AWS Lambda

AWS Lambda is a compute service that lets you run code without provisioning or managing servers. AWS Lambda executes your code only when needed and scales automatically, from a few requests per day to thousands per second. You pay only for the compute time you consume - there is no charge when your code is not running.

COU language preference for coding a Lambda is Python, Node or Go (in this order).

2. Reference

11. ZIP for AWS Lambda Python (Setuptools)

11.1. Reference (ZIP Setuptools)

lambda-setuptools

https://github.com/QuiNovas/lambda-setuptools

python-lambda-setuptools

Sample using 'lambda-setuptools' with Makefile, Pipenv, Pipfile and Terraform template

https://github.com/dnvriend/python-lambda-setuptools

11.2. Sample (ZIP Setuptools)

Sample project tree:

.

├── Makefile

├── Pipfile

├── README.md

├── setup.cfg

├── setup.py

└── src

├── app_util

│ ├── Exc.py

│ └── generic.py

└── lambda_function.py

Note: This sample lambda has the AWS Lambda default handler "lambda_function.lambda_handler".

Setuptools complains that file 'lambda_function.py' is at the root level instead of inside a package.

Although this is the default, the handler can be changed accordingly (see terraform template sample below).

Makefile:

.PHONY: pipenvini pipenvend clean package

# CONFIG

lambda_name=myapp_calendar

help:

@grep -E '^[a-zA-Z_-]+:.*?## .*$$' $(MAKEFILE_LIST) | awk 'BEGIN {FS = ":.*?## "}; {printf "\033[36m%-30s\033[0m %s\n", $$1, $$2}'

pipenvini: ## creates a new python environment with all dependencies (Pipfile)

pipenv install --dev

pipenvend: ## remove the python environment

pipenv --rm

clean: ## removes all build artifacts

rm -rf build dist .eggs

package: ## create a lambda distribution

pipenv run python setup.py ldist

#zip_filename, eg: dist/myapp_calendar-0.1.2.zip

lambdaupdate:

aws lambda update-function-code --function-name $(lambda_name) \

--zip-file fileb://$(shell ls dist/*.zip) > /dev/null

deploy: ## Clean, create artifact and update function code

make clean

make package

make lambdaupdate

Pipfile:

[[source]]

url = "https://pypi.python.org/simple"

verify_ssl = true

name = "pypi"

[packages]

requests = "*"

[dev-packages]

boto3 = "*"

setuptools = "*"

pytest = "*"

mypy = "*"

yapf = "*"

pylint = "*"

[requires]

python_version = "3.8"

setup.py:

#!/usr/bin/python3.8

from setuptools import setup

setup(

#name in the form of "namespace.mypackage"

name='myapp_calendar',

version='0.1.2',

author='thatsme',

author_email='thatsme@cou.edu',

description="AWS Lambda",

license='Apache 2.0',

package_dir={"": "src"},

#package blank needed if the handler is not the Setuptools generated one

packages=['', 'app_util'],

#set of dependencies

install_requires=['pyjwt', 'pytz', 'requests'],

setup_requires=['lambda_setuptools==0.4.4'],

#lambda_function in the form of 'my_package.some_module:some_function'

lambda_function='lambda_function:lambda_handler'

)

src/lambda_function.py:

# myapp_calendar lambda using runtime Python 3.8 #

######################################################

import app_util.Exc

from app_util.generic import ag_iso_datetime

from app_util.generic import ag_log_exception

from datetime import datetime

import json

import logging

import os

from pytz import timezone

# Logger

logger = logging.getLogger()

logger.setLevel(logging.INFO)

"""Lambda entry point

:param event: -

:param context: -

:returns: event

"""

def lambda_handler(event, context):

ret = {}

try:

print('Hello')

winter = "2021-02-27"

summer = "2027-08-31"

mytime = "18:27:59"

print('B')

print("a) "+ag_iso_datetime(winter, mytime))

print("b) "+ag_iso_datetime(summer, mytime))

print('C')

raise app_exc.AppRestExc(203, '{valid: false}')

#raise app_exception.AppRestExc(201, '{valid: true}')

print('D')

except Exception as e:

ag_log_exception('EXC MAIN_TRY_CATCH', e)

finally:

# Return

return ret

Terraform sample demostrating a Lambda handler inside a package:

Note: "myapp_calendar_function.handler" is automatically generated by Setuptools and points to the desired handler.

