Assign the user www-data an SSH key and add it to the remote repo

In the GIT Info Report, for public repos, you get warned if your local repo is behind, compared with the remote. To have the same information also for private repos, you should create an SSH key for the user www-data and add that key to your user profile on the remote repo.

Steps

• Check first what user is being used to run the CLI commands integrated into the module. In most cases, the user is www-data. We presume that in the rest of the instructions below. Substitute if necessary.
• In the terminal:
  • Create a new hidden directory:sudo mkdir /var/www/.ssh
  • Change folder permission: sudo chown -R www-data /var/www/.ssh
  • Create the ssh key as user www-data: sudo -u www-data ssh-keygen -t rsa
• Open the generated key file (/var/www/.ssh/id_rsa.pub) with a text editor and copy-paste the content to your user profile SSH Keys on the remote repo. On GitLab, when logged in, this is found at https://gitlab.com/profile/keys/.
• Then in the terminal from a Git repo, use sudo -u www-data git ls-remote to provoke the first connection to the remote repo as user www-data manually. It will say The authenticity of host X can't be established. Confirm you would like to add it to the list of known hosts. All points above are a one-time operation, per machine, per repository service provider. Once set correctly, it does not need to be repeated, not even for another project.
• Refresh the Status Report and check if after the remote repo address you now see either No pull needed or Your branch is behind. If so, it works as expected.

More info

• Gitlab webhooks not working due to shell script permission - Stack Overflow
• Making www-data push to local git repo - Stack Overflow