Chapter 3. Restarting the cluster gracefully

Procedure

1. Turn on the control plane nodes.

   • If you are using the

     admin.kubeconfig

     from the cluster installation and the API virtual IP address (VIP) is up, complete the following steps:
     1. Set the

        KUBECONFIG

        environment variable to the

        admin.kubeconfig

        path.

     2. For each control plane node in the cluster, run the following command:

        $ oc adm uncordon <node>

   • If you do not have access to your

     admin.kubeconfig

     credentials, complete the following steps:
     1. Use SSH to connect to a control plane node.
     2. Copy the

        localhost-recovery.kubeconfig

        file to the

        /root

        directory.

     3. Use that file to run the following command for each control plane node in the cluster:

        $ oc adm uncordon <node>

2. Power on any cluster dependencies, such as external storage or an LDAP server.

3. 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.

4. Verify that all control plane nodes are ready.

   $ 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   v1.25.0
   ip-10-0-170-223.ec2.internal   Ready    master   75m   v1.25.0
   ip-10-0-211-16.ec2.internal    Ready    master   75m   v1.25.0

5. If the control plane nodes are not ready, then check whether there are any pending certificate signing requests (CSRs) that must be approved.

   1. Get the list of current CSRs:

      $ oc get csr

   2. Review the details of a CSR to verify that it is valid:

      $ oc describe csr <csr_name> 

      1

      1

      <csr_name> is the name of a CSR from the list of current CSRs.

   3. Approve each valid CSR:

      $ oc adm certificate approve <csr_name>

6. After the control plane nodes are ready, verify that all worker nodes are ready.

   $ 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   v1.25.0
   ip-10-0-182-134.ec2.internal   Ready    worker   64m   v1.25.0
   ip-10-0-250-100.ec2.internal   Ready    worker   64m   v1.25.0

7. If the worker nodes are not ready, then check whether there are any pending certificate signing requests (CSRs) that must be approved.

   1. Get the list of current CSRs:

      $ oc get csr

   2. Review the details of a CSR to verify that it is valid:

      $ oc describe csr <csr_name> 

      1

      1

      <csr_name> is the name of a CSR from the list of current CSRs.

   3. Approve each valid CSR:

      $ oc adm certificate approve <csr_name>

8. Verify that the cluster started properly.

   1. Check that there are no degraded cluster Operators.

      $ oc get clusteroperators

      Check that there are no cluster Operators with the

      DEGRADED

      condition set to

      True

      .

      NAME                                       VERSION   AVAILABLE   PROGRESSING   DEGRADED   SINCE
      authentication                             4.12.0    True        False         False      59m
      cloud-credential                           4.12.0    True        False         False      85m
      cluster-autoscaler                         4.12.0    True        False         False      73m
      config-operator                            4.12.0    True        False         False      73m
      console                                    4.12.0    True        False         False      62m
      csi-snapshot-controller                    4.12.0    True        False         False      66m
      dns                                        4.12.0    True        False         False      76m
      etcd                                       4.12.0    True        False         False      76m
      ...

   2. Check that all nodes are in the

      Ready

      state:

      $ 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   v1.25.0
      ip-10-0-170-223.ec2.internal   Ready    master   82m   v1.25.0
      ip-10-0-179-95.ec2.internal    Ready    worker   70m   v1.25.0
      ip-10-0-182-134.ec2.internal   Ready    worker   70m   v1.25.0
      ip-10-0-211-16.ec2.internal    Ready    master   82m   v1.25.0
      ip-10-0-250-100.ec2.internal   Ready    worker   69m   v1.25.0

      If the cluster did not start properly, you might need to restore your cluster using an etcd backup.

9. After the control plane and worker nodes are ready, mark all the nodes in the cluster as schedulable. Run the following command:

   for node in $(oc get nodes -o jsonpath='{.items[*].metadata.name}'); do echo ${node} ; oc adm uncordon ${node} ; done