2.4. Replacing the unhealthy etcd member

Procedure

1. Remove the unhealthy member.

   1. Choose a pod that is not on the affected node:

      In a terminal that has access to the cluster as a cluster-admin user, run the following command:

      $ oc get pods -n openshift-etcd | grep etcd

      Example output

      etcd-ip-10-0-131-183.ec2.internal                3/3     Running     0          123m
      etcd-ip-10-0-164-97.ec2.internal                 3/3     Running     0          123m
      etcd-ip-10-0-154-204.ec2.internal                3/3     Running     0          124m

   2. Connect to the running etcd container, passing in the name of a pod that is not on the affected node:

      In a terminal that has access to the cluster as a cluster-admin user, run the following command:

      $ oc rsh -n openshift-etcd etcd-ip-10-0-154-204.ec2.internal

   3. View the member list:

      sh-4.2# etcdctl member list -w table

      Example output

      +------------------+---------+------------------------------+---------------------------+---------------------------+
      |        ID        | STATUS  |             NAME             |        PEER ADDRS         |       CLIENT ADDRS        |
      +------------------+---------+------------------------------+---------------------------+---------------------------+
      | 6fc1e7c9db35841d | started | ip-10-0-131-183.ec2.internal | https://10.0.131.183:2380 | https://10.0.131.183:2379 |
      | 757b6793e2408b6c | started |  ip-10-0-164-97.ec2.internal |  https://10.0.164.97:2380 |  https://10.0.164.97:2379 |
      | ca8c2990a0aa29d1 | started | ip-10-0-154-204.ec2.internal | https://10.0.154.204:2380 | https://10.0.154.204:2379 |
      +------------------+---------+------------------------------+---------------------------+---------------------------+

      Take note of the ID and the name of the unhealthy etcd member, because these values are needed later in the procedure.

   4. Remove the unhealthy etcd member by providing the ID to the etcdctl member remove command:

      sh-4.2# etcdctl member remove 6fc1e7c9db35841d

      Example output

      Member 6fc1e7c9db35841d removed from cluster baa565c8919b060e

   5. View the member list again and verify that the member was removed:

      sh-4.2# etcdctl member list -w table

      Example output

      +------------------+---------+------------------------------+---------------------------+---------------------------+
      |        ID        | STATUS  |             NAME             |        PEER ADDRS         |       CLIENT ADDRS        |
      +------------------+---------+------------------------------+---------------------------+---------------------------+
      | 757b6793e2408b6c | started |  ip-10-0-164-97.ec2.internal |  https://10.0.164.97:2380 |  https://10.0.164.97:2379 |
      | ca8c2990a0aa29d1 | started | ip-10-0-154-204.ec2.internal | https://10.0.154.204:2380 | https://10.0.154.204:2379 |
      +------------------+---------+------------------------------+---------------------------+---------------------------+

      You can now exit the node shell.

2. Remove the old secrets for the unhealthy etcd member that was removed.

   1. List the secrets for the unhealthy etcd member that was removed.

      $ oc get secrets -n openshift-etcd | grep ip-10-0-131-183.ec2.internal 1

      1

      Pass in the name of the unhealthy etcd member that you took note of earlier in this procedure.

      There is a peer, serving, and metrics secret as shown in the following output:

      Example output

      etcd-peer-ip-10-0-131-183.ec2.internal              kubernetes.io/tls                     2      47m
      etcd-serving-ip-10-0-131-183.ec2.internal           kubernetes.io/tls                     2      47m
      etcd-serving-metrics-ip-10-0-131-183.ec2.internal   kubernetes.io/tls                     2      47m

   2. Delete the secrets for the unhealthy etcd member that was removed.

      1. Delete the peer secret:

         $ oc delete secret -n openshift-etcd etcd-peer-ip-10-0-131-183.ec2.internal

      2. Delete the serving secret:

         $ oc delete secret -n openshift-etcd etcd-serving-ip-10-0-131-183.ec2.internal

      3. Delete the metrics secret:

         $ oc delete secret -n openshift-etcd etcd-serving-metrics-ip-10-0-131-183.ec2.internal

3. Delete and recreate the master machine. After this machine is recreated, a new revision is forced and etcd scales up automatically.

