Git Series: Multiple Credential Git Config

Why?

Have you ever in a position where you should push your repositories with another git account? When you try to register the account and try to clone the private repository from new account, and it got rejected because your device already been bound to your old personal account.

Also, when you solve the first question, are you wondering why, your commits are bound to your old account?

There are several possibilities why you need this:

You are a member of a company that build proprietary software, which need you to create a new github account using their email address domain
You have privacy concern regarding your “private” account and “working” account
You have multiple personas on internet

Glossary
Handling Credentials on Git Clone & Git Push
- HTTP Git Config
- SSH Git Config
  - Another Useful Usecases of SSH Key Config
Handling Credentials on Git Commit

Glossary

Hold on, usually glossary found as a footnote, why here though?

Because you need to know where to set it up

Directories:

Home Directory: <HOME_DIRECTORY>
- Windows: C:\Users\yourname\
- Linux/Mac: /home/yourname
SSH config directory: <SSH_CONFIG_DIRECTORY>
- <HOME_DIRECTORY>/.ssh

Files:

SSH Config File: <HOME_DIRECTORY>/.ssh/config
Main Git Config File: <HOME_DIRECTORY>/.gitconfig

Handling Credentials on Git Clone & Git Push

HTTP Git Config

⚠️ Caution, this method is a bit ancient, preferable to use SSH protocol, but I will cover it anyway

Main Settings:

Open your <HOME_DIRECTORY>/.gitconfig
Make sure useHttpPath was set to true in credential section. If there is no credential section yet, just create it:

[credential]
	useHttpPath = true

This will ensure that you won’t use same credential for same server, let’s say you have 2 github account on different repo, you will be prompted a password for each repository

Bonus:

In windows, there are several credential manager, but the one works best for me is manager-core. To set it up, open <HOME_DIRECTORY>/.gitconfig:

[credential "helperselector"]
	selected = manager-core

In linux, I haven’t tried it (literally), since I use SSH based credential now. But if you’re interested, here’s an article for you: https://kasunc.medium.com/git-credential-management-with-gnome-passwords-and-keys-seahorse-in-linux-e7b59b3b4d3d
In mac, will be automatically handled by git-credential-osxkeychain

SSH Git Config

Steps:

Open terminal/cmd, go to <SSH_CONFIG_DIRECTORY>
Generate new ssh key, change [email protected] with your first git account’s email: ssh-keygen -t ed25519 -C "[email protected]" -f firstgitusername

Notes:
- ed25519 can be changed to other algorithm
- this is optional if you have registered your ssh key beforehand, but make sure you still have the private key file
To be sure, now you should have file with name firstgitusername (private key), and firstgitusername.pub (public key)
Then add the key to your git remote provider: (this will use your firstgitusername.pub to set up)
- Provider guide:
  - github
  - gitlab or its enterprise self-hosted version
- TL;DR version:
  - open your firstgitusername.pub using any means, it can be cat tool, or any text editor
  - copy the content
  - go to your provider account setting
  - somewhere there should be SSH Keys menu
  - add key, they will prompt you to insert public key content there, paste the thing you copied before

Repeat the step 2, for your second account. Let’s say we now have secondgitusername (private key), and secondgitusername.pub (public key)
Save both key in <SSH_CONFIG_DIRECTORY>, at least the private key, but it’ll be better if also with the public key, for easier backup and migrating to another machine.

Notes:
- The location of the files actually can be anywhere, this guide is specifically made to make sure a beginner can follow.
- you can choose to not follow this guide but make sure you know where to find it.
Now you have these files in <SSH_CONFIG_DIRECTORY>:
- firstgitusername
- firstgitusername.pub
- secondgitusername
- secondgitusername.pub

Now open <HOME_DIRECTORY>/.ssh/config with any text editor. if not exist, create the file.
Write these config:

Host github.com
    HostName github.com
    IdentityFile ~/.ssh/firstgitusername
    IdentitiesOnly yes

