title: Dockerfile: skip passphrase for private key
body: <p>I'm using private keys for downloading my repository from Github in my Docker file. I have something like this:    </p>
  
  <pre><code>RUN mkdir -p /root/.ssh &amp;&amp; echo "$MY_PRIVATE_KEY" &gt;/root/.ssh/id_rsa &amp;&amp;    chmod 0600 /root/.ssh/id_rsa &amp;&amp;    ssh-keyscan github.com &gt;&gt; /root/.ssh/known_hosts &amp;&amp;    cat /root/.ssh/known_hosts &amp;&amp;    ssh -vvv git@github.com &amp;&amp;    pip install git+ssh://git@github.com/my_project.git@v1.0.0 &amp;&amp;    rm /root/.ssh/id_rsa
  </code></pre>
  
  <p>Where <code>MY_PRIVATE_KEY</code> is an argument. I'm not able to re-create this key.
  My issue is that during connection process I'm getting the following error:
  <code>key_load_private_type: incorrect passphrase supplied to decrypt private key</code></p>
  
  <p>Is it possible to skip passphrase somehow?</p>