Create a Private Microservice Using an Application Load Balancer

hipchat_proxy.py

import json
import logging
import os

from lambdarest import lambda_handler
from slackclient import SlackClient

logger = logging.getLogger()
logger.setLevel(logging.INFO)

# ideally this should be replaced with a call to: secretsmanager.get_secret_value(SecretId=secret_name)
sc = SlackClient(os.environ['SLACK_TOKEN'])


def generic_handler(event, room_id_or_name):
    msg = event['body']
    hipchat_body = json.loads(msg)
    msg_text = hipchat_body['message']
    try:
        resp = sc.api_call("chat.postMessage", channel="test_room", text=msg_text)
        if resp['ok']:
            logger.info("Success calling slack")
            return {"statusCode": 204, "body": ""}
        else:
            logger.error("Slack response %s", resp)
            return {"statusCode": 500, "body": "Slack response: " + resp}

    except Exception as err:
        logger.error("Caught error calling slack", err)
        return {"statusCode": 500, "body": "" + err}


@lambda_handler.handle("post", path="/v2/<room_id_or_name>/notification")
def room_notification(event, room_id_or_name):
    return generic_handler(event, room_id_or_name)


# aws lambda needs to reference code in your project to behave, so redefine reference to handler
the_handler = lambda_handler

requirements.txt

# this file contains runtime dependencies (setup.py can used to create development/test dependencies)
requests
slackclient
python-lambdarest>=5.4.0

stack_build.sh

#!/bin/bash -xe

BASEDIR=$(cd "$(dirname "$0")/.."; pwd)
echo "project directory $BASEDIR"

: ${TARGET_DIR:=${BASEDIR}/tmp}

rm -rf ${TARGET_DIR}
mkdir -p ${TARGET_DIR}

# arg 1 - space separated paths to check
# arg 2 - friendly name for error messages
function findFile() {
    for x in $1; do
        if [[ -f ${x} ]]; then
            echo ${x}
            return
        fi
    done
    >&2 echo "Could not find $2 to use"
    exit 1
}

# modify this accordingly depending on the name and whether python3.6 (or python3.7 if that's your runtime) is on the path
# here i pull in python 3.6 installed from centos-release-scl-rh
PYTHON=$(findFile "$(which python3.6) /opt/rh/rh-python36/root/usr/bin/python $(which python3)" "python3.6")
PIP=$(findFile "$(which pip3.6) /opt/rh/rh-python36/root/usr/bin/pip3.6 $(which pip3)" "pip3.6")
# newer python doesn't use the virtualenv script, instead uses "python -m venv"
VIRTUALENV="$PYTHON -m venv"

# barfs if aws-sam-cli is installed in venv due to dependencies, so install at user level first
${PIP} install --user aws-sam-cli
export PATH=$(${PYTHON} -m site --user-base)/bin:$PATH

echo "Activating virtualenv"
${VIRTUALENV} venv

if [[ -f venv/bin/activate ]]; then
    source venv/bin/activate
else
    source venv/Scripts/activate
fi

# update pip and wheel
pip install -U pip wheel

####################################################
# TODO TESTS
# create a setup.py with test dependencies then use:
####################################################
#pip install .[tests]
#py.test

pwd
mkdir -p .aws-sam/build

sam build --debug

if [[ -z "${BUCKET}" ]] || [[ -z "${PREFIX}" ]]; then
  >&2 echo "Skipping package and upload step as BUCKET or PREFIX is not set"
  exit 1
fi

cd .aws-sam/build

aws cloudformation package \
    --template-file template.yaml \
    --output-template-file ${TARGET_DIR}/serverless-output.yaml \
    --s3-bucket ${BUCKET} \
    --s3-prefix ${PREFIX}

echo "to deploy run: (replacing YOUR_SLACK_TOKEN with your token)"
echo "aws cloudformation deploy \
 --template-file ${TARGET_DIR}/serverless-output.yaml \
 --stack-name hipchat-proxy \
 --parameter-overrides \
    SlackToken=YOUR_SLACK_TOKEN \
    EnvName=${ENV_NAME}"

template.yaml

AWSTemplateFormatVersion: '2010-09-09'
Transform: AWS::Serverless-2016-10-31

Parameters:
  SlackToken:
    Type: String
    Description: "the token used to call slack"

Resources:
  HipchatFunction:
    Type: AWS::Serverless::Function
    Properties:
      Handler: hipchat_proxy.the_handler
      Runtime: python3.6
      CodeUri: ./
      Description: "A simple hipchat to slack convertor"
      Timeout: 5
      Environment:
        Variables:
          SLACK_TOKEN: !Ref SlackToken

https://github.com/trustpilot/python-lambdarest
has been updated to support Application Load Balancer:

from lambdarest import create_lambda_handler

lambda_handler = create_lambda_handler(application_load_balancer=True)

@lambda_handler.handle("get", path="/foo//")
def my_own_get(event, id):
return {"my-id": id}

pip install lambdarest>=5.4.0