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Lab 01 - Writing Packer Template.md

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Lab: Write a Packer Template

This lab will walk you through updating a Packer HCL Template. It uses the amazon-ebs source to create a custom image in the us-west-2 region of AWS.

Duration: 30 minutes

  • Task 1: Create a Source Block
  • Task 2: Validate the Packer Template
  • Task 3: Create a Builder Block
  • Task 4: Build a new Image using Packer

Creating a Packer Template

mkdir packer_templates
cd packer_templates

Task 1: Create a Source Block

Source blocks define what kind of virtualization to use for the image, how to launch the image and how to connect to the image. Sources can be used across multiple builds. We will use the amazon-ebs source configuration to launch a t3.micro AMI in the us-west-2 region.

Step 1.1.1

Create a aws-ubuntu.pkr.hcl file with the following Packer source block and required_plugins.

packer {
  required_plugins {
    amazon = {
      source  = "github.com/hashicorp/amazon"
      version = "~> 1"
    }
  }
}

source "amazon-ebs" "ubuntu" {
  ami_name      = "packer-ubuntu-aws-{{timestamp}}"
  instance_type = "t3.micro"
  region        = "us-west-2"
  source_ami_filter {
    filters = {
      name                = "ubuntu/images/*ubuntu-jammy-22.04-amd64-server-*"
      root-device-type    = "ebs"
      virtualization-type = "hvm"
    }
    most_recent = true
    owners      = ["099720109477"]
  }
  ssh_username = "ubuntu"
}

Step 1.1.2

The packer init command is used to download Packer plugin binaries. This is the first command that should be executed when working with a new or existing template. This command is always safe to run multiple times.

packer init aws-ubuntu.pkr.hcl

Task 2: Validate the Packer Template

Packer templates can be auto formatted and validated via the Packer command line.

Step 2.1.1

Format and validate your configuration using the packer fmt and packer validate commands.

packer fmt aws-ubuntu.pkr.hcl 
packer validate aws-ubuntu.pkr.hcl

Task 3: Create a Builder Block

Builders are responsible for creating machines and generating images from them for various platforms. They are use in tandem with the source block within a template.

Step 3.1.1

Add a builder block to aws-ubuntu.pkr.hcl referencing the source specified above. The source can be referenced usin the HCL interpolation syntax.

build {
  sources = [
    "source.amazon-ebs.ubuntu"
  ]
}

Task 4: Build a new Image using Packer

The packer build command is used to initiate the image build process for a given Packer template. For this lab, please note that you will need credentials for your AWS account in order to properly execute a packer build. You can set your credentials using environment variables, using aws configure if you have the AWSCLI installed, or embed the credentials in the template.

Example using environment variables on a Linux or macOS:

export AWS_ACCESS_KEY_ID=<your access key>
export AWS_SECRET_ACCESS_KEY=<your secret key>
export AWS_DEFAULT_REGION=us-west-2

Example via Powershell:

PS C:\> $Env:AWS_ACCESS_KEY_ID="<your access key>"
PS C:\> $Env:AWS_SECRET_ACCESS_KEY="<your secret key>"
PS C:\> $Env:AWS_DEFAULT_REGION="us-west-2"

Step 4.1.1

Run a packer build for the aws-ubuntu.pkr.hcl template.

packer build aws-ubuntu.pkr.hcl

Packer will print output similar to what is shown below.

amazon-ebs.ubuntu: output will be in this color.

==> amazon-ebs.ubuntu: Prevalidating any provided VPC information
==> amazon-ebs.ubuntu: Prevalidating AMI Name: packer-ubuntu-aws-1620827902
    amazon-ebs.ubuntu: Found Image ID: ami-0dd273d94ed0540c0
==> amazon-ebs.ubuntu: Creating temporary keypair: packer_609bdefe-f179-a11c-3bfd-6f4deda66c99
==> amazon-ebs.ubuntu: Creating temporary security group for this instance: packer_609bdf00-c182-00a1-e516-32aea832ff9e
==> amazon-ebs.ubuntu: Authorizing access to port 22 from [0.0.0.0/0] in the temporary security groups...
==> amazon-ebs.ubuntu: Launching a source AWS instance...
==> amazon-ebs.ubuntu: Adding tags to source instance
    amazon-ebs.ubuntu: Adding tag: "Name": "Packer Builder"
    amazon-ebs.ubuntu: Instance ID: i-0c9a0b1b896b8c95a
==> amazon-ebs.ubuntu: Waiting for instance (i-0c9a0b1b896b8c95a) to become ready...
==> amazon-ebs.ubuntu: Using ssh communicator to connect: 34.219.135.12
==> amazon-ebs.ubuntu: Waiting for SSH to become available...
==> amazon-ebs.ubuntu: Connected to SSH!
==> amazon-ebs.ubuntu: Stopping the source instance...
    amazon-ebs.ubuntu: Stopping instance
==> amazon-ebs.ubuntu: Waiting for the instance to stop...
==> amazon-ebs.ubuntu: Creating AMI packer-ubuntu-aws-1620827902 from instance i-0c9a0b1b896b8c95a
    amazon-ebs.ubuntu: AMI: ami-0561bdc79bbb8f5a0
==> amazon-ebs.ubuntu: Waiting for AMI to become ready...
==> amazon-ebs.ubuntu: Terminating the source AWS instance...
==> amazon-ebs.ubuntu: Cleaning up any extra volumes...
==> amazon-ebs.ubuntu: No volumes to clean up, skipping
==> amazon-ebs.ubuntu: Deleting temporary security group...
==> amazon-ebs.ubuntu: Deleting temporary keypair...
Build 'amazon-ebs.ubuntu' finished after 3 minutes 16 seconds.

==> Wait completed after 3 minutes 16 seconds

==> Builds finished. The artifacts of successful builds are:
--> amazon-ebs.ubuntu: AMIs were created:
us-west-2: ami-0561bdc79bbb8f5a0

Note: This lab assumes you have the default VPC available in your account. If you do not, you will need to add the vpc_id and subnet_id. The subnet will need to have public access and a valid route to an Internet Gateway.

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