   If you are running installer-provisioned infrastructure, or you used the Machine API to create your machines, follow these steps. Otherwise, you must create the new master using the same method that was used to originally create it.

   1. Obtain the machine for the unhealthy member.

      In a terminal that has access to the cluster as a cluster-admin user, run the following command:

      $ oc get machines -n openshift-machine-api -o wide

      Example output

      NAME                                        PHASE     TYPE        REGION      ZONE         AGE     NODE                           PROVIDERID                              STATE
      clustername-8qw5l-master-0                  Running   m4.xlarge   us-east-1   us-east-1a   3h37m   ip-10-0-131-183.ec2.internal   aws:///us-east-1a/i-0ec2782f8287dfb7e   stopped 1
      clustername-8qw5l-master-1                  Running   m4.xlarge   us-east-1   us-east-1b   3h37m   ip-10-0-154-204.ec2.internal   aws:///us-east-1b/i-096c349b700a19631   running
      clustername-8qw5l-master-2                  Running   m4.xlarge   us-east-1   us-east-1c   3h37m   ip-10-0-164-97.ec2.internal    aws:///us-east-1c/i-02626f1dba9ed5bba   running
      clustername-8qw5l-worker-us-east-1a-wbtgd   Running   m4.large    us-east-1   us-east-1a   3h28m   ip-10-0-129-226.ec2.internal   aws:///us-east-1a/i-010ef6279b4662ced   running
      clustername-8qw5l-worker-us-east-1b-lrdxb   Running   m4.large    us-east-1   us-east-1b   3h28m   ip-10-0-144-248.ec2.internal   aws:///us-east-1b/i-0cb45ac45a166173b   running
      clustername-8qw5l-worker-us-east-1c-pkg26   Running   m4.large    us-east-1   us-east-1c   3h28m   ip-10-0-170-181.ec2.internal   aws:///us-east-1c/i-06861c00007751b0a   running

      1

      This is the master machine for the unhealthy node, ip-10-0-131-183.ec2.internal.

   2. Save the machine configuration to a file on your file system:

      $ oc get machine clustername-8qw5l-master-0 \ 1
          -n openshift-machine-api \
          -o yaml \
          > new-master-machine.yaml

      1

      Specify the name of the master machine for the unhealthy node.

   3. Edit the new-master-machine.yaml file that was created in the previous step to assign a new name and remove unnecessary fields.

      1. Remove the entire status section:

         status:
           addresses:
           - address: 10.0.131.183
             type: InternalIP
           - address: ip-10-0-131-183.ec2.internal
             type: InternalDNS
           - address: ip-10-0-131-183.ec2.internal
             type: Hostname
           lastUpdated: "2020-04-20T17:44:29Z"
           nodeRef:
             kind: Node
             name: ip-10-0-131-183.ec2.internal
             uid: acca4411-af0d-4387-b73e-52b2484295ad
           phase: Running
           providerStatus:
             apiVersion: awsproviderconfig.openshift.io/v1beta1
             conditions:
             - lastProbeTime: "2020-04-20T16:53:50Z"
               lastTransitionTime: "2020-04-20T16:53:50Z"
               message: machine successfully created
               reason: MachineCreationSucceeded
               status: "True"
               type: MachineCreation
             instanceId: i-0fdb85790d76d0c3f
             instanceState: stopped
             kind: AWSMachineProviderStatus

      2. Change the metadata.name field to a new name.

         It is recommended to keep the same base name as the old machine and change the ending number to the next available number. In this example, clustername-8qw5l-master-0 is changed to clustername-8qw5l-master-3.

         For example:

         apiVersion: machine.openshift.io/v1beta1
         kind: Machine
         metadata:
           ...
           name: clustername-8qw5l-master-3
           ...

