deployer.py

import urllib
import boto3
import datetime
import json
import unittest

print('Loading function')
s3 = boto3.client('s3')
lambda_client = boto3.client('lambda')

def handler(event, context):
    bucket = event['Records'][0]['s3']['bucket']['name']
    key = urllib.unquote_plus(
        event['Records'][0]['s3']['object']['key']).decode('utf8')
    version = event['Records'][0]['s3']['object']['versionId']
    # This is kind of jank, but hey!  Maybe a good use case for S3 metadata in the future.
    is_prod = key.endswith('_PROD.zip')
    if not key.endswith('.zip'):
        raise Exception('S3 objects must be zips!')

    try:
        deploy_function(bucket, key, version, is_prod)
        return True
    except Exception as e:
        print(e)
        print('Error getting object {} from bucket {}. Make sure they exist and your bucket is in the same region as this function.'.format(key, bucket))
        raise e

def deploy_function(bucket, key, version, publish, runtime='python2.7', role='', handler='handler.handler', timeout=60, memory_size=128):
    name = key.replace('/', '_').replace('.zip', '')
    description = ' - '.join([function_name, version])
    lambda_function = lambda_client.get_function(FunctionName=function_name)
    if lambda_function is None:
        lambda_client.create_function(
            FunctionName=name,
            Runtime=runtime,
            Role=role,
            Handler=handler,
            Code={
                'S3Bucket': bucket,
                'S3Key': key,
                'S3ObjectVersion': version
            },
            Description=description,
            Timeout=timeout,
            MemorySize=memory_size,
            Publish=publish
        )
    else:
        lambda_client.update_function_code(
            FunctionName=name,
            S3Bucket=bucket,
            S3Key=key,
            S3ObjectVersion=version,
            Publish=publish
        )