Phase Verbs / Action Phrases
| Phrase | Meaning |
|---|---|
| customize (an EC2 instance) | configure software, OS settings, monitoring tools etc. |
| build (an AMI) | capture a running EC2 configuration into a reusable image |
| launch (from AMI) | create a new EC2 instance using an AMI as a template |
| copy (AMI across region) | replicate an AMI to another AWS region |
| package (software into AMI) | pre-install software into an AMI to reduce boot time |
Technical Vocabulary
| Term | Definition |
|---|---|
| AMI (Amazon Machine Image) | A template for launching EC2 instances; includes OS, config, and optional software |
| Public AMI | Provided by AWS (e.g., Amazon Linux 2); free to use |
| Custom AMI | Built by you from an existing EC2 instance; you maintain it |
| Marketplace AMI | Built and sold by third-party vendors via AWS Marketplace; often has pre-installed commercial software |
| Data integrity | Consistency of stored data; stopping the instance before creating an AMI ensures a clean capture |
| EBS Snapshot | Created behind the scenes when you build an AMI from a running instance |
Key Concepts
What is an AMI?
- Amazon Machine Image = template for launching EC2 instances
- Contains: OS, software, configuration, monitoring agents
- Think of it as a “golden image” of a configured EC2 instance
- Region-specific; must be copied to use in another region
AMI Types
| Type | Source | Use Case |
|---|---|---|
| Public AMI (AWS) | Provided by AWS | Default starting point (Amazon Linux 2, Windows, Ubuntu) |
| Custom AMI | Built by you | Pre-configured with your software; faster launch times |
| Marketplace AMI | Third-party vendors | Pre-packaged commercial software (e.g., NGINX, databases) |
AMI Process (How to Build a Custom AMI)
- Launch an EC2 instance
- Customize it (install software, configure settings)
- Stop the instance (recommended for data integrity)
- Create AMI → AWS automatically creates EBS snapshots behind the scenes
- Launch new instances from your custom AMI (in same or different AZ/region)
Why Use a Custom AMI?
- Faster boot time: Software is pre-installed — no need to run User Data scripts
- Consistency: Every new instance starts with the same known-good configuration
- Cross-AZ replication: Build once in AZ-A, launch copies in AZ-B
AMI and Regions
- AMIs are region-scoped; you can copy them to other regions
- Common pattern: Build in one region, copy for DR or global expansion
Exam Tips
- AMI = EC2 launch template (OS + config + optional software)
- Creating a custom AMI also creates EBS snapshots internally
- AMIs are region-specific — copy to use in another region
- Public AMIs are free; Marketplace AMIs may have licensing costs
- Custom AMI = faster boot/config because software is pre-packaged
- Recommended: stop the instance before building AMI for data integrity