How do you build robust, idempotent automation scripts using the AWS CLI or SDKs that can safely be run multiple times without causing errors or duplicate resources?

Building idempotent automation involves checking whether a resource already exists before attempting to create it, using conditional logic based on the API's own responses, leveraging built in idempotency tokens that many AWS APIs support to safely retry a request without creating duplicate resources, and designing scripts to gracefully handle already exists errors as a successful outcome rather than treating them as failures, ensuring the same script can be safely rerun during a failed deployment recovery without unwanted side effects.

import boto3
client = boto3.client('ec2')
try:
    client.create_key_pair(KeyName='my-key')
except client.exceptions.ClientError as e:
    if 'InvalidKeyPair.Duplicate' not in str(e):
        raise