Use puppet to generate ED25519 keys (for older systems or systems that didn't get them generated automatically)

ed25519-puppet-example.pp

if ($::operatingsystem == 'Ubuntu') {
  package { 'openssh-server' :
    ensure  => latest,
  }

  service  { 'ssh':
    ensure  => 'running',
    enable  => true,
    require => Package['openssh-server'],
  }

  $ssh_config_source = $::lsbdistcodename ? {
    'precise' => 'puppet:///modules/standard_packages/ssh/sshd_config.precise',
    default   => 'puppet:///modules/standard_packages/ssh/sshd_config',
  }

  file { 'sshdconfig':
    name    => '/etc/ssh/sshd_config',
    owner   => root,
    group   => root,
    mode    => '0644',
    source  => $ssh_config_source,
    require => Package['openssh-server'],
    notify  => Service['ssh'],
  }
  
  # Run ssh-keygen (ONLY if ed25519 key doesn't exist and we aren't on precise)
    unless ($::lsbdistcodename == 'precise') {
      exec { 'ED25519 ssh-keygen':
        command => "ssh-keygen -q -f /etc/ssh/ssh_host_ed25519_key -N '' -t ed25519",
        cwd     => '/etc/ssh',
        user    => 'root',
        creates => '/etc/ssh/ssh_host_ed25519_key',
        path    => ['/usr/bin', '/usr/sbin/', '/usr/local/sbin'],
        require => Package['openssh-server'],
        notify  => Service['ssh'],
      }
    }
  }