git-ssh-shim

When using SSH to access git repositories, especially via GitHub, clients will sometimes require multiple SSH keys:

• Users may have multiple GitHub accounts, each with different keys, for different GitHub organizations; this scenario is particularly common among contractors and consultants who work with multiple GitHub organizations at once.

• Automated processes may use GitHub deploy keys -- which must be unique per repository -- and may wish to use the same SSH agent session to access multiple repositories.

Unfortunately, using multiple SSH keys with git (and GitHub) is not straightforward; it's quite easy to use a key that is recognized by the provider but not authorized for a specific repository, causing the git operation to fail and bypassing the client's normal key negotiation process.

A common solution is to write a shim program that handles key negotiation; this repository provides such a program.

Usage

1. Download the git-ssh-shim shell script.

   This guide will assume installation to the working directory.

2. Configure your environment to use this script for git ssh operations.

   If you are using deploy keys, simply set GIT_SSH_COMMAND to the shim:

   export GIT_SSH_COMMAND="$(pwd)/git-ssh-shim"

   If you are using user keys, include your GitHub username in the command:

   export GIT_SSH_COMMAND="$(pwd)/git-ssh-shim <github-username>"

3. Use ssh-agent (e.g. via ssh-add) to add keys you want to use.