title: Create/associate ssh keypair to an ec2 instance with the CDK
body: <p>I'm using the new Cloud Development Toolkit (CDK) to build an infrastructure on AWS using Java language.</p>
  
  <p>I'm using a Bastion Host on a public subnet to communicate with an RDS instance on a private subnet, so I reach the database (on the private subnet) externally via an ssh tunnelling on the Bastion Host.</p>
  
  <p>I've created the BastionHost in this way:</p>
  
  <pre><code>BastionHostLinux
              .Builder
              .create(scope, bastionId)
              .vpc(vpc)
              .instanceType(InstanceType.of(InstanceClass.BURSTABLE2, InstanceSize.SMALL))
              .subnetSelection(subnetSelection)
              .instanceName(bastionName)
              .build();
  </code></pre>
  
  <p>I don't find any method to create or associate ssh key pair to the instance, so when I try to connect, aws tell me that I don't have any ssh key pair associated with the ec2 instance.</p>
  
  <p>My question is: How can I associate an already existent keypair with an ec2 instance using the CDK? Or, (it would be better) how can I create a fresh key pair using the CDK?</p>