Getting Started with AMIs for EC2 Instances in AWS

Introduction

Think of an Amazon Machine Image (AMI) as a template of a virtual machine, including an operating system and any additional software or configurations we require.AMI allows us to create a customized virtual computing environment. Let us understand AMIs better.

Why Do We Need AMIs?

• Customization: AMIs provide a way to package our software, configurations, monitoring tools, and more. This means we can create an environment tailored to our specific needs.
• Efficiency: Utilizing AMIs can significantly reduce boot and configuration time for new instances since everything is pre-packaged.
• Disaster recovery: AMIs provide a snapshot of an instance that includes the operating system, the installed software, and all the instance configurations. This allows for the rapid provisioning of new instances with the same setup, which is crucial for disaster recovery.

Important Features of AMIs

• Region Specific: AMIs are built for specific AWS regions, but they can be copied across regions for broader accessibility.
• Versatility in Launch Options: We can launch EC2 instances using:
  • Public AMI: Provided by AWS and available to all users.
  • Our own AMI: Created and maintained by you for your specific needs.
  • AWS Marketplace AMI: Developed by third-party vendors, these can be free or sold to AWS users.

• Different Ways to Create AMIs

  • Manually: See the section Creating an AMI for manual creation steps.
  • Automated Tools: AWS provides automated tools such as AWS Systems Manager and AWS Lambda, which can automate the process of creating and managing AMIs.
  • Third-Party Tools: There are also third-party tools available that can provide more advanced features or a different workflow for AMI creation and management.

AMI Lifecycle

The lifecycle of an AMI encompasses the creation, management, and deprecation phases. Here's an overview of each phase:

1. Creation: The lifecycle begins when we create an AMI from an existing Amazon EC2 instance, a snapshot, or by importing a virtual machine image from our local environment. When creating an AMI, we specify the instance's root volume and any additional storage volumes to include. This AMI can be made private, shared with specific AWS accounts, or made public to the AWS community.

2. Management:

   • Sharing AMIs: After creation, we can share your AMI with other AWS accounts or make it public. This allows others to launch instances using our AMI.
   • Updating AMIs: If we need to update software, patches, or make any changes to the configuration of our AMI, we typically do this by launching an instance from the AMI, making the changes, and then creating a new AMI. This results in a new AMI ID.
   • Deregistering AMIs: If an AMI is no longer needed, we can deregister it. Deregistering an AMI does not delete the snapshots on which it is based. We need to delete those snapshots manually to avoid incurring storage costs.
   • Copying AMIs: We can copy AMIs within or across AWS regions. This is useful for scaling our application geographically or for redundancy purposes.

3. Deprecation:

   • When an AMI is no longer required or has been superseded by a newer version, it can be deprecated. Deprecation involves deregistering the AMI and then deleting the underlying snapshots if they are no longer needed. 

4. Deletion:

   • Deleting Snapshots: After deregistering an AMI, we should manually delete the associated EBS snapshots to free up space and reduce costs. Deleting an AMI does not automatically delete the snapshots.

Proper management of AMIs, including version control and lifecycle policies, is crucial for maintaining a clean, efficient, and cost-effective AWS environment.

Creating an AMI

AMI Process from an EC2 Instance

1. Start with EC2: Begin by launching an EC2 instance. This instance is the foundation where you'll add your desired operating system, applications, and configurations.
2. Customization: Customize this instance to meet your requirements. This could involve installing software, setting up configurations, or adding monitoring tools.
3. Stop the Instance: Once your customization is complete, stop the instance. This step is crucial for data integrity and ensures no data is lost during the AMI creation.
4. Build the AMI: From your stopped instance, you can create an AMI. This process also creates EBS (Elastic Block Store) snapshots, which are backups of your instance's volumes.
5. Launch New Instances: Finally, you can use your newly created AMI to launch other instances. This process is much quicker as the instances are pre-configured with your settings.

Additional Notes

• EC2 Image Builder: AWS EC2 Image Builder is a fully managed service that makes it easier to automate the creation, management, and deployment of customized, secure, and up-to-date "golden" server images that are pre-installed and pre-configured with software and settings to meet specific IT standards.
  • Note: The term "golden server" or more commonly "golden image" refers to a template of a virtual machine (VM), server, or hard disk drive that has been pre-configured with an operating system, software applications, and settings tailored to meet the specific needs of an organization or project.

• AMI Permissions: We can share AMIs with specific AWS accounts or make them public for broader accessibility. 

• Security Practices: When creating AMIs, prioritize security to protect our data. This includes removing sensitive information, closing unnecessary ports, and ensuring the latest security patches are applied. For public AMIs, extra caution is necessary to avoid exposing private data or security vulnerabilities.

• Cost Management: AMIs and their associated EBS snapshots incur costs for storage on AWS.Knowing how to efficiently manage and clean up unused AMIs and snapshots can help in controlling AWS expenses.

• Backup Strategies: We need to create them regularly, manage their versions, and ensure they are readily accessible for recovery purposes.

Conclusion

In conclusion, AMIs are a fundamental aspect of working with AWS, offering customization, efficiency, and a variety of launch options. Whether you're preparing for an AWS exam or looking to streamline your cloud infrastructure, mastering AMIs is a valuable skill.

See more

We can explore the following advanced concepts related to AMIs if we aim to master them:

• AMI Virtualization Types: docs.aws.amazon.com/AWSEC2/latest/UserGuide/virtualization_types.html
• Boot mode of AMIs: docs.aws.amazon.com/AWSEC2/latest/UserGuide/ami-boot.html
• User-provided kernels: docs.aws.amazon.com/AWSEC2/latest/UserGuide/UserProvidedKernels.html
• AMI types: docs.aws.amazon.com/AWSEC2/latest/UserGuide/ComponentsAMIs.html
• EC2 Image Builder: docs.aws.amazon.com/imagebuilder/latest/userguide/what-is-image-builder.html
• Create EC2 Image Pipeline: docs.aws.amazon.com/imagebuilder/latest/userguide/start-build-image-pipeline.html
• Encrypted AMIs: cloudericks.com/blog/understanding-ami-encryption-and-sharing-across-aws-accounts.