Host firstgitusername
    HostName github.com
    IdentityFile ~/.ssh/firstgitusername
    IdentitiesOnly yes

Host secondgitusername
    HostName github.com
    IdentityFile ~/.ssh/secondgitusername
    IdentitiesOnly yes

Explanation and changes you can made:

HostName: your git remote provider url, for example: github.com, gitlab.com, yourcompanygitlabdomain.com
Host: name that you want to customize to access certain git repository. this will change how you interact with remote url
- When Host is the same with HostName, it is a default account when you try to just copy url from git provider and paste the command
- When Host is different, you will need to change the URL first, for example:
  - You copy your private repository clone url which is like this: [email protected]:someone/repo.git
    - Note: github.com is just a sample, it can be any HostName depends on where your git remote is
  - For example, it is accessible in your second account only, you will need to change it to git@secondgitusername:someone/repo.git before using it in git clone command / git remote add command
IdentityFile: where your private key located.
- if you follow my guide to save it in <SSH_CONFIG_DIRECTORY>, you can safely use ~/.ssh/ as the directory, it will work both in any OS.
- If you save it in custom directory, either you need to use full path, or you can use relative path from your <HOME_DIRECTORY>, depends on where you save your file

Now try to clone some of the private repository you have with custom host syntax explained in point 7. For example: git clone git@secondgitusername:someone/repo.git

Another Useful Usecases of SSH key config

Now you know that you can create custom Host to access your git repository using SSH.

Rather than only for personal benefit, this could lead to a new standard for multiple use cases:

Private project dependencies for proprietary software, if you don’t know how to create a private Package Repositories for your language (except gradle), or your language doesn’t support private package repository but support git dependency
- The idea:
  - Decide a unique name for “Host”
  - Ask all the contributor to setup SSH Git Config, using their account’s key, and specified “Host” + “HostName”
    - for example, on your secondgitusername, with Host “lalala” (must be same for everyone), and HostName “github.com”
- Example setup:
  - We will use Node.js dependencies as example (package.json)
  - You have prepare a package saved in git: [email protected]:secondgitusername/repo.git
  - Version 1 of the package is tagged in tag: v1.0.0
  - Package name is @astrojs/svelte
  - Your decided host is lalala
  - Open your project package.json and add the dependencies entry like this: "@astrojs/svelte": "git@lalala:secondgitusername/repo.git#tags/v5.4.0",
  - Now everyone who needs to open the project can safely install the dependencies
  - also CI/CD runner will be able to do the same, as long as the runner’s ssh config is also properly setup either using the pipeline/OS setting

Handling Credentials on Git Commit

Open your <HOME_DIRECTORY>/.gitconfig
Make sure the user part is setup properly:

Note:
- name: your visible name in git commit
- email: your main account git email. for me, it’s my personal account

[user]
	name = Your Name
	email = [email protected]

Create a directory for your second account, for this example I’ll use C:\Users\username\secondaccountproject
add this section in .gitconfig:

Note:
- all path should use slash, regardless of OS
- use full path, do not use abbreviation such as ~

[includeIf "gitdir/i:C:/Users/username/secondaccountproject/"]
	path = C:/Users/username/secondaccountproject/.gitconfig

Create and open .gitconfig file on your new directory (C:/Users/username/secondaccountproject/.gitconfig)
Fill it with:

Note:
- name: your visible name in git commit
- email: your second account git email.

[user]
	name = Your Name
	email = [email protected]

Create a new directory to test inside C:\Users\username\secondaccountproject, lets say, testrepository directory
Open the directory using terminal
Run command git config --get user.email. If success, it will show [email protected].

When a directory is not a git repository, git config will show “Main Git Config” value

Now, run git init in that directory, and check git config --get user.email again. It will show [email protected].

This means, your configuration is successful

Now, when you want to work with your second account, you should put your project in that specific directory (in this sample: C:\Users\username\secondaccountproject)

Note:

you can repeat this step and add setting to different directory for other accounts.
Also, with this information, now you could also add a bunch of different git config in a specific directory, not just name/email.