gitlab-ci SSH key invalid format : <p>I would like run deploy script with gitlab-ci, but step ssh-add <code>$SSH_PRIVATE_KEY</code> return an error :</p>

<pre><code>echo "$SSH_PRIVATE_KEY" | ssh-add -
Error loading key "(stdin)": invalid format
</code></pre>

<p>You can see my <code>.gitlab-ci.yml</code> :</p>

<pre><code>deploy:
  image: node:9.11.1-alpine
  stage: deploy
  before_script:
    # Install ssh-agent if not already installed, it is required by Docker.
    # (change apt-get to yum if you use a CentOS-based image)
    - 'which ssh-agent || ( apk add --update openssh )'

    # Add bash
    - apk add --update bash

    # Add git
    - apk add --update git

    # Run ssh-agent (inside the build environment)
    - eval $(ssh-agent -s)

    # Add the SSH key stored in SSH_PRIVATE_KEY variable to the agent store
    - echo "$SSH_PRIVATE_KEY"
    - echo "$SSH_PRIVATE_KEY" | ssh-add -

    # For Docker builds disable host key checking. Be aware that by adding that
    # you are suspectible to man-in-the-middle attacks.
    # WARNING: Use this only with the Docker executor, if you use it with shell
    # you will overwrite your user's SSH config.
    - mkdir -p ~/.ssh
    - '[[ -f /.dockerenv ]] &amp;&amp; echo -e "Host *\n\tStrictHostKeyChecking no\n\n" &gt; ~/.ssh/config'
    # In order to properly check the server's host key, assuming you created the
    # SSH_SERVER_HOSTKEYS variable previously, uncomment the following two lines
    # instead.
    # - mkdir -p ~/.ssh
    # - '[[ -f /.dockerenv ]] &amp;&amp; echo "$SSH_SERVER_HOSTKEYS" &gt; ~/.ssh/known_hosts'
  script:
    - npm i -g pm2
    - pm2 deploy ecosystem.config.js production
  # only:
  # - master
</code></pre>

<p>On my project setting, i've been add SSH_PRIVATE_KEY variable, with the id_rsa from my production server <code>cat ~/.ssh/id_rsa.pub</code>.</p>

<p>Anyone can help me ?</p>
