[fedora-atomic][k8s]Disable ssh password authentication

Regarding passwords, they could be guessed if there is no
faild-to-ban-like solution. So it'd better to disable it
for security reasons.

Task: 36300
Story: 2006413

Change-Id: Ie7534c12612750d9aafd4feae5193b34997b22ff

magnum/drivers/common/templates/kubernetes/fragments/start-container-agent.sh

@@ -43,6 +43,9 @@ Host localhost
 EOF
 
 sed -i '/^PermitRootLogin/ s/ .*/ without-password/' /etc/ssh/sshd_config
+# Security enhancement: Disable password authentication
+sed -i '/^PasswordAuthentication yes/ s/ yes/ no/' /etc/ssh/sshd_config
+
 systemctl restart sshd
 
 

releasenotes/notes/disable-ssh-password-authn-f2baf619710e52aa.yaml

@@ -0,0 +1,6 @@
+---
+security:
+  - |
+    Regarding passwords, they could be guessed if there is no
+    faild-to-ban-like solution. So it'd better to disable it for security
+    reasons. It's only effected for fedora atomic images.