Adding ssh_private_key_file to ProxyCommand

This is trying to match what the roles/bastion-ssh-config is trying to do. When the setup is going through bastion, we want to ssh private key to be used on the bastion instance.

roles/kubespray-defaults/defaults/main.yaml

@@ -5,7 +5,7 @@ bootstrap_os: none
 
 # Use proxycommand if bastion host is in group all
 # This change obseletes editing ansible.cfg file depending on bastion existance
-ansible_ssh_common_args: "{% if 'bastion' in groups['all'] %} -o ProxyCommand='ssh -o UserKnownHostsFile=/dev/null -o StrictHostKeyChecking=no -W %h:%p {{ ansible_user }}@{{hostvars['bastion']['ansible_host']}} ' {% endif %}"
+ansible_ssh_common_args: "{% if 'bastion' in groups['all'] %} -o ProxyCommand='ssh -o UserKnownHostsFile=/dev/null -o StrictHostKeyChecking=no -W %h:%p {{ ansible_user }}@{{hostvars['bastion']['ansible_host']}} {% if ansible_ssh_private_key_file is defined %}-i {{ ansible_ssh_private_key_file }}{% endif %} ' {% endif %}"
 
 kube_api_anonymous_auth: false