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As we don't require any password to login to your server, we need public key authentication to access your server. So you should create an user with read and write access to the folder you want to perform a git pull command. Follow the instructions below to create an user with proper permission so that you remain safe if something goes wrong.

Create a New User

Once you are logged in as root, we’re prepared to add the new user account that we will use to deploy our projects.

ssh root@SERVER_IP_ADDRESS
adduser deployer

User Permission

usermod -a -G www-data deployer

Verify if that worked

id deployer
groups deployer

chgrp www-data /var/www/path/to/project
chmod -R 764 /var/www/path/to/project

Add Public Key Authentication

The next step in securing your server is to set up public key authentication for your new user. Setting this up will increase the security of your server by requiring a private SSH key to log in.

Generate a Key Pair

If you do not already have an SSH key pair, which consists of a public and private key, you need to generate one. If you already have a key that you want to use, skip to the Copy the Public Key step.

To generate a new key pair, enter the following command at the terminal of your local machine (ie. your computer):

ssh-keygen -t rsa

Assuming your local user is called “localuser”, you will see output that looks like the following:

# ssh-keygen output
Generating public/private rsa key pair.
Enter file in which to save the key (/Users/localuser/.ssh/id_rsa):

Hit return to accept this file name and path (or enter a new name).

Next, you will be prompted for a passphrase to secure the key with. You may either enter a passphrase or leave the passphrase blank.

Note: If you leave the passphrase blank, you will be able to use the private key for authentication without entering a passphrase. If you enter a passphrase, you will need both the private key and the passphrase to log in. Securing your keys with passphrases is more secure, but both methods have their uses and are more secure than basic password authentication.

This generates a private key, id_rsa, and a public key, id_rsa.pub, in the .ssh directory of the localuser’s home directory. Remember that the private key should not be shared with anyone who should not have access to your servers!

Copy the Public Key

After generating an SSH key pair, you will want to copy your public key to your new server. We will cover two easy ways to do this.

Option 1: Use ssh-copy-id

If your local machine has the ssh-copy-id script installed, you can use it to install your public key to any user that you have login credentials for.

Run the ssh-copy-id script by specifying the user and IP address of the server that you want to install the key on, like this:

ssh-copy-id deployer@SERVER_IP_ADDRESS

After providing your password at the prompt, your public key will be added to the remote user’s ~/.ssh/authorized_keys file. The corresponding private key can now be used to log into the server.

Option 2: Manually Install the Key

Assuming you generated an SSH key pair using the previous step, use the following command at the terminal of your local machine to print your public key (id_rsa.pub):

cat ~/.ssh/id_rsa.pub

This should print your public SSH key, which should look something like the following:

# id_rsa.pub contents
ssh-rsa AAAAB3NzaC1yc2EAAAADAQABAAABAQDBGTO0tsVejssuaYR5R3Y/i73SppJAhme1dH7W2c47d4gOqB4izP0+fRLfvbz/tnXFz4iOP/H6eCV05hqUhF+KYRxt9Y8tVMrpDZR2l75o6+xSbUOMu6xN+uVF0T9XzKcxmzTmnV7Na5up3QM3DoSRYX/EP3utr2+zAqpJIfKPLdA74w7g56oYWI9blpnpzxkEd3edVJOivUkpZ4JoenWManvIaSdMTJXMy3MtlQhva+j9CgguyVbUkdzK9KKEuah+pFZvaugtebsU+bllPTB0nlXGIJk98Ie9ZtxuY3nCKneB+KjKiXrAvXUPCI9mWkYS/1rggpFmu3HbXBnWSUdf localuser@machine.local

Select the public key, and copy it to your clipboard.

Add Public Key to New Remote User

Login to your server

ssh deployer@SERVER_IP_ADDRESS

Create a new directory called .ssh if you don’t have any and restrict its permissions with the following commands:

mkdir .ssh
chmod 700 .ssh

Now open a file in .ssh called authorized_keys with a text editor. We will use vi to edit the file:

vi .ssh/authorized_keys

Now insert your public key (which should be in your clipboard) by pasting it into the editor, save and exit with :wq.

Now restrict the permissions of the authorized_keys file with this command:

chmod 600 .ssh/authorized_keys

For detailed tutorial, visit digital ocean’s this article