title: GitLab CI failing with SSH error loading key invalid format
body: <p>I am starting to get into GitLab CI for my company. We have a PrestaShop, and I want automatic deployment to the web server after a Git push.</p>
  <p>Unit testing will come later. At the moment I just need it to deal with putting a copy of the &quot;/app&quot; folder in the web root of the web server.</p>
  <p>So this is what I have got...</p>
  <pre><code>before_script:
    - apt-get update -qq
    - apt-get install -qq git
    - 'which ssh-agent || ( apt-get install -qq openssh-client )'
    - eval $(ssh-agent -s)
    - ssh-add &lt;(echo &quot;$SSH_PRIVATE_KEY&quot;)
    - mkdir -p ~/.ssh
    - '[[ -f /.dockerenv ]] &amp;&amp; echo -e &quot;Host *\n\tStrictHostKeyChecking no\n\n&quot; &gt; ~/.ssh/config'
  
  
  deploy_test:
    type: deploy
    environment:
      name: test
      url: [test server domain]
    script:
      - ssh [user]@[server] -p [port] &quot;cd [repo folder] &amp;&amp; git checkout master &amp;&amp; git pull origin master &amp;&amp; exit&quot;
      - ssh [user]@[server] -p [port] &quot;rsync -rzvh [repo /app folder] [web server root path]&quot;
    only:
      - master
  </code></pre>
  <p>Recently, gitlab-runner has started failing with the error <code>Error loading key &quot;/dev/fd/63&quot;: invalid format</code>.</p>
  <p>Can you help me to solve that error?</p>
  <p>FYI, I have my personal private key set as $SSH_PRIVATE_KEY environment var in GitLab - the public on the web server of course. SSH is enabled on the web server which has WHM and cPanel. And I pre-checked out a copy of master via cPanel on the web server into the [repo folder].</p>