Day 29 – Introduction to Packer – Part 1

Welcome to Day 29 of 101 Days of DevOps. The topic for today is Introduction to Packer — Part 1.

What is Packer?

Packer is easy to use and automates the creation of any machine image.

• It integrates natively with a bunch of configuration management systems, e.g., Ansible, Puppet.
• Packer is cross-platform(Linux/Window)
• Packer uses a JSON template file and lets you define immutable infrastructure.
• It’s written in the GO language.

Installing Packer on Ubuntu

curl -fsSL https://apt.releases.hashicorp.com/gpg | sudo apt-key add -

sudo apt-add-repository "deb [arch=amd64] https://apt.releases.hashicorp.com $(lsb_release -cs) main"

sudo apt-get update && sudo apt-get install packer

• Some Packer Options

packer
Usage: packer [--version] [--help] <command> [<args>]

Available commands are:
    build           build image(s) from template
    console         creates a console for testing variable interpolation
    fix             fixes templates from old versions of packer
    fmt             Rewrites HCL2 config files to canonical format
    hcl2_upgrade    transform a JSON template into an HCL2 configuration
    init            Install missing plugins or upgrade plugins
    inspect         see components of a template
    validate        check that a template is valid
    version         Prints the Packer version

Packer Template

• Divided into three parts, each of them is a json array, so you can have as many as you want in each section.

Builders

• Use to generate an image, and it’s provider-specific. E.g., if you create an image for AWS, your builder will tell the packer which AMI to start with and what region to create that AMI.

  "builders": [{
    "type": "amazon-ebs",
    "access_key": "{{user `aws_access_key`}}",
    "secret_key": "{{user `aws_secret_key`}}",
    "region": "us-east-1",
    "instance_type": "t2.micro",
    "ssh_username": "ubuntu",
    "ami_name": "packer-example {{timestamp}}"
  }]

Provisioners

• It let you customize your images.
• These can be scripts(bash or PowerShell)or your existing configuration management system(e.g., chef, puppet, salt stack, and Ansible) or files where you can upload a file to the running instance for capturing things, e.g., config files, binaries, etc.

    "provisioners": [
        {
            "type": "shell",
            "script": "./example.sh"
        }
    ]

Post-Processors

• Let’s integrate with other services like Docker. E.g., it will let you upload an image to dockerhub.

{
  "post-processors": [
    [
      "compress",
      { "type": "upload", "endpoint": "http://example.com" }
    ]
  ]
}

If you like to dig deeper into the AWS concept, please feel free to check my book.

Looking forward to you guys joining this journey and spend a minimum of an hour every day for the next 101 days on DevOps work and post your progress using any of the below mediums.

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