Baking Amazon Machine Images (AMIs) offers significant advantages in deploying preconfigured EC2 instances quickly and efficiently. It eliminates the need for repetitive setup tasks and is crucial for scaling infrastructure. In this blog post, we will explore two powerful tools, Packer and EC2 Image Builder, that facilitate automated, DevOps-friendly AMI baking processes.

Packer: Simplifying AMI Creation Automation

When it comes to creating Amazon Machine Images (AMIs) in AWS, Packer has been a reliable and widely adopted tool for a significant period. It remains a popular choice for most users due to its versatility, ease of use, and open-source nature. In this blog post, we will revisit Packer and highlight its enduring value as a tool for building AMIs. Whether you are a seasoned user or new to Packer, its simplicity and flexibility make it an attractive solution for AMI creation.

EC2 Image Builder: Managed AMI Baking Workflow

Since its introduction in late 2019, EC2 Image Builder has emerged as a distinct alternative to Packer for AMI baking in AWS. Unlike Packer, EC2 Image Builder adopts a pipeline-based approach, providing a comprehensive solution for building AMIs. While it may not replace a full-fledged CodePipeline solution, EC2 Image Builder offers a lightweight and efficient pipeline specifically designed for AMI creation. In this blog post, we will explore EC2 Image Builder's unique features and highlight its role as a dedicated tool for AMI baking.

Why are we moving from Packer to EC2 Image Builder

A golden image is essentially a bespoke base image you create for your instances. It should come pre-baked with the latest software and security patches you need.

Building a golden image is a deceptively tricky problem. The old diagram below is borrowed from a 2017 AWS blog post to give you an idea of complexity involved in running Packer:

While the implementation will vary, this would be the typical architecture you would find.

The problems with this approach are:

• How do we schedule the image builds?
• How do we test the image still works?
• How do we distribute the AMI after it has been created?

The real power of EC2 Image Builder is that it encompasses all of these features into a single managed service.

Advantages of moving from Packer to EC2 Image Builder

Moving from Packer to EC2 Image Builder can offer several advantages and benefits. Here are some reasons why you might consider transitioning from Packer to EC2 Image Builder:

1. Pipeline-Oriented AMI Building: EC2 Image Builder distinguishes itself from Packer by offering a more structured, pipeline-based approach to AMI creation. With EC2 Image Builder, you can define a sequence of build components, tests, and validations, creating a well-defined process for AMI generation. This pipeline-oriented approach simplifies the creation, management, and automation of AMI builds.
2. Complete Solution for AMI Building: While Packer focuses primarily on the AMI creation process, EC2 Image Builder provides a more comprehensive solution. It incorporates various stages in the AMI lifecycle, including base image selection, customization, testing, and distribution. EC2 Image Builder streamlines the entire workflow, offering a one-stop solution for building, validating, and deploying AMIs.
3. Lightweight and Easy to Use: EC2 Image Builder offers a lightweight and user-friendly experience, making it accessible to both experienced and novice users. With its intuitive interface, you can define and manage AMI build pipelines effortlessly. EC2 Image Builder can be scheduled to run on a regular basis or initiated manually, ensuring flexibility and convenience in your AMI creation process.
4. No Additional Costs: One of the advantages of migrating to EC2 Image Builder is that there are no additional costs associated with using the service itself. EC2 Image Builder utilizes the underlying AWS resources, and standard pricing applies for those resources such as EC2 instances, EBS volumes, and S3 storage. This allows you to take advantage of EC2 Image Builder's capabilities without incurring additional expenses.
5. Compliance and Security Considerations: EC2 Image Builder places a strong emphasis on compliance and security. It provides built-in checks and validations to ensure AMIs adhere to best practices and compliance standards. EC2 Image Builder enables you to define security configurations, apply patches, and incorporate security scans, strengthening the security posture of your AMIs.
6. Scalability and Automation: With its pipeline-based approach, EC2 Image Builder supports scaling AMI builds efficiently. You can easily scale your AMI pipelines to handle larger workloads, allowing you to accommodate growing infrastructure needs. Moreover, EC2 Image Builder's automation capabilities reduce manual intervention, ensuring consistent and repeatable AMI builds.

OS Image Build Workflow

Here’s a basic workflow of how Image Builder creates a new Amazon Machine Image (AMI) from base image:

Utilize the Image Builder with the AWS console, AWS CLI, or APIs in order to create images in your AWS account. When used with the AWS console, Image Builder provides a step-by-step wizard covering the following steps:

Step 1: Provide starting artifacts: Start with a base OS image — either AWS Managed images or Custom AMI’s. Customers can also import their on-premises VM Images or snapshots and create Custom AMIs within AWS to use as an Image Builder input.

Step 2: Add and remove software, setting, and scripts: Select additional pieces of software for installation along with the required answer files, scripts, and settings from registered repositories and S3 buckets. Apply either your own or AWS-provided security settings (e.g., Amazon Inspector).

Step 3: Secure image: Use AWS-provided and/or custom templates.

Step 4: Run tests: Run your own tests and AWS-provided tests to validate images before deployment.

Step 5: Distribute images to accounts and regions: New AMI is generated and distributed across user-defined AWS regions.

Understanding Image Builder building blocks

In order to setup an Image Builder environment, you must understand these terminologies:

1. Components: A component defines the step sequence required to either customize an instance prior to image creation (a build component), or to test an instance launched from the created image (a test component). After they are created, one or more components are grouped together via an image recipe or container recipe to define the plan for building and testing a virtual machine or container image.

2. Image recipes: A document defining the source image and the components applied to the source image in order to produce the desired configuration for the output AMI image.

3. Image pipelines: An image pipeline provides an automation framework for building secure AMIs and container images on AWS. The Image Builder image pipeline is associated with an image recipe or container recipe defining the build, validation, and test phases for an image build lifecycle.

4. Infrastructure Configuration: Image Builder launches ephemeral EC2 instances in your account in order to customize images and run validation tests. Create infrastructure configuration to specify the infrastructure details for the ephemeral instances that will run in your AWS account during the build process. Also, enable settings such as exporting image builder logs to Amazon S3 and disabling EC2 Instance Termination to help diagnose failures.

5. Distribution settings: Configuration that allows sharing AMI ID with other AWS accounts.

Conclusion

Migrating from HashiCorp Packer to EC2 Image Builder offers a streamlined and feature-rich approach to AMI creation and management. By leveraging EC2 Image Builder's resources, such as AWS Managed Components, Image Builder Pipelines, and Distribution Settings, you can enhance productivity, reduce operational overhead, and ensure compliance with image creation standards. Furthermore, the absence of additional costs for EC2 Image Builder makes it an attractive choice for organizations looking to optimize their AMI creation processes within the AWS ecosystem.