Overview

Enable the use of multiple ssh-keys (for multiple accounts) in a non intrusive manner. It relies on / uses the following concepts:

• Using insteadOf in .gitconfig (Ref)
• Using an ssh config file (Ref
• 1Password 8 (Ref) (ssh-agent can be used instead)
• Specify exact key in ssh-agent (1password) to be used (Ref)
• General guidance on using multiple ssh keys (Ref)

How this guide is different

The general suggestions found via searching google requires the developer to change the “hostname” when they do a clone. This is a manual step that takes away the ease of clicking on the Github code/clone “copy” button.

With the setup as described here, the normal flow remains unchanged.

Example

Assume we want to configure 2 ssh keys for 2 different github accounts.

• Github account 1 (acc1) with ssh key acc1-ssh
• Github account 2 (acc2) with ssh key acc2-ssh

Steps

Setup SSH keys

Setup your SSH keys in github and ssh-agent (1password) as you’d normally do

Make public keys available

• Store acc1-ssh.pub in $HOME/.ssh/acc1-ssh.pub
• Store acc2-ssh.pub in $HOME/.ssh/acc2-ssh.pub

Update .ssh/config

Add the following to your $HOME/.ssh/config

Host acc1-github.com
    Hostname github.com
    IdentityFile ~/.ssh/acc1-ssh.pub

Host acc2-github.com
    Hostname github.com
    IdentityFile ~/.ssh/acc2-ssh.pub

This will cause the ssh client to use different ssh private keys (via ssh-agent) for the different domains. Setting the IdentityFile to the public key, tells ssh-agent which private key to use.

This is where the normal guidance for using multiple keys end. However, this requires the developer to change the url when cloning. I.e. instead of

git clone git@github.com:acc1/repo

the developer has to change the url and clone with the new url

git clone git@acc1-github.com:acc1/repo

Update $HOME/.gitconfig

Add the following to your $HOME/.gitconfig

[url "git@acc1-github.com:acc1"]
  insteadOf = git@github.com:acc1

[url "git@acc2-github.com:acc1"]
  insteadOf = git@github.com:acc2

This tells the git client to use git@acc1-github.com:acc1 instead of git@github.com:acc1, which in turn tells the ssh client to use the key associated with acc1-github.com.

The end result is that the developer can clone via

git clone git@github.com:acc1/repo

and the git remote will be setup as

origin git@acc1-github.com:acc1/repo.git