How to Add New SSH Users with Public Key in Linux AMI Images using Packer

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Introduction

This article provides an example of adding new SSH users with public keys to the AMI image built by Packer.

Prerequisites

• Packer CLI
• AWS account

Procedure

1. Generate an SSH key and copy the generated id_rsa.pub to another folder, for example, assets/:

   $ ssh-keygen
   
   Output:
   Your identification has been saved in /your_home/.ssh/id_rsa
   Your public key has been saved in /your_home/.ssh/id_rsa.pub

   $ mkdir assets
   $ cp /your_home/.ssh/id_rsa.pub ./assets/

2. In the build block, add a file provisioner to upload id_rsa.pub to /tmp folder and shell provisioner to create a new SSH user:

     provisioner "file" {
       source = "assets/"
       destination = "/tmp"
     }
   
     provisioner "shell" {
       inline = [
         "echo 'Create newuser user and group'",
         "sudo groupadd newuser",
         "sudo useradd -m -g newuser -s /bin/bash -c \"Newuser\" newuser",
         "sudo runuser -l newuser -c 'mkdir /home/newuser/.ssh'",
         "sudo cp /tmp/id_rsa.pub /home/newuser/.ssh/",
         "sudo chown newuser:newuser /home/newuser/.ssh/id_rsa.pub",
         "sudo chmod 600 /home/newuser/.ssh/id_rsa.pub",
         "sudo chmod 700 /home/newuser/.ssh/"
       ]
     }

Additional Information

• File Provisioner - Directory Uploads
• Shell Provisioner