[git] How to use a repo-specific ssh key

The problem

Once you have multiple accounts in GitLab you can’t use the same ssh key, so you have to generate a new ssh keypair and configure a repository to use the new key from a different location.

Steps

• Generate a new key

ssh-keygen -t rsa -f ./.ssh/git-lab-key

• Clone a repo with the new key

git -c core.sshCommand="ssh -i ~/{YOUR_PROJECT}/.ssh/git-lab-key" clone git@gitlab.com:<user>/<repo>.git

• Configure an existing repo to use the new key

git config core.sshCommand 'ssh -i ~/{YOUR_PROJECT}/.ssh/git-lab-key'