To ensure the security of communication between nodes, you must periodically check and renew the certificates of the master and worker nodes in a cluster, including the API server certificate and kubelet certificate. About two months before a certificate in an ACK dedicated cluster expires, a red button appears in the console to remind you to renew the certificate.
Usage notes
During the renewal process, the following system components are restarted: kube-apiserver, kube-controller-manager, and kube-scheduler. If your business logic is strongly reliant on these system components, make sure that your businesses will not be interrupted before you start. We recommend that you renew certificates during off-peak hours.
It requires about 5 to 10 minutes to complete the renewal process. The actual time cost depends on the number of nodes in the cluster. After the certificate is renewed, its validity period is extended by five years.
Backup
Node type | Backup content |
Master | Note If /var/lib/kubelet/pki is empty or you have no business-critical data, backup is not required. |
Worker | Note If /var/lib/kubelet/pki/* is empty or you have no business-critical data, backup is not required. |
Renew certificates
Table 1. Master nodes
Certificate or conf filename | Path | Validity period |
apiserver.crt apiserver.key
| /etc/kubernetes/pki | The initial validity period is 10 years. The validity period is extended by five years after renewal. |
| /etc/kubernetes/pki | The initial validity period is 10 years. The validity period is extended by five years after renewal. |
front-proxy-client.crt front-proxy-client.key
| /etc/kubernetes/pki | The initial validity period is 10 years. The validity period is extended by five years after renewal. |
dashboard.crt dashboard.key
| /etc/kubernetes/pki/dashboard | The initial validity period is 10 years. The validity period is extended by five years after renewal. |
Note If the kubelet.key file does not exist, renewal is not required. You can still use the cluster after kubelet.crt and kubelet.key expire.
| /var/lib/kubelet/pki Note If this path is empty, renewal is not required. | The initial validity period is 10 years. The validity period is extended by five years after renewal. |
admin.conf | /etc/kubernetes | The initial validity period is 10 years. The validity period is extended by five years after renewal. |
kube.conf | /etc/kubernetes | The initial validity period is 10 years. The validity period is extended by five years after renewal. |
controller-manager.conf | /etc/kubernetes | The initial validity period is 10 years. The validity period is extended by five years after renewal. |
scheduler.conf | /etc/kubernetes | The initial validity period is 10 years. The validity period is extended by five years after renewal. |
kubelet.conf | /etc/kubernetes | The initial validity period is 10 years. The validity period is extended by five years after renewal. |
config | ~/.kube/ | The initial validity period is 10 years. The validity period is extended by five years after renewal. |
Note If the kubelet-client.key file does not exist, renewal is not required. | /var/lib/kubelet/pki Note If this path is empty, renewal is not required. | The initial validity period is one year. When the certificate is about to expire, it is automatically renewed and the validity period is extended by one year. |
Table 2. Worker nodes
Certificate or conf filename | Path | Validity period |
Note If the kubelet.key file does not exist, renewal is not required. You can still use the cluster after kubelet.crt and kubelet.key expire.
| /var/lib/kubelet/pki Note If this path is empty, renewal is not required. | The initial validity period is 10 years. The validity period is extended by five years after renewal. |
Note If the kubelet-client.key file does not exist, renewal is not required. | /var/lib/kubelet/pki Note If this path is empty, renewal is not required. | The initial validity period is one year. When the certificate is about to expire, it is automatically renewed and the validity period is extended by one year. |
kubelet.conf | /etc/kubernetes | The initial validity period is 10 years. The validity period is extended by five years after renewal. |
Elastic Compute Service (ECS)
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