go_aws_ami_cleaner

Lambda Environment Variables

Multiple Tags AMI Filtering

• use the "AmiTag_<name>" as tag key name
• e.g. if the tagging filter requirements are "Name":"Web" and "Solution":"IIS" and "Solution":"Logging", then it should be set as the following:

"AmiTag_Name" : "web",
"AmiTag_Solution" : "IIS;Logging"

key	default value	Description
AMI_AGE	14	Number of days since the creation of the AMI
DRY_RUN	none	Whether to run the script in test mode. True - will procceed with test mode False - will DELETE AMIs and Snapshots !

challenges

lambda

• pick up AWS session from lambda
• pick up environment variables from lambda console into Go

code logic

• check for tags and set default values
• filter AMI images based on "self" tag
• filter AMI images based on tag key name and values
• check age of AMI based on DAYS_OLD variable
• compare and exclude AMIs used in launch configurations
• compare and exclude AMIs used in launch templates
• based on final list of AMIs, get respective snapshot IDs

additional features

• multiple tag keys and values filtering via "envSlice := os.Environ()"

Useful links

https://docs.aws.amazon.com/lambda/latest/dg/golang-envvars.html https://docs.aws.amazon.com/lambda/latest/dg/configuration-envvars.html#configuration-envvars-runtime https://docs.aws.amazon.com/lambda/latest/dg/golang-handler.html

Remember to build your handler executable for Linux!

GOOS=linux GOARCH=amd64 go build -o main main.go zip main.zip main

time format

AWS uses ISO-8601 format

Lambda IAM Role Policies Required

• AWSLambdaBasicExecutionRole
• CustomAMIRole with the following policy

{
    "Version": "2012-10-17",
    "Statement": [
        {
            "Sid": "VisualEditor0",
            "Effect": "Allow",
            "Action": "ec2:CreateTags",
            "Resource": "arn:aws:ec2:*::image/*"
        },
        {
            "Sid": "VisualEditor1",
            "Effect": "Allow",
            "Action": [
                "ec2:DescribeImages",
                "ec2:DeregisterImage",
                "ec2:DeleteSnapshot",
                "ec2:DescribeSnapshotAttribute",
                "autoscaling:DescribeLaunchConfigurations",
                "ec2:DescribeImageAttribute",
                "ec2:DescribeSnapshots"
            ],
            "Resource": "*"
        }
    ]
}