An AMI is a pre-configured template used to launch EC2 instances. It packages together the operating system, installed software, configuration settings, and EBS volume snapshots into a single reusable image.
Instead of setting up a fresh server every time, you create an AMI once and use it to launch as many identical instances as you need — instantly.
Think of it like a cookie cutter. You make the perfect cookie once, then use the cutter to stamp out hundreds of identical ones.
Without AMI:
Launch new EC2
|
Install Java (30 min)
Install database (20 min)
Configure settings (15 min)
Install monitoring (10 min)
|
= 75 minutes per server
Need 10 servers = 12+ hours of setup work
With AMI:
Do the setup once on one instance
|
Create AMI
|
Launch 10 EC2 instances from that AMI
|
= All 10 ready in minutes, identical setup
| Type | Created By | Cost |
|---|---|---|
| Public AMI | AWS | Free (e.g. Amazon Linux, Ubuntu) |
| Your own AMI | You | Free to create and use |
| Marketplace AMI | Third-party vendors | Free or paid |
1. Launch an EC2 instance
2. Install your software and configure settings
3. Stop the instance
4. Go to: Actions → Image and Templates → Create Image
5. AMI is created
Why stop the instance first? Stopping ensures all data is flushed to disk before the snapshot is taken. This gives you a clean, consistent image. You can create an AMI from a running instance, but stopping it first is the safer approach.
EC2 in Zone A → Create AMI → Launch EC2 in Zone B or another Region
(customized) (stored) (identical setup)
AMIs are region-specific by default. If you want to use an AMI in a different region, you need to copy it there first. Once copied, you can launch instances from it in that region.
When an AMI is created, AWS automatically takes EBS snapshots of the attached volumes. These snapshots are what gets used when you launch a new instance from the AMI.