Loading SSH keys automatically on macOS

If you use macOS, follow these steps to configure the OpenSSH client so you can use your passphrase-protected SSH key without prompts.

Prerequisites

macOS 10.13 or later.

Before you begin

Check if you have any existing SSH keys. Refer to the GitHub Docs article, Checking for existing SSH keys.

If you don’t have an SSH key:

Create one by following the GitHub Docs article, Generating a new SSH key.
Add the new SSH key to your GitHub account, by following the GitHub Docs article, Adding a new SSH key to your GitHub account.

Procedure

Check your home folder for an .ssh subdirectory and check if it contains a config file. Note: .ssh is a hidden subdirectory.
Create the ~/.ssh/config file if it doesn’t exist.
Add the following content to ~/.ssh/config to set the key to load in the authentication agent and specify its use by the target server. Make sure you add this entry before any global settings marked as Host *.
```
Host SERVER_NAME
    UseKeychain yes
    IdentitiesOnly yes
    IdentityFile FILE_PATH        
```
- SERVER_NAME is the server that uses the file specified by IdentityFile. A sample value is github.com.
- FILE_PATH is the path to the SSH file you created. A sample value is ~/.ssh/<FILE>, where <FILE> might be id_rsa, id_ecdsa, id_ed25519, or a custom name.
Example:
```
Host github.com
    UseKeychain yes
    IdentitiesOnly yes
    IdentityFile ~/.ssh/id_ed25519
```
Open the Terminal application.
Load your key file into the ssh-agent, replacing <FILE> with the actual file name of your key, then type your passphrase, if prompted.
```
ssh-add ~/.ssh/<FILE>
```
Example:
```
ssh-add ~/.ssh/id_ed25519
```

Configuration is complete. macOS starts ssh-agent by default, so you can now use the Unity Package Manager to fetch packages from that Git repository over SSH using your passphrase-protected SSH key.