title: ansible ssh prompt known_hosts issue
body: <p>I'm running Ansible playbook and it works fine on one machine. </p>
  
  <p>On a new machine when I try for the first time, I get the following error.</p>
  
  <pre><code>17:04:34 PLAY [appservers] ************************************************************* 
  17:04:34 
  17:04:34 GATHERING FACTS *************************************************************** 
  17:04:34 fatal: [server02.cit.product-ref.dev] =&gt; {'msg': "FAILED: (22, 'Invalid argument')", 'failed': True}
  17:04:34 fatal: [server01.cit.product-ref.dev] =&gt; {'msg': "FAILED: (22, 'Invalid argument')", 'failed': True}
  17:04:34 
  17:04:34 TASK: [common | remove old ansible-tmp-*] ************************************* 
  17:04:34 FATAL: no hosts matched or all hosts have already failed -- aborting
  17:04:34 
  17:04:34 
  17:04:34 PLAY RECAP ******************************************************************** 
  17:04:34            to retry, use: --limit @/var/lib/jenkins/site.retry
  17:04:34 
  17:04:34 server01.cit.product-ref.dev      : ok=0    changed=0    unreachable=1    failed=0   
  17:04:34 server02.cit.product-ref.dev      : ok=0    changed=0    unreachable=1    failed=0   
  17:04:34 
  17:04:34 Build step 'Execute shell' marked build as failure
  17:04:34 Finished: FAILURE
  </code></pre>
  
  <p>This error can be resolved, if I first go to the source machine (from where I'm running the ansible playbook) and manually ssh to the target machine (as the given user) and enter "yes" for known_hosts file entry.</p>
  
  <p>Now, if I run the same ansible playbook second time, it works without an error.</p>
  
  <p>Therefore, how can I suppress the prompt what SSH gives while making ssh known_hosts entry for the first time for a given user (~/.ssh folder, file known_hosts)?</p>
  
  <p>I found I can do this if I use the following config entries in <strong>~/.ssh/config</strong> file.</p>
  
  <p>~/.ssh/config</p>
  
  <pre><code># For vapp virtual machines
  Host *
    StrictHostKeyChecking no
    UserKnownHostsFile=/dev/null
    User kobaloki
    LogLevel ERROR
  </code></pre>
  
  <p>i.e. if I place the above code in the user's ~/.ssh/config file of a remote machine and try Ansible playbook for the first time, I won't be prompted for entring "yes" and playbook will run successfully (without requiring the user to manually create a known_hosts file entry from the source machine to the target/remote machine).</p>
  
  <p>My questions:
  1. What security issues I should take care if I go ~/.ssh/config way
  2. How can I pass the settings (what's there in the config file) as parameters/options to ansible at command line so that it will run first time on a new machine (without prompting / depending upon the known_hosts file entry on the source machine for the target machine?</p>