Gitlab.com CI cannot logon to SSH server - ssh

Question

Most of the repositories of my private projects are hosted on a private repository on gitlab.com (the hosted solution, not a privately hosted gitlab server). The sites are hosted on a digitalocean VPS.
I want to use gitlab CI to have every commit on the develop branch automatically deployed on the test server. Since I already have a clone of the repository on this test server the easiest way to automatically deploy seems to have gitlab-ci connect to the ssh server, and trigger a git pull.
The gitlab-ci.yml I have now (ssh before_script copied from http://docs.gitlab.com/ce/ci/ssh_keys/README.html).
deploy to test:
environment: test
only:
- develop
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 || ( apt-get update -y && apt-get install openssh-client -y )'
# Run ssh-agent (inside the build environment)
- eval $(ssh-agent -s)
# add ssh key stored in SSH_PRIVATE_KEY variable to the agent store
- ssh-add <(echo "$SSH_PRIVATE_KEY")
# disable host key checking (NOTE: makes you susceptible to man-in-the-middle attacks)
# WARNING: use only in docker container, if you use it with shell you will overwrite your user's ssh config
- mkdir -p ~/.ssh
- echo -e "Host *\n\tStrictHostKeyChecking no\n\n" > ~/.ssh/config
script:
# Try and connect to the test server
- ssh [myname]#[mydomain.com] "cd /var/www/test.[projectname].com/ && git pull"
The result of a commit on develop in the gitlab pipelines:
$ ssh [myname]#[mydomain.com] "cd /var/www/test.[projectname].com/ && git pull"
Warning: Permanently added '[mydomain.com],[255.255.255.255]' (ECDSA) to the list of known hosts.
Permission denied, please try again.
Permission denied, please try again.
Permission denied (publickey,password).
ERROR: Build failed: exit code 1
I have the private key of my local user on my laptop added to the SSH_PRIVATE_KEY variable on gitlab. The private key should work since I can connect to the server from my laptop without providing a password.
Does anyone have this working, how can the gitlab.com worker connect to the ssh server?

Answer 1

AFAIK, you can't do this:
# add ssh key stored in SSH_PRIVATE_KEY variable to the agent store
- ssh-add <(echo "$SSH_PRIVATE_KEY")
The ssh-agent is not getting the key context, nor the FD. You should store the key in some temporary file and then add it to the agent (and potentially remove the file, if it is not needed anymore):
# add ssh key stored in SSH_PRIVATE_KEY variable to the agent store
- echo "$SSH_PRIVATE_KEY" > key
- chmod 600 key
- ssh-add key
- rm key