title: "Host key verification failed" on Gitlab_ci although ssh_key is present
body: <p>"Host key verification failed." <strong>on Gitlab_ci</strong> when running "ssh name@server"</p>
  
  <p>Here's a part of my gitlab_ci which is supposed to login to my server and run scripts from the repo:</p>
  
  <pre><code>script:
    - which ssh-agent || ( apt-get update -y &amp;&amp; apt-get install openssh-client -y )
    - eval $(ssh-agent -s)
    - ssh-add &lt;(echo -e "$SSH_PRIVATE_KEY")
  
  
    - echo "debug"
    - echo "$SSH_PRIVATE_KEY" # all is ok here, it'll be printed
    - echo "debug"
  
  
    # - here comes an error
    - (cat ./script/script1.sh) | ssh -t -t $SSH_USERNAME@$SSH_HOST
  </code></pre>
  
  <p>And the errror:</p>
  
  <pre><code>  Host key verification failed.
    ERROR: Job failed: exit code 1
  </code></pre>
  
  <p>Why the error? The variables are set. </p>
  
  <p><strong>The private key does work when I'm doing the same thing manually from my local computer and Gitlab.</strong></p>