ratatoskr

Ratatoskr is a library written in Python to make the development of AWS Lambdas easier and more secure. It supports implementing "singleshot" operations that can be reached from an AWS Lambda function and validating the input parameters to avoid unnecessary boilerplate for argument checking.

How to use?

Protect arguments

About @protectron

• awaits a callable object (__call__ method)
  • return the event on success
  • raises SchemaValidationException on failure

Using your own schema validators

from ratatoskr import protectron, exceptions

def is_int(event):
    for k, v in event.iteritems():
        if not isinstance(v, int):
            raise exceptions.SchemaValidationError
    return event

@protectron(is_int)
def multiply_by_two(num):
    return num * 2

multiply_by_two(42)   # returns 84
multiply_by_two("42") # raises SchemaValudationError

Using voluptuous

from ratatoskr import protectron
from voluptuous import Schema

@protectron(Schema({
    'num': int
}))
def multiply_by_two(num):
    return num * 2


@protectron(Schema({
    'a': int,
    'b': int
}))
def multiply(a, b):
    return a * b


def validate_email(email):
    # ... code to validate email comes here ...


@protectron(Schema({
    'email': validate_email,
}))
def send_email(email):
    # ... code to send email comes here ...


multiply_by_two(42)     # returns 84
multiply_by_two("42")   # raises SchemaValudationError
multiply(2, 21)         # returns 42

send_email("no-reply@example.org") # OK
send_email("example.org") # raises SchemaValudationError

Dispatch event

Managing database table

from ratatoskr import dispatch_event, register_operation

@register_operation
def insert(item):
    # ... code to insert to db ...

@register_operation
def remove(item):
    # ... code to remove from db ...

def handler(event, context):
    return dispatch_event(event)

Assuming the following event, lambda will insert the item to the db.

event = {
    "operation": "insert",
    "args": {
        "item": {
            "username": "batman",
            "password": "s3cR3tPaZzW0rD"
        }
    }
 }

Installation

The package has not been deployed to pip yet. You can install it by:

• cloning the repository/or downloading release tarball and run pip install .
• OR run pip install ratatoskr

Tests

Writing tests is good! They protect you from doing things you don't want... It's not different at ratatoskr. Tests are written using pytest and run via tox. tox also checks for style using flake8 and does code coverage report using coverage.

• Run tox command in the root directory of the project to run all the tests.
• You can specify which interpreters should be used by tox -e [pyX.X]
• Read more about tox

PR's for testing new cases is always welcome!

Contribute

• Fork the repository on GitHub.

• Write a test which shows that the bug was fixed or that the feature works as expected.

  • Use tox command to run all the tests in all locally available python version.

• Install pre-commit via pip install pre-commit then pre-commit install.

• Send a pull request and bug the maintainer until it gets merged and published. :).

For more instructions see TESTING.rst.

MIT License

Copyright (c) 2016 Gergő Nagy

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.