Delete the versions of the calls except the last 4

delete-versions-of-aws-lambdas.py

from __future__ import absolute_import, print_function, unicode_literals
import boto3


def clean_old_lambda_versions():
    client = boto3.client('lambda')
    functions = client.list_functions()['Functions']
    print("Quantity of functions" + str(len(functions)))
    for function in functions:
        print(function['Version'])
        versions = client.list_versions_by_function(FunctionName=function['FunctionArn'])['Versions']
        print("Quantity of versions" + str(len(versions)))

        lastFour = versions[-4:]   
        for version in versions:
            if version not in lastFour:
                print(version['Version'])
                if version['Version'] != function['Version']:
                    arn = version['FunctionArn']
                    print('delete_function(FunctionName={})'.format(arn))
                    client.delete_function(FunctionName=arn)  # uncomment me once you've checked


if __name__ == '__main__':
    clean_old_lambda_versions()