# Run this Lambda function inside a VPC with a MongoDB instance inside it.
# Set up security groups to allow the function to communicate with the MongoDB endpoint
# NAT service or NAT instance is required because the function need to access AWS KMS, which an external endpoint
# Set four environment variables for the function containing the details required for the MongoDB endpoint uri
# I used the Bitnami MongoDB install from the AWS Marketplace

import boto3
import os

from base64 import b64decode
from pymongo import MongoClient

print "decrypting enviroment variables"
ENCRYPTEDusername = os.environ['MongoDBusername']
MongoDBusername = boto3.client('kms').decrypt(CiphertextBlob=b64decode(ENCRYPTEDusername))['Plaintext']
ENCRYPTEDpassword = os.environ['MongoDBpassword']
MongoDBpassword = boto3.client('kms').decrypt(CiphertextBlob=b64decode(ENCRYPTEDpassword))['Plaintext']
ENCRYPTEDaddress = os.environ['MongoDBaddress']
MongoDBaddress = boto3.client('kms').decrypt(CiphertextBlob=b64decode(ENCRYPTEDaddress))['Plaintext']
ENCRYPTEDname = os.environ['MongoDBname']
MongoDBname = boto3.client('kms').decrypt(CiphertextBlob=b64decode(ENCRYPTEDname))['Plaintext']


def lambda_handler(event, context):
    print "starting function"
    print "constructing uri for MongoDB connection"
    uri = "mongodb://" + MongoDBusername + ":" + MongoDBpassword + "@" + MongoDBaddress + "/" + MongoDBname
    client = MongoClient(uri)
    print client
    db = client['lambda_demo']
    print db
    result = db.lambda_demo.insert_one(event)
    print result
    print "function end"