recipes.rst

Recipes and other decorators for lambda handlers

PostgreSQL db client

Here is a sample decorator I wrote for a little side project that connects to a PostgreSQL database and add the connection to the context object:

import os

import boto3
import records
from lambda_decorators import LambdaDecorator


class database(LambdaDecorator):
    def before(self, event, context):
        self.db = records.Database(boto3.client('ssm').get_parameter(
            Name='db_url', WithDecryption=True)['Parameter']['Value'])
        context.db = self.db

        return event, context

    def after(self, response):
        self.db.close()
        return response

    def on_exception(self, exception):
        if hasattr(self, 'db'):
            self.db.close()
        raise exception

Then, when defining your handler:

from database import database

@database
def handler(event, context):
    context.db.query('select 1')
    return {}

Raven/Sentry configuration

See raven-python-lambda for an example of a library for aws lambda that also uses a decorator to configure logging to use Raven/Sentry.