Replacing an unhealthy etcd member - Control plane backup and restore | Backup and restore

Prerequisites
Identifying an unhealthy etcd member
Determining the state of the unhealthy etcd member
Replacing the unhealthy etcd member
- Replacing an unhealthy etcd member whose machine is not running or whose node is not ready
- Replacing an unhealthy etcd member whose etcd pod is crashlooping

This document describes the process to replace a single unhealthy etcd member.

This process depends on whether the etcd member is unhealthy because the machine is not running or the node is not ready, or whether it is unhealthy because the etcd pod is crashlooping.

If you have lost the majority of your control plane hosts (also known as the master hosts), leading to etcd quorum loss, then you must follow the disaster recovery procedure to restore to a previous cluster state instead of this procedure.

If the control plane certificates are not valid on the member being replaced, then you must follow the procedure to recover from expired control plane certificates instead of this procedure.

If a control plane node is lost and a new one is created, the etcd cluster Operator handles generating the new TLS certificates and adding the node as an etcd member.

Prerequisites

Take an etcd backup prior to replacing an unhealthy etcd member.

Identifying an unhealthy etcd member

You can identify if your cluster has an unhealthy etcd member.

Prerequisites

Access to the cluster as a user with the cluster-admin role.

Procedure

Check the status of the EtcdMembersAvailable status condition using the following command:

$ oc get etcd -o=jsonpath='{range .items[0].status.conditions[?(@.type=="EtcdMembersAvailable")]}{.message}{"\n"}'

Review the output:
```
2 of 3 members are available, ip-10-0-131-183.ec2.internal is unhealthy
```
This example output shows that the ip-10-0-131-183.ec2.internal etcd member is unhealthy.

Determining the state of the unhealthy etcd member

The steps to replace an unhealthy etcd member depend on which of the following states your etcd member is in:

The machine is not running or the node is not ready
The etcd pod is crashlooping

This procedure determines which state your etcd member is in. This enables you to know which procedure to follow to replace the unhealthy etcd member.

If you are aware that the machine is not running or the node is not ready, but you expect it to return to a healthy state soon, then you do not need to perform a procedure to replace the etcd member. The etcd cluster Operator will automatically sync when the machine or node returns to a healthy state.

Prerequisites

You have access to the cluster as a user with the cluster-admin role.
You have identified an unhealthy etcd member.

Procedure

Determine if the machine is not running:
```
$ oc get machines -A -ojsonpath='{range .items[*]}{@.status.nodeRef.name}{"\t"}{@.status.providerStatus.instanceState}{"\n"}' | grep -v running
```
Example output
```
ip-10-0-131-183.ec2.internal  stopped (1)
```
1 This output lists the node and the status of the node’s machine. If the status is anything other than running, then the machine is not running.

If the machine is not running, then follow the Replacing an unhealthy etcd member whose machine is not running or whose node is not ready procedure.
Determine if the node is not ready.

If either of the following scenarios are true, then the node is not ready.
- If the machine is running, then check whether the node is unreachable:
  $ oc get nodes -o jsonpath='{range .items[*]}{"\n"}{.metadata.name}{"\t"}{range .spec.taints[*]}{.key}{" "}' | grep unreachable
  Example output
  ip-10-0-131-183.ec2.internal node-role.kubernetes.io/master node.kubernetes.io/unreachable node.kubernetes.io/unreachable (1)
  1 If the node is listed with an unreachable taint, then the node is not ready.
- If the node is still reachable, then check whether the node is listed as NotReady:
  $ oc get nodes -l node-role.kubernetes.io/master | grep "NotReady"
  Example output
  ip-10-0-131-183.ec2.internal NotReady master 122m v1.20.0 (1)
  1 If the node is listed as NotReady, then the node is not ready.
If the node is not ready, then follow the Replacing an unhealthy etcd member whose machine is not running or whose node is not ready procedure.

Determine if the etcd pod is crashlooping.