      3. Update the metadata.selfLink field to use the new machine name from the previous step.

         apiVersion: machine.openshift.io/v1beta1
         kind: Machine
         metadata:
           ...
           selfLink: /apis/machine.openshift.io/v1beta1/namespaces/openshift-machine-api/machines/clustername-8qw5l-master-3
           ...

      4. Remove the spec.providerID field:

           providerID: aws:///us-east-1a/i-0fdb85790d76d0c3f

      5. Remove the metadata.annotations and metadata.generation fields:

           annotations:
             machine.openshift.io/instance-state: running
           ...
           generation: 2

      6. Remove the metadata.resourceVersion and metadata.uid fields:

           resourceVersion: "13291"
           uid: a282eb70-40a2-4e89-8009-d05dd420d31a

   4. Delete the machine of the unhealthy member:

      $ oc delete machine -n openshift-machine-api clustername-8qw5l-master-0 1

      1

      Specify the name of the master machine for the unhealthy node.

   5. Verify that the machine was deleted:

      $ oc get machines -n openshift-machine-api -o wide

      Example output

      NAME                                        PHASE     TYPE        REGION      ZONE         AGE     NODE                           PROVIDERID                              STATE
      clustername-8qw5l-master-1                  Running   m4.xlarge   us-east-1   us-east-1b   3h37m   ip-10-0-154-204.ec2.internal   aws:///us-east-1b/i-096c349b700a19631   running
      clustername-8qw5l-master-2                  Running   m4.xlarge   us-east-1   us-east-1c   3h37m   ip-10-0-164-97.ec2.internal    aws:///us-east-1c/i-02626f1dba9ed5bba   running
      clustername-8qw5l-worker-us-east-1a-wbtgd   Running   m4.large    us-east-1   us-east-1a   3h28m   ip-10-0-129-226.ec2.internal   aws:///us-east-1a/i-010ef6279b4662ced   running
      clustername-8qw5l-worker-us-east-1b-lrdxb   Running   m4.large    us-east-1   us-east-1b   3h28m   ip-10-0-144-248.ec2.internal   aws:///us-east-1b/i-0cb45ac45a166173b   running
      clustername-8qw5l-worker-us-east-1c-pkg26   Running   m4.large    us-east-1   us-east-1c   3h28m   ip-10-0-170-181.ec2.internal   aws:///us-east-1c/i-06861c00007751b0a   running

   6. Create the new machine using the new-master-machine.yaml file:

      $ oc apply -f new-master-machine.yaml

   7. Verify that the new machine has been created:

      $ oc get machines -n openshift-machine-api -o wide

      Example output

      NAME                                        PHASE          TYPE        REGION      ZONE         AGE     NODE                           PROVIDERID                              STATE
      clustername-8qw5l-master-1                  Running        m4.xlarge   us-east-1   us-east-1b   3h37m   ip-10-0-154-204.ec2.internal   aws:///us-east-1b/i-096c349b700a19631   running
      clustername-8qw5l-master-2                  Running        m4.xlarge   us-east-1   us-east-1c   3h37m   ip-10-0-164-97.ec2.internal    aws:///us-east-1c/i-02626f1dba9ed5bba   running
      clustername-8qw5l-master-3                  Provisioning   m4.xlarge   us-east-1   us-east-1a   85s     ip-10-0-133-53.ec2.internal    aws:///us-east-1a/i-015b0888fe17bc2c8   running 1
      clustername-8qw5l-worker-us-east-1a-wbtgd   Running        m4.large    us-east-1   us-east-1a   3h28m   ip-10-0-129-226.ec2.internal   aws:///us-east-1a/i-010ef6279b4662ced   running
      clustername-8qw5l-worker-us-east-1b-lrdxb   Running        m4.large    us-east-1   us-east-1b   3h28m   ip-10-0-144-248.ec2.internal   aws:///us-east-1b/i-0cb45ac45a166173b   running
      clustername-8qw5l-worker-us-east-1c-pkg26   Running        m4.large    us-east-1   us-east-1c   3h28m   ip-10-0-170-181.ec2.internal   aws:///us-east-1c/i-06861c00007751b0a   running

      1

      The new machine, clustername-8qw5l-master-3 is being created and is ready once the phase changes from Provisioning to Running.

