Saturday, November 13, 2021

[SOLVED] Get latest AMI ID for AWS instance

Issue

I wanted to fetch the latest ami id for AWS Linux machine while creating an ec2 instance for an autoscaling architecture.

I was trying the aws cli to get the images types, but it would print out a lot of information if I used the describe-images command.

My requirement was to get only the image id, so that I could use it to create a launch configuration or launch an instance with the latest ami-id.


Solution

A little-known recent feature is the ability to Query for the latest Amazon Linux AMI IDs using AWS Systems Manager Parameter Store | AWS Compute Blog.

The namespace is made up of two parts:

  • Parameter Store Prefix (tree): /aws/service/ami-amazon-linux-latest/
  • AMI name alias: (example) amzn-ami-hvm-x86_64-gp2

These:

aws ec2 describe-images --owners amazon --filters "Name=name,Values=amzn*" --query 'sort_by(Images, &CreationDate)[].Name'

Get-EC2ImageByName -Name amzn* | Sort-Object CreationDate | Select-Object Name

can be changed into:

aws ssm get-parameters --names /aws/service/ami-amazon-linux-latest/amzn2-ami-hvm-x86_64-gp2 --region us-east-1 

Get-SSMParameter -Name /aws/service/ami-amazon-linux-latest/amzn2-ami-hvm-x86_64-gp2 -region us-east-1

Plus, it can be used in a CloudFormation template:

# Use public Systems Manager Parameter
 Parameters :
 LatestAmiId :
 Type : 'AWS::SSM::Parameter::Value<AWS::EC2::Image::Id>'
 Default: ‘/aws/service/ami-amazon-linux-latest/amzn2-ami-hvm-x86_64-gp2’

Resources :
 Instance :
 Type : 'AWS::EC2::Instance'
 Properties :
 ImageId : !Ref LatestAmiId


Answered By - John Rotenstein
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