Setup different deploy keys for different GitHub repositories

We want to allow a foreign machine to read and write to a GitHub repository. We will use a GitHub "deploy" key to accomplish this. This process allows you to use different key-pairs for different GitHub repositoies in the same GitHub account.

Say you have two projects project1 and project2 in your GitHub account. You can set up the same deploy key for both projects or different keys for each.

1. We assume that the GitHub repository is called project9.

2. Create a new SSH key-pair. For the e-mail address you can put anything you want; it is just a label.

     ssh-keygen -t rsa -b 4096 -C "your_email@example.com" -f project9
   

3. The above comand created two files: project9 (containing the private part of of the key-pair) and project9.pub (containing the public part).

4. Move these two files into your usual .ssh directory where all your SSH options and other keyfiles are kept. For example:

     mv project9* $HOME/.ssh/
   

5. Add the public key (project9) as a deploy key in the GitHub repository project. Be sure to CHECK the "Allow write access" box.

6. Clone the GitHub repository:

    git clone https://github.com/githubuser/project9.git
   

7. Change directory into the cloned repository:

    cd project9
   

8. Configure this working directory to use the project9 SSH private key when pushing:

     git config core.sshCommand "ssh -i ~/.ssh/project9 -F /dev/null"
   

9. Change the URL from https to ssh:

    git remote set-url origin git@github.com:githubuser/project9.git
   

10. Now you can push.