If the machine is running and the node is ready, then check whether the etcd pod is crashlooping.

Verify that all control plane nodes (also known as the master nodes) are listed as Ready:

$ oc get nodes -l node-role.kubernetes.io/master

Example output

NAME                           STATUS   ROLES    AGE     VERSION
ip-10-0-131-183.ec2.internal   Ready    master   6h13m   v1.20.0
ip-10-0-164-97.ec2.internal    Ready    master   6h13m   v1.20.0
ip-10-0-154-204.ec2.internal   Ready    master   6h13m   v1.20.0

Check whether the status of an etcd pod is either Error or CrashloopBackoff:

$ oc get pods -n openshift-etcd | grep -v etcd-quorum-guard | grep etcd

Example output

etcd-ip-10-0-131-183.ec2.internal                2/3     Error       7          6h9m (1)
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

1	Since this status of this pod is `Error`, then the etcd pod is crashlooping.

If the etcd pod is crashlooping, then follow the Replacing an unhealthy etcd member whose etcd pod is crashlooping procedure.

Replacing the unhealthy etcd member

Depending on the state of your unhealthy etcd member, use one of the following procedures:

Replacing an unhealthy etcd member whose machine is not running or whose node is not ready

This procedure details the steps to replace an etcd member that is unhealthy either because the machine is not running or because the node is not ready.

Prerequisites

You have identified the unhealthy etcd member.
You have verified that either the machine is not running or the node is not ready.
You have access to the cluster as a user with the cluster-admin role.
You have taken an etcd backup.

It is important to take an etcd backup before performing this procedure so that your cluster can be restored if you encounter any issues.

Procedure

Remove the unhealthy member.

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 -v etcd-quorum-guard | 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

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
```

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. The $ etcdctl endpoint health command will list the removed member until the procedure of replacement is finished and a new member is added.

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 ead669ce1fbfb346

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.

After you remove the member, the cluster might be unreachable for a short time while the remaining etcd instances reboot.

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

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

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

Delete the peer secret:

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

Delete the serving secret:

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

Delete the metrics secret:

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

Delete and recreate the control plane machine (also known as 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.

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 control plane machine for the unhealthy node, `ip-10-0-131-183.ec2.internal`.

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 control plane machine for the unhealthy node.

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

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

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
  ...
```

Remove the spec.providerID field:

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

Remove the metadata.annotations and metadata.generation fields:

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

Remove the metadata.resourceVersion and metadata.uid fields:

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

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 control plane machine for the unhealthy node.

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

Create the new machine using the new-master-machine.yaml file:
```
$ oc apply -f new-master-machine.yaml
```

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

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 -v etcd-quorum-guard | 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.

Verify that there are exactly three etcd members.

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
```

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.

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

Replacing an unhealthy etcd member whose etcd pod is crashlooping

This procedure details the steps to replace an etcd member that is unhealthy because the etcd pod is crashlooping.

Prerequisites

You have identified the unhealthy etcd member.
You have verified that the etcd pod is crashlooping.
You have access to the cluster as a user with the cluster-admin role.
You have taken an etcd backup.

It is important to take an etcd backup before performing this procedure so that your cluster can be restored if you encounter any issues.

Procedure

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.

Remove the unhealthy member.

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 -v etcd-quorum-guard | 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

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
```

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.

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

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.

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

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

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

Delete the peer secret:

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

Delete the serving secret:

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

Delete the metrics secret:

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

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 control plane nodes (also known as the master nodes) have a functioning etcd pod.

Verification

Verify that the new member is available and healthy.

Connect to the running etcd container again.

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
```

Verify that all members are healthy:

sh-4.2# etcdctl endpoint health --cluster

Example output

https://10.0.131.183:2379 is healthy: successfully committed proposal: took = 16.671434ms
https://10.0.154.204:2379 is healthy: successfully committed proposal: took = 16.698331ms
https://10.0.164.97:2379 is healthy: successfully committed proposal: took = 16.621645ms