Working with multiple GPG keys across multiple git identities

Introduction

Its common to have multiple Git identities when working across different projects which can be difficult to manage but for the majority of us we usually have two git identities for signing commits: one for work use and one for personal use. This tutorial explains how to switch git identities automatically based on what directory your in.

Prerequisites

• Two GPG keys generated for two different emails. Refer to the Git Documentation on GPG
  
  

Configuring multiple git identities

The main Git configuration file is .gitconfig which can be found in the $HOME directory and is specfic to each user. Create two new git configuration files for work and personal use, see below.

-rw-r--r--  1 John John  234 May  8 15:52  .gitconfig
-rw-r--r--  1 John John   95 Sep 20 15:02  .gitconfig-local
-rw-r--r--  1 John John  137 Sep 20 15:02  .gitconfig-work

By default we are going to configure git to use our personal git identity for everything unless we are in a specific directory. Open up .gitconfig-local with a text editor and insert the contents based on your personal git identity:

emmet@homepc:~$ cat .gitconfig-local 
[user]
  name = John Doe
  email = johndoe@hotmail.co.uk
  signingkey = OEE3389VBDJH4531

Note: You can find the key ID for your GPG secret key via gpg --list-secret-keys --keyid-format LONG which is then sec rsa3072/OEE3389VBDJH4531

Save and Exit. Repeat the same for .gitconfig-work replacing name, email and signingkey ID with your git identity for work.

emmet@homepc:~$ cat .gitconfig-work 
[user]
  name = John Doe
  email = johndoe@company.net
  signingkey = BM2095449YAW90L1

Save and Exit. Create a new folder in Documents directory called work-projects which will be used for work related projects. Open the main git configuration file: .gitconfig and append the following to the file:

# default case
[include]
        path = ~/.gitconfig-local

[includeIf "gitdir:~/Documents/work-projects/**/.git"]
        path = ~/.gitconfig-work

The includeIf condition allows us to automatically switch git identities when inside the work-projects directory to .gitconfig-work.

Test automated switching

Git should now automatically detect the git identity based on the directory you are in. Run the following commands in your home directory:

emmet@homepc:~$ pwd
/home/john
emmet@homepc:~$ git config user.email 
johndoe@hotmail.co.uk
emmet@homepc:~$ git config user.signingKey 
OEE3389VBDJH4531

Git detects our configuration based on .gitconfig-local. Navigate into Documents/work-projects, clone any git project into work-projects directory, cd into it and then run the following commands again:

emmet@homepc:~/Documents/work-projects/tictactoe$ git config user.email 
johndoe@company.net
emmet@homepc:~/Documents/work-projects/tictactoe$ git config user.signingKey 
BM2095449YAW90L1

You can see Git automatically switching identities based on directories allowing us to manage multiple GPG keys when signing commits.