      It might take a few minutes for the new machine to be created. The etcd cluster Operator will automatically sync when the machine or node returns to a healthy state.

Verification

1. Verify that all etcd pods are running properly.

   In a terminal that has access to the cluster as a cluster-admin user, run the following command:

   $ oc get pods -n openshift-etcd | grep etcd

   Example output

   etcd-ip-10-0-133-53.ec2.internal                 3/3     Running     0          7m49s
   etcd-ip-10-0-164-97.ec2.internal                 3/3     Running     0          123m
   etcd-ip-10-0-154-204.ec2.internal                3/3     Running     0          124m

   If the output from the previous command only lists two pods, you can manually force an etcd redeployment. In a terminal that has access to the cluster as a cluster-admin user, run the following command:

   $ oc patch etcd cluster -p='{"spec": {"forceRedeploymentReason": "recovery-'"$( date --rfc-3339=ns )"'"}}' --type=merge 1

   1

   The forceRedeploymentReason value must be unique, which is why a timestamp is appended.

2. Verify that there are exactly three etcd members.

   1. Connect to the running etcd container, passing in the name of a pod that was not on the affected node:

      In a terminal that has access to the cluster as a cluster-admin user, run the following command:

      $ oc rsh -n openshift-etcd etcd-ip-10-0-154-204.ec2.internal

   2. View the member list:

      sh-4.2# etcdctl member list -w table

      Example output

      +------------------+---------+------------------------------+---------------------------+---------------------------+
      |        ID        | STATUS  |             NAME             |        PEER ADDRS         |       CLIENT ADDRS        |
      +------------------+---------+------------------------------+---------------------------+---------------------------+
      | 5eb0d6b8ca24730c | started |  ip-10-0-133-53.ec2.internal |  https://10.0.133.53:2380 |  https://10.0.133.53:2379 |
      | 757b6793e2408b6c | started |  ip-10-0-164-97.ec2.internal |  https://10.0.164.97:2380 |  https://10.0.164.97:2379 |
      | ca8c2990a0aa29d1 | started | ip-10-0-154-204.ec2.internal | https://10.0.154.204:2380 | https://10.0.154.204:2379 |
      +------------------+---------+------------------------------+---------------------------+---------------------------+

      If the output from the previous command lists more than three etcd members, you must carefully remove the unwanted member.

      警告

      Be sure to remove the correct etcd member; removing a good etcd member might lead to quorum loss.

Procedure

1. Stop the crashlooping etcd pod.

   1. Debug the node that is crashlooping.

      In a terminal that has access to the cluster as a cluster-admin user, run the following command:

      $ oc debug node/ip-10-0-131-183.ec2.internal 1

      1

      Replace this with the name of the unhealthy node.

   2. Change your root directory to the host:

      sh-4.2# chroot /host

   3. Move the existing etcd pod file out of the kubelet manifest directory:

      sh-4.2# mkdir /var/lib/etcd-backup

      sh-4.2# mv /etc/kubernetes/manifests/etcd-pod.yaml /var/lib/etcd-backup/

   4. Move the etcd data directory to a different location:

      sh-4.2# mv /var/lib/etcd/ /tmp

      You can now exit the node shell.

