AWS環境で、Jenkins-slaveを追加する

環境

master
amazon linux (2017/04/01時点の最新)
java java-1.8.0-openjdk
Jenkins 2.52

slave
amazon linux (2017/04/01時点の最新)
java java-1.8.0-openjdk

JenkinsのSSHスレーブサーバを追加したところ以下のエラーが発生して
上手くslaveサーバを追加できなかったので、その対処方法。

[04/01/17 09:51:23] [SSH] Opening SSH connection to 172.31.xxx.xxx:22.
/var/lib/jenkins/.ssh/known_hosts [SSH] No Known Hosts file was found at /var/lib/jenkins/.ssh/known_hosts. Please ensure one is created at this path and that Jenkins can read it.
Key exchange was not finished, connection is closed.
java.io.IOException: There was a problem while connecting to 172.31.xxx.xxx:22
	at com.trilead.ssh2.Connection.connect(Connection.java:818)
	at com.trilead.ssh2.Connection.connect(Connection.java:687)
	at com.trilead.ssh2.Connection.connect(Connection.java:601)
	at hudson.plugins.sshslaves.SSHLauncher.openConnection(SSHLauncher.java:1265)
	at hudson.plugins.sshslaves.SSHLauncher$2.call(SSHLauncher.java:790)
	at hudson.plugins.sshslaves.SSHLauncher$2.call(SSHLauncher.java:785)
	at java.util.concurrent.FutureTask.run(FutureTask.java:262)
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
	at java.lang.Thread.run(Thread.java:745)
Caused by: java.io.IOException: Key exchange was not finished, connection is closed.
	at com.trilead.ssh2.transport.KexManager.getOrWaitForConnectionInfo(KexManager.java:93)
	at com.trilead.ssh2.transport.TransportManager.getConnectionInfo(TransportManager.java:230)
	at com.trilead.ssh2.Connection.connect(Connection.java:770)
	... 9 more
Caused by: java.io.IOException: The server hostkey was not accepted by the verifier callback
	at com.trilead.ssh2.transport.KexManager.handleMessage(KexManager.java:535)
	at com.trilead.ssh2.transport.TransportManager.receiveLoop(TransportManager.java:777)
	at com.trilead.ssh2.transport.TransportManager$1.run(TransportManager.java:489)
	... 1 more
[04/01/17 09:51:23] Launch failed - cleaning up connection
[04/01/17 09:51:23] [SSH] Connection closed.

#対処方法を先に記載します。
管理者でログインし、
[Jenkinsの管理]-[ノードの管理]へ移動し、今回エラーが出ているノードを選択します。

Host Key Verification Strategyの設定値を変更する。
「Known hosts file Verification strategy」
　　　　　　　　　　↓
「Manually trusted key Verification Strategy」

参考ページ

#その他
Jenkins slaveの追加を書こうかと思ったのですが、他の方々が書かれているので今回は割愛します。

#追伸
SSH Slaves pluginのアップデートした場合以下のメッセージが出るようです。

SSH Host Key Verifiers are not configured for all SSH slaves on this Jenkins instance. This could leave these slaves open to man-in-the-middle attacks. Update your slave configuration to resolve this.

その場合も、「Manually trusted key Verification Strategy」に変更することで、エラーがなくなります。