Git Setup for Multiple Environments on MacOS

Overview

This repository contains configurations for setting up a Git environment on MacOS using SSH and GPG keys. The configurations are tailored to different working directories where the Git settings change accordingly. This documentation will guide you through the process of generating and configuring SSH and GPG keys from scratch, and explain how to use the provided .gitconfig files and SSH configuration for a seamless development setup.

Setting Up SSH Keys

Generate a New SSH Key

To generate a new SSH key, open your terminal and use the following command:

ssh-keygen -t ed25519 -C "username@example.com"

If you are using a legacy system that doesn't support the Ed25519 algorithm, use:

ssh-keygen -t rsa -b 4096 -C "username@example.com"

Follow the prompts to save the key to the default location (~/.ssh/id_ed25519 for Ed25519 keys). When prompted, you can set a passphrase for additional security.

Adding SSH Key to the SSH Agent

Start the SSH agent in the background:

eval "$(ssh-agent -s)"

Add your SSH private key to the SSH agent:

ssh-add ~/.ssh/id_ed25519

For legacy systems:

ssh-add ~/.ssh/id_rsa

Setting Up GPG Keys

Generate a New GPG Key

To generate a new GPG key, use the following command:

gpg --full-generate-key

Follow the prompts to configure your GPG key. Choose the following options when prompted:

• Kind of key: RSA and RSA
• Key size: 4096 bits
• Key expiration: Choose a suitable expiration period or leave it as "0" for no expiration
• Real name: Your Name
• Email address: username@example.com
• Comment: Optional
• Passphrase: Set a secure passphrase

After generating the key, list your keys to find the key ID:

gpg --list-secret-keys --keyid-format LONG

Export the key:

gpg --armor --export your-key-id

Configuring Git

Main .gitconfig File

Create the main .gitconfig file in your home directory (~/.gitconfig) with the following content:

[user]
  name = Your Name
  email = username@domain.com
  signingkey = your-public-ssh-key-string

[commit]
  gpgsign = true

[gpg]
  format = ssh

[gpg "ssh"]
  program = /Applications/1Password.app/Contents/MacOS/op-ssh-sign

[includeIf "gitdir:~/Sites/acme/"]
  path = ~/Sites/acme/.gitconfig

[includeIf "gitdir:~/Sites/alpha/"]
  path = ~/Sites/alpha/.gitconfig

Directory-Specific .gitconfig Files

For the acme directory (~/Sites/acme/.gitconfig):

[user]
  email = username@acme.com
  signingkey = your-gpg-key-string

[gpg]
  format = openpgp

For the alpha directory (~/Sites/alpha/.gitconfig):

[user]
  email = username@alpha.com
  signingkey = your-gpg-key-string

[gpg]
  format = openpgp

SSH Configuration

Create an SSH config file (~/.ssh/config) with the following content:

# Personal Use
Host github.com
    UseKeychain yes
    AddKeysToAgent yes
    IdentityFile ~/.ssh/your_id_rsa_private_key

# Acme
Host github_acme
    HostName github.com
    UseKeychain yes
    AddKeysToAgent yes
    IdentityFile ~/.ssh/your_acme_id_rsa_private_key

# Alpha
Host github_alpha
    HostName github.com
    UseKeychain yes
    AddKeysToAgent yes
    IdentityFile ~/.ssh/your_alpha_id_rsa_private_key

Usage Instructions

1. Clone the repository: Use your preferred method to clone the repository that contains this configuration setup.

2. Customize .gitconfig and SSH configurations: Edit the .gitconfig and SSH config files with your own details. Replace placeholders like your-public-ssh-key-string, your-gpg-key-string, and paths with your actual information.

3. Work with different directories: The provided configuration automatically applies different Git settings based on the working directory (acme and alpha). Ensure your directory structure matches the configuration (e.g., ~/Sites/acme and ~/Sites/alpha).

4. Commit Signing: Your commits will be signed using the specified GPG key. Ensure your GPG key is added to your GitHub account by following GitHub's guide.

5. SSH Key Usage: Use the appropriate SSH key for different repositories by configuring your remote URLs with the corresponding host (github_acme or github_alpha).