Chapter 3. Restarting the cluster gracefully This document describes the process to restart your cluster after a graceful shutdown. Even though the cluster is expected to be functional after the restart, the cluster might not recover due to unexpected conditions, for example: etcd data corruption during shutdown Node failure due to hardware Network connectivity issues If your cluster fails to recover, follow the steps to restore to a cluster state . 3.1. Prerequisites You have gracefully shut down your cluster . 3.2. Restarting the cluster You can restart your cluster after it has been shut down gracefully. Prerequisites You have access to the cluster as a user with the cluster-admin role. This procedure assumes that you gracefully shut down the cluster. Procedure Power on any cluster dependencies, such as external storage or an LDAP server. Start all cluster machines. Use the appropriate method for your cloud environment to start the machines, for example, from your cloud provider's web console. Wait approximately 10 minutes before continuing to check the status of control plane nodes (also known as the master nodes). Verify that all control plane nodes are ready. USD oc get nodes -l node-role.kubernetes.io/master The control plane nodes are ready if the status is Ready , as shown in the following output: NAME STATUS ROLES AGE VERSION ip-10-0-168-251.ec2.internal Ready master 75m v1.20.0 ip-10-0-170-223.ec2.internal Ready master 75m v1.20.0 ip-10-0-211-16.ec2.internal Ready master 75m v1.20.0 If the control plane nodes are not ready, then check whether there are any pending certificate signing requests (CSRs) that must be approved. Get the list of current CSRs: USD oc get csr Review the details of a CSR to verify that it is valid: USD oc describe csr <csr_name> 1 1 <csr_name> is the name of a CSR from the list of current CSRs. Approve each valid CSR: USD oc adm certificate approve <csr_name> After the control plane nodes are ready, verify that all worker nodes are ready. USD oc get nodes -l node-role.kubernetes.io/worker The worker nodes are ready if the status is Ready , as shown in the following output: NAME STATUS ROLES AGE VERSION ip-10-0-179-95.ec2.internal Ready worker 64m v1.20.0 ip-10-0-182-134.ec2.internal Ready worker 64m v1.20.0 ip-10-0-250-100.ec2.internal Ready worker 64m v1.20.0 If the worker nodes are not ready, then check whether there are any pending certificate signing requests (CSRs) that must be approved. Get the list of current CSRs: USD oc get csr Review the details of a CSR to verify that it is valid: USD oc describe csr <csr_name> 1 1 <csr_name> is the name of a CSR from the list of current CSRs. Approve each valid CSR: USD oc adm certificate approve <csr_name> Verify that the cluster started properly. Check that there are no degraded cluster Operators. USD oc get clusteroperators Check that there are no cluster Operators with the DEGRADED condition set to True . NAME VERSION AVAILABLE PROGRESSING DEGRADED SINCE authentication 4.7.0 True False False 59m cloud-credential 4.7.0 True False False 85m cluster-autoscaler 4.7.0 True False False 73m config-operator 4.7.0 True False False 73m console 4.7.0 True False False 62m csi-snapshot-controller 4.7.0 True False False 66m dns 4.7.0 True False False 76m etcd 4.7.0 True False False 76m ... Check that all nodes are in the Ready state: USD oc get nodes Check that the status for all nodes is Ready . NAME STATUS ROLES AGE VERSION ip-10-0-168-251.ec2.internal Ready master 82m v1.20.0 ip-10-0-170-223.ec2.internal Ready master 82m v1.20.0 ip-10-0-179-95.ec2.internal Ready worker 70m v1.20.0 ip-10-0-182-134.ec2.internal Ready worker 70m v1.20.0 ip-10-0-211-16.ec2.internal Ready master 82m v1.20.0 ip-10-0-250-100.ec2.internal Ready worker 69m v1.20.0 If the cluster did not start properly, you might need to restore your cluster using an etcd backup. Additional resources See Restoring to a cluster state for how to use an etcd backup to restore if your cluster failed to recover after restarting.

Commands:
oc get nodes -l node-role.kubernetes.io/master
NAME STATUS ROLES AGE VERSION ip-10-0-168-251.ec2.internal Ready master 75m v1.20.0 ip-10-0-170-223.ec2.internal Ready master 75m v1.20.0 ip-10-0-211-16.ec2.internal Ready master 75m v1.20.0
oc get csr
oc describe csr <csr_name> 1
oc adm certificate approve <csr_name>
oc get nodes -l node-role.kubernetes.io/worker
NAME STATUS ROLES AGE VERSION ip-10-0-179-95.ec2.internal Ready worker 64m v1.20.0 ip-10-0-182-134.ec2.internal Ready worker 64m v1.20.0 ip-10-0-250-100.ec2.internal Ready worker 64m v1.20.0
oc get csr
oc describe csr <csr_name> 1
oc adm certificate approve <csr_name>
oc get clusteroperators
NAME VERSION AVAILABLE PROGRESSING DEGRADED SINCE authentication 4.7.0 True False False 59m cloud-credential 4.7.0 True False False 85m cluster-autoscaler 4.7.0 True False False 73m config-operator 4.7.0 True False False 73m console 4.7.0 True False False 62m csi-snapshot-controller 4.7.0 True False False 66m dns 4.7.0 True False False 76m etcd 4.7.0 True False False 76m
oc get nodes
NAME STATUS ROLES AGE VERSION ip-10-0-168-251.ec2.internal Ready master 82m v1.20.0 ip-10-0-170-223.ec2.internal Ready master 82m v1.20.0 ip-10-0-179-95.ec2.internal Ready worker 70m v1.20.0 ip-10-0-182-134.ec2.internal Ready worker 70m v1.20.0 ip-10-0-211-16.ec2.internal Ready master 82m v1.20.0 ip-10-0-250-100.ec2.internal Ready worker 69m v1.20.0