AMI (Amazon Machine Image)
💡 Definition
An Amazon Machine Image (AMI) provides the information required to launch an EC2 instance. It's a template that includes a pre-configured operating system, a server, and other software packages.
🔑 Key Concepts
- Template for Instances: An AMI acts as a template for the root volume of an instance (e.g., an operating system, application server, and applications).
- Consistency: Ensures that all instances launched from the same AMI are identical.
- Customization: You can create your own custom AMIs from running EC2 instances.
- Region-Specific: AMIs are Region-specific. To use an AMI in a different Region, you must copy it to that Region.
⚙️ How it Works
- Choose AMI: Select an AMI (e.g., Amazon Linux 2, Ubuntu, custom) when launching an EC2 instance.
- Launch Instance: The AMI is used to create the root volume of your new EC2 instance.
- Custom AMIs: You can customize an EC2 instance, then create a new AMI from it for future use.
🎯 Use Cases
- Rapid Deployment: Quickly launch many identical instances.
- Standardization: Enforce consistent software configurations across an organization.
- Backup & Recovery: Use AMIs created from existing instances as part of a backup strategy.
💰 Pricing Model
- Free (Public AMIs): Many public AMIs are free to use.
- Paid AMIs: Some AMIs from the AWS Marketplace incur costs (e.g., specialized software).
- Storage: You pay for the storage of your custom AMIs (which are stored in S3).
📝 Exam Tips (CLF-C02)
- AMIs are fundamental for launching EC2 instances.
- They provide the operating system and software base for an instance.
- Region-specific but can be copied.
- Used in Auto Scaling launch templates.
See Also: * EC2 * Instance Types * EBS