python-lambda-local

Run lambda function on local machine

Prepare development environment

Please use a newly created virtualenv for python2.7.

Installation

Within virtualenv, run the following command.

$ cd $PROJECT_ROOT
$ pip install ./

This will install the package with name python-lambda-local in the virtualenv. Now you can use the command python-lambda-local to run your AWS Lambda function written in Python on your own machine.

Usage

Run python-lambda-local -h to see the help.

usage: python-lambda-local [-h] [-l LIBRARY_PATH] [-f HANDLER_FUNCTION]
                           [-t TIMEOUT]
                           FILE EVENT

Run AWS Lambda function written in Python on local machine.

positional arguments:
  FILE                  Lambda function file name
  EVENT                 Event data file name.

optional arguments:
  -h, --help            show this help message and exit
  -l LIBRARY_PATH, --library LIBRARY_PATH
                        Path of 3rd party libraries.
  -f HANDLER_FUNCTION, --function HANDLER_FUNCTION
                        Lambda function handler name. Default: "handler".
  -t TIMEOUT, --timeout TIMEOUT
                        Seconds until lambda function timeout. Default: 3

Prepare development directory

Project directory structure

Suppose your project directory is like this:

├── event.json
├── lib
│   ├── rx
│   │   ├── abstractobserver.py
│   │   ├── ... (package content of rx)
...
│   │       └── testscheduler.py
│   └── Rx-1.2.3.dist-info
│       ├── DESCRIPTION.rst
│       ├── METADATA
│       ├── metadata.json
│       ├── pbr.json
│       ├── RECORD
│       ├── top_level.txt
│       ├── WHEEL
│       └── zip-safe
└── test.py

In the handler's code is in test.py and the function name of the handler is handler. The source depends on 3rd party library rx and it is install in the directory lib. The test event of json format is in event.json file.

Content of test.py:

from rx import Observable


def handler(event, context):
    xs = Observable.from_([1, 2, 3, 4, 5, 6])
    ys = xs.to_blocking()
    zs = (x*x for x in ys if x > 3)
    for x in zs:
        print x

Content of event.json:

{
  "key": "value"
}

Run the lambda function

Within the project root directory, you can run the lambda function with the following command

python-lambda-local -l lib/ -f handler -t 5 test.py event.json

The output will be like:

[INFO 2015-10-16 18:21:14,774] Event: {'key': 'value'}
[INFO 2015-10-16 18:21:14,774] START RequestId: 324cb1c5-fa9b-4f39-8ad9-01c95f7d5744
16
25
36
[INFO 2015-10-16 18:21:14,775] END RequestId: 324cb1c5-fa9b-4f39-8ad9-01c95f7d5744
[INFO 2015-10-16 18:21:14,775] RESULT: None