2. Remove the unhealthy member.

   1. Choose a pod that is not on the affected node.

      In a terminal that has access to the cluster as a cluster-admin user, run the following command:

      $ oc get pods -n openshift-etcd | grep etcd

      Example output

      etcd-ip-10-0-131-183.ec2.internal                2/3     Error       7          6h9m
      etcd-ip-10-0-164-97.ec2.internal                 3/3     Running     0          6h6m
      etcd-ip-10-0-154-204.ec2.internal                3/3     Running     0          6h6m

   2. Connect to the running etcd container, passing in the name of a pod that is not on the affected node.

      In a terminal that has access to the cluster as a cluster-admin user, run the following command:

      $ oc rsh -n openshift-etcd etcd-ip-10-0-154-204.ec2.internal

   3. View the member list:

      sh-4.2# etcdctl member list -w table

      Example output

      +------------------+---------+------------------------------+---------------------------+---------------------------+
      |        ID        | STATUS  |             NAME             |        PEER ADDRS         |       CLIENT ADDRS        |
      +------------------+---------+------------------------------+---------------------------+---------------------------+
      | 62bcf33650a7170a | started | ip-10-0-131-183.ec2.internal | https://10.0.131.183:2380 | https://10.0.131.183:2379 |
      | b78e2856655bc2eb | started |  ip-10-0-164-97.ec2.internal |  https://10.0.164.97:2380 |  https://10.0.164.97:2379 |
      | d022e10b498760d5 | started | ip-10-0-154-204.ec2.internal | https://10.0.154.204:2380 | https://10.0.154.204:2379 |
      +------------------+---------+------------------------------+---------------------------+---------------------------+

      Take note of the ID and the name of the unhealthy etcd member, because these values are needed later in the procedure.

   4. Remove the unhealthy etcd member by providing the ID to the etcdctl member remove command:

      sh-4.2# etcdctl member remove 62bcf33650a7170a

      Example output

      Member 62bcf33650a7170a removed from cluster ead669ce1fbfb346

   5. View the member list again and verify that the member was removed:

      sh-4.2# etcdctl member list -w table

      Example output

      +------------------+---------+------------------------------+---------------------------+---------------------------+
      |        ID        | STATUS  |             NAME             |        PEER ADDRS         |       CLIENT ADDRS        |
      +------------------+---------+------------------------------+---------------------------+---------------------------+
      | b78e2856655bc2eb | started |  ip-10-0-164-97.ec2.internal |  https://10.0.164.97:2380 |  https://10.0.164.97:2379 |
      | d022e10b498760d5 | started | ip-10-0-154-204.ec2.internal | https://10.0.154.204:2380 | https://10.0.154.204:2379 |
      +------------------+---------+------------------------------+---------------------------+---------------------------+

      You can now exit the node shell.

3. Remove the old secrets for the unhealthy etcd member that was removed.

   1. List the secrets for the unhealthy etcd member that was removed.

      $ oc get secrets -n openshift-etcd | grep ip-10-0-131-183.ec2.internal 1

      1

      Pass in the name of the unhealthy etcd member that you took note of earlier in this procedure.

      There is a peer, serving, and metrics secret as shown in the following output:

      Example output

      etcd-peer-ip-10-0-131-183.ec2.internal              kubernetes.io/tls                     2      47m
      etcd-serving-ip-10-0-131-183.ec2.internal           kubernetes.io/tls                     2      47m
      etcd-serving-metrics-ip-10-0-131-183.ec2.internal   kubernetes.io/tls                     2      47m

   2. Delete the secrets for the unhealthy etcd member that was removed.

      1. Delete the peer secret:

         $ oc delete secret -n openshift-etcd etcd-peer-ip-10-0-131-183.ec2.internal

      2. Delete the serving secret:

         $ oc delete secret -n openshift-etcd etcd-serving-ip-10-0-131-183.ec2.internal

      3. Delete the metrics secret:

         $ oc delete secret -n openshift-etcd etcd-serving-metrics-ip-10-0-131-183.ec2.internal

4. Force etcd redeployment.

   In a terminal that has access to the cluster as a cluster-admin user, run the following command:

   $ oc patch etcd cluster -p='{"spec": {"forceRedeploymentReason": "single-master-recovery-'"$( date --rfc-3339=ns )"'"}}' --type=merge 1

   1

   The forceRedeploymentReason value must be unique, which is why a timestamp is appended.

   When the etcd cluster Operator performs a redeployment, it ensures that all master nodes have a functioning etcd pod.