vinayakg/staying-sane-using-multiple-git-accounts.md

## staying-sane-using-multiple-git-accounts.md

      
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              staying-sane-using-multiple-git-accounts.md
            
          
    The other day, I wanted to work with many git accounts on my laptop and I felt it was not easy and required many steps. I had to understood how things work actually when you use git via ssh and the role of ssh-agent. Also had to refer many articles and connect dots from them to be able to make it work for me. I felt I should document these steps so it can help other folks use this and save time and possible pain :-)
If you don't have the need to use many git accounts - am sure there will be learnings for you on how things actually work. So stay with me and keep reading
In case you have an existing git setup and looking to to start fresh, head to Troubleshoot section
Setting Up

Generate SSH keys

Check your current SSH keys (back if you need them before deleting or leave them). They are all located at ~/.ssh/. View them using ls -al ~/.ssh/
Generate new SSH keys using below commands
ssh-keygen -t rsa -C "vg@work.com" -f "id_work_user"
Set the passphrase, so the keys are secure even if you loose device. Also let's use RSA and avoid using DSA based algorithms (blog post coming soon on that). There are 2 files generated id_work_user and id_work_user.pub at the location ~/.ssh.
Let's dissect the above command.
-t option to specify the encryption algorithm, default is DSA. I will write more about how DSA can be brute forced even with password enabled ssh keys
-C comment that will help us associate the key with its purpose, we will see the command later
-f file name to use for saving
Run the above command for the other git accounts too
ssh-keygen -t rsa -C "vinayakg@personal.com" -f "id_my_user"
All the generated keys will be at ~/.ssh and we have 2 private keys (no extn) and 2 public keys (.pub)
Let your provider know these keys

This will help us setup the auth when we push or pull code via git. We will use GitHub for this example
Copy your public key pbcopy < ~/.ssh/id_work_user.pub and then log in to your personal GitHub account:

Go to Settings
Select SSH and GPG keys from the menu to the left.
Click on New SSH key, provide a suitable title, and paste the key in the box below
Click Add key — and you’re done!

Repeat the above steps for the other keys generated for other accounts in the above step
Setting up and usage

The SSH-Agent way

To use the above keys for auth we need to register with the ssh-agent on our machine. Ensure ssh-agent is running on the machine by using this command
eval "$(ssh-agent -s)"
Now add these agents using the below command
ssh-add ~/.ssh/id_rsa
ssh-add ~/.ssh/id_rsa_work_user1
Usage

To start using ssh-agent, you need to set useremail registered with git. git uses this for authentication, username (does not matter - could be any, please try and see :))
Commands:
git config -l                                    #list the current config
git config --global user.name 'vinayakg'         #set the git username in config globally
git config --global user.email 'vg@work.com'     #set the git useremail in config globally 
With the config set , we need to set the ssh-agent - it only accepts one active key at a time
ssh-add -D && ssh-add ~/.ssh/id_work_user
The above command will delete all existing set keys ssh-agent for ssh-agent and will set the one we want
And you can do a git clone on a new repository and work with it by using our familiar commands
git clone git@github.com:vinayakg/repo
The next time you have to work on many git accounts follow the above steps (git config && ssh-add). It's also possible to create handy aliases in git or in shell to save the number of keystrokes. You need not use the global command with git config if you are working on an existing repository. Its also possible to set email in the local .git/config, but this is not helpful for new repositories
The SSH Config way	(Preferred way)

Here we are going to use the same ssh config that we use for SSH auth while connecting to other machines over cloud. This method needs only changing the url while git clone and setting the url while adding git remote . Also this does not rely on any folder structures or other commands .
The SSH config is at ~/.ssh/config. If this file does not exist for you, please go ahead and create it.
touch ~/.ssh/config 
Now open the editor and add the below config
# Personal account
Host gh                               # used for identifying amongst other accounts
   HostName github.com                # git provider website
   User git                           # default user, no need to change
  #AddKeysToAgent yes                 # we are using many, so we will ignore this 
  UseKeychain yes                     # save to keychain
   IdentityFile ~/.ssh/id_work_user   # private key
   
# Work account-1
Host gh-work    
   HostName github.com
   User git
   IdentityFile ~/.ssh/id_rsa_work_user
We will see below how to use these ==Host== name that we setup
Usage

Now we have 2 accounts configured. Let's say you want to clone code from personal account. Use the below command. This command will set correct git remotes. So we don't have to worry when we switch back after working in another account
git clone git@gh:vinayakg/repo
For second, we can use the similar command
git clone git@gh-work:work/repo
Troubleshooting

Issues with existing git accounts on your machine

The default git account on the machine seems to take precedence and wont let use other git account. To set things fresh, lets clear using below command. git config wont be of so much help
Follow the below steps to reset your existing/previous settings
Step 1

$ git credential-osxkeychain erase
host=github.com
protocol=https
<press return>
<press return>
Step 2

Follow this step if step1 did not work
Go to Launcher ➡️ search box ➡️type git username ➡️ then press delete ❌
Step 3

Now check you ssh-add listing and see the certification that are currently configured. If you see any suspects go ahead and delete them
ssh-add -l lists the attached credentials
ssh-add -D delete all the attached ones
And if you have many or user.email or user.name then go ahead and clear them with the following commands
git config --unset user.email && git config --unset user.name
Permission denied (publickey)

Try to debug and see why the auth is failing using the below command. user is always git (for more details see here) and gh is the alias that we have set (gh translates to github.com)
ssh -vT git@gh
Check if you have the right key on GitHub by using the below command
ssh-add -l -E md5
Change remotes for existing git repositories

If you have existing repository, you can change the remotes using the below command
git remote set-url origin git@gh-work:work/repo
More Tips

You can also use git config with includeIf to set git config for work and personal account, thats a preference; I will leave that for now
[includeIf "gitdir:~/work/"]
		path = ~/work/.gitconfig
And the corresponding config too
[user]
    email = john.doe@company.tld

Learnings & Conclusion

It was real fun learning and experiment all this with many account myself. Also understood the role of ssh-agent and how you don't need the agent for git auth if you use the ssh config
If there are any missing pieces, feel free to let me know
References:

https://stackoverflow.com/questions/4220416/can-i-specify-multiple-users-for-myself-in-gitconfig
https://help.github.com/en/github/authenticating-to-github/generating-a-new-ssh-key-and-adding-it-to-the-ssh-agent#adding-your-ssh-key-to-the-ssh-agent
https://www.freecodecamp.org/news/manage-multiple-github-accounts-the-ssh-way-2dadc30ccaca/
https://help.github.com/en/github/authenticating-to-github/error-permission-denied-publickey