Disclaimer

• theScore does not use this in production. This library was built when AWS Lambda was stuck at 2.7 for a long time and we wanted to use Python 3. Two days after this idea succeeded, AWS announced support for 3.6 :). However, this may still be of use to those who want to use versions other than the official version

Marol

Run any Python 3 version instead of the standard AWS Lambda Python version.

Python 3 version support

• Tested on 3.6.1, 3.6.2, 3.6.3

Instructions

You pass in your handler file(e.g. my_handler.py) and it returns back:

• handler_python3.py. my_handler.py is renamed to handler_python3.py and code is added to make it callable from a python2 handler
• handler.py. This is the Python2 module that is called which delegates to the Python3 handler file
• path to marol_venv folder. This is the folder which contains all the executables for the Python version that you chose.

To use Marol, your my_handler.py will have the following constraints:

• The handler function should be named handler
• The file cannot be called handler.py(This is reserved for the Python2 handler which will execute the Python3 handler
• There should be no main statement in the handler file
• One should not have functions with the following names:
  1. load
  2. read_execution_uuid

Installation

Pre-requisites

• Ensure docker is installed and running on the machine where Marol is executed.

Mac OS X

• Open the terminal and run /Applications/<Python Version>/Install Certificates.command

Usage

Your deployment scripts for lambda should specify handler.py and handler as the starting point for your Lambda function. This is the Python2 handler returned by Marol which calls your modified Python3 handler.

import marol
my_project_site_packages = ...
my_deploy_lambda_function(lambda_name,
                          marol.get_lambda_files('~/mypath/mypy3handler.py', '3.6.1') + my_project_site_packages,
                          'lambda_s3_exec_role',
                          128,
                          300,
                          lambda_description='Test for Python 3',
                          handler_name="handler",
                          handler_file="handler.py",
                          region_name='us-east-1')

get_lambda_files will check MAROL_HOME if marol_venv exists for the particular version that you want. If it exists, you will get back that path. If it does not exist,marol will

• download the python source
• build the binaries using a docker image which mirrors the AWS Lambda environment
• create a basic marol_venv and store it at MAROL_HOME/staging/<python_version>

Future Work

• Some of the context attributes are not supported yet.
• Ensure that the context object is updated for future changes

Notes

• This adds an additional 2-5 seconds to execution time.
• This only provides the core Python libraries.
• Default Marol home is <HOME>/.marol.
• It will create marol_venv in <HOME>/.marol/staging/<python_version>

Notes for those thinking about security

• This uses an unofficial docker image