Amazon Machine Image (AMI)

Question 1

What are AMIs?

Answer 1

Images of EC2 instances that can launch more EC2 instance.

Question 2

Are AMIs regional, global or AZ based?

Answer 2

AMIs are regional with a unique ID.

Question 3

What kind of permissions can you find in an AMI?

Answer 3

• Default only your account can use it.
  
  • Can be set to be public.
  • Can have specific AWS accounts on the AMI.

Question 4

What is a common use of AMIs?

Answer 4

Can create an AMI from an existing EC2 instance to capture the current config (baking).

Question 5

Describe the lifecycle of AMIs:

Answer 5

1. Launch: EBS volumes are attached to EC2 devices using block IDs.
2. Configure: customize the instance from applications or volume sizes.
3. Create Image or AMI
4. Launch: When launching an instance, the snapshots are used to create new EBS volumes in the AZ of the EC2 instance and contain the same block device mapping.

Question 6

What do AMIs contain?

Answer 6

• Permissions: who can use it, is it public or private

- EBS snapshots are created from attached EBS volumes

Question 7

How are Snapshots referenced inside the AMI?

Answer 7

using block device mapping.

Question 8

What is a block device mapping?

Answer 8

Table of data that links the snapshot IDs that you’ve just created when making that AMI and it has for each one of those snapshots, a device ID that the original volumes had on the EC2 instance.

Question 9

If you create an AMI in a region, can this be used in a different region?

Answer 9

No, AMIs are regional.

Question 10

What is AMI baking?

Answer 10

creating an AMI from a configuration instance, with packages installed, etc.

Question 11

Can you edit an AMI?

Answer 11

An AMI cannot be edited. If you need to update an AMI, launch an instance, make changes, then make new AMI

Question 12

We said that AMIs are regional, what can you do to use an AMI in another region?

Answer 12

AMIs can be copied between regions

Question 13

What is the default permission attached to AMIs?

Answer 13

Only access to your account.

Question 14

Based on what are AMIs billed?

Answer 14

Billing is for the storage capacity for the EBS snapshots the AMI references.

Question 15

Is it recommendable to create AMIs from instances that are running? and why?

Answer 15

No, it is recommendable to create an AMI from instances that are stopped, so all the data is written to the EBS volumes.