resource "aws_lambda_function" "test_lambda" {

function_name = "myapp_calendar"

filename = "dist/myapp_calendar-0.1.2.zip"

role = "${aws_iam_role.role_for_lambda.arn}"

handler = "myapp_calendar_function.handler"

source_code_hash = "${base64sha256(file("dist/myapp_calendar-0.1.2.zip"))}"

runtime = "python3.8"

}

12. ZIP for AWS Lambda Python (Bash script)

Given the following layout of the project:

.├── lambda_function.py├── README.md├── requirements.txt├── runZip.sh└── setup.cfg

where lambda_function.py is the lambda function.

setup.cfg

[install]

prefix=

requirements.txt

xlrd

runZip.sh

#!/bin/bash

tech_comp=myapp_collaboration

lambda_name=collaboration-myapp-test

echo == Cleaning up

rm -rf package/

rm $tech_comp.zip

echo

echo == Installing dependencies

pip install --requirement requirements.txt --target ./package

echo

echo == Creating zip archive with dependencies

cd package

zip -r9 ../$tech_comp.zip ./ -x "bin/*"

cd ..

echo

echo == Add function code to the archive

zip -g ./$tech_comp.zip lambda_function.py

echo

echo == Update code of lambda function

aws lambda update-function-code \

--function-name $lambda_name \

--zip-file fileb://$tech_comp.zip > /dev/null

echo

20. AWS Lambda Node.js

Eg: COU app 'ulises'.

30. AWS Lambda Go

This Lambda using Go language example sets up 'No more index.html mess with AWS CloudFront/S3' found at:

https://github.com/artyom/cloudfront-autoindex

30.1. Install Go 1.15

$ lsb_release -irs

Ubuntu

20.04

https://github.com/golang/go/wiki/Ubuntu

sudo add-apt-repository ppa:longsleep/golang-backports

sudo apt update

sudo apt install golang-go

Note that golang-go installs latest Go as default Go. If you do not want that, install golang-1.15 instead and use the binaries from /usr/lib/go-1.15/bin.

Verify installation

$ go version

go version go1.15.7 linux/amd64

30.2. Build and create lambda .zip

git clone https://github.com/artyom/cloudfront-autoindex.git

cd cloudfront-autoindex/

Build:

GOOS=linux GOARCH=amd64 go build -o main

Compress:

zip -9 lambda.zip main

30.3. Create AWS Lambda

Create a new AWS Lambda:

Function name: cloudfrontautoindex-myapp-dev

Runtime: Go 1.x

(*)Use an existing role: role-lambda-s3-validaciotp-dev

Tab Code:

Upload from .zip file: lambda.zip

Handler: main (binary name built above)

Tab Configuration:

Department=manual

ci=myapp

30.4. Configure S3 event notification

S3 bucket: front-s3-myapp-dev

Tab Properties:

Event notifications > Create event notification

Event name: cloudfrontautoindex-event

Suffix: index.html

Event types: All object create events (except 's3:ObjectCreated:Copy')

Destination > Lambda function: cloudfrontautoindex-myapp-dev (created above)

40. Lambda error handling

40.1. Configuring destinations for asynchronous invocation

You can configure separate destinations for events that fail processing and events that are successfully processed.

Serverless example:

resources:

DeadLetterQueue:

Type: "AWS::SQS::Queue"

Properties:

QueueName: sqs-queue-${opt:stage, self:provider.stage}-dlq

functions:

DLQFunction: # function that moves the S3 file

handler: handlers.dlq

events:

- sqs:

arn:

Fn::GetAtt:

- DeadLetterQueue

- Arn

sendEmail:

handler: handlers.email

destinations: #onfailure supports different options, among them the arn of a SQS

onFailure: ${self:custom.queue-arn} #doesn't seem to admit "Fn::GetAtt:"

events:

- s3:

bucket: myS3storage

event: s3:ObjectCreated:*

rules:

- prefix: transit/noseque

70. Boto3 (AWS SDK for Python)

Python API for AWS infrastructure services. See https://docs.aws.amazon.com/pythonsdk/

For the S3 client, see https://boto3.amazonaws.com/v1/documentation/api/latest/reference/services/s3.html

It can be used as a client or as a resource.

Using it as a client is preferred, since as a resource makes IDEs unable to check types and autodiscover methods.

Example getting an object from a bucket using the key:

s3 = boto3.client('s3')

obj = s3.get_object(

Bucket=object_bucket_name,

Key=object_key,

)