Tags instances with detected platform_version

update-ssm-tags.py

#!/usr/bin/env python
# Original: https://gist.github.com/pjaudiomv/ff5efca41cdb7244ef4416c6097f6a7a
import boto3
import pdb


TAG_PLATFORM_VERSION = 'platform_version'


def get_ssm_by_platform_versions(ssm_res):
    versions = {}
    for instance in ssm_res['InstanceInformationList']:
        if not instance['PlatformVersion'] in versions:
            versions[instance['PlatformVersion']] = []
        versions[instance['PlatformVersion']] += [instance]
    return versions


def main():
    ssm = boto3.client('ssm')
    ec2 = boto3.client('ec2')
    ssm_params = {
        'MaxResults': 50
    }
    while True:
        ssm_res = ssm.describe_instance_information(**ssm_params)
        print(f"Retrieved {len(ssm_res['InstanceInformationList'])} instances from SSM")
        # sort by platform version so there are few ec2 create tags requests
        platform_versions = get_ssm_by_platform_versions(ssm_res)
        for version in platform_versions:
            resources = [
                instance['InstanceId']
                for instance in platform_versions[version]
            ]
            # ec2 create_tags max has a limitation of 1000 resources but we're
            # limited by ssm's max of 50 so no need to paginate
            ec2_res = ec2.create_tags(
                Resources=resources,
                Tags=[{
                    'Key': TAG_PLATFORM_VERSION,
                    'Value': version,
                }]
            )
            print(f'Tagged {len(resources)} instances with {TAG_PLATFORM_VERSION}={version}')
        if 'NextToken' in ssm_res:
            ssm_params['NextToken'] = ssm_res['NextToken']
        else:
            break


if __name__ == "__main__":
    main()