt/bin/kubeadm certs renew all

2. Verify the certificates have been rotated.

• Ubuntu or RHEL
• Bottlerocket

sudo kubeadm certs check-expiration

# you may see missing etcd certs error, which is expected if you have external etcd nodes
ctr run \
--mount type=bind,src=/var/lib/kubeadm,dst=/var/lib/kubeadm,options=rbind:rw \
--mount type=bind,src=/var/lib/kubeadm,dst=/etc/kubernetes,options=rbind:rw \
--rm \
${IMAGE_ID} tmp-cert-renew \
/opt/bin/kubeadm certs check-expiration

3. If you have external etcd nodes, manually replace the api-server-etcd-client.crt and api-server-etcd-client.key file in /etc/kubernetes/pki (or /var/lib/kubeadm/pki in Bottlerocket) folder with the files you saved from any etcd node.

4. Restart static control plane pods.

   • For Ubuntu and RHEL: temporarily move all manifest files from /etc/kubernetes/manifests/ and wait for 20 seconds, then move the manifests back to this file location.

   • For Bottlerocket: re-enable the static pods:

   apiclient get | jq -r '.settings.kubernetes["static-pods"] | keys[]' | xargs -n 1 -I {} apiclient set settings.kubernetes.static-pods.{}.enabled=false 
   apiclient get | jq -r '.settings.kubernetes["static-pods"] | keys[]' | xargs -n 1 -I {} apiclient set settings.kubernetes.static-pods.{}.enabled=true`
   

   You can verify Pods restarting by running kubectl from your Admin machine.

5. Repeat the above steps for all control plane nodes.

You can similarly use the above steps to rotate a single certificate instead of all certificates.