Failure to connect through ssh

Installation fails due to a SSH connection issue.

Symptoms

The following error message is displayed, and the installation fails.

fatal: [x.x.x.x] => Failed to connect to the host via ssh'

Passwordless SSH is not set up from boot to other nodes in the cluster.

For more information about setting up passwordless SSH, see Sharing SSH keys among cluster nodes.
Ensure that passwordless SSH is configured from boot node to all other nodes in the cluster. If a single node is used for both boot and master, you still must configure passwordless SSH on that node. Run the following commands to verify that passwordless SSH is configured in the cluster:
```
ssh -vvv -i cluster/ssh_key root@x.x.x.x
```