AWS ALB (Application Load Balancer)

An abstract application loadbalancer construct. It creates a loadbalancer and default security groups and listeners for the loadbalancer. Also, this loadbalancer is ready for blue-green deployments.

Remarks

The project is written by Laimonas Sutkus and is owned by iDenfy. This is an open source library intended to be used by anyone. iDenfy aims to share its knowledge and educate market for better and more secure IT infrastructure.

Related technology

This project utilizes the following technology:

• AWS (Amazon Web Services).
• AWS CDK (Amazon Web Services Cloud Development Kit).
• AWS CloudFormation.
• AWS Loadbalancer.
• AWS Security groups.

Assumptions

This library project assumes the following:

• You have knowledge in AWS (Amazon Web Services).
• You have knowledge in AWS CloudFormation and AWS loadbalancing.
• You are managing your infrastructure with AWS CDK.
• You are writing AWS CDK templates with a python language.

Install

The project is built and uploaded to PyPi. Install it by using pip.

pip install aws-alb

Or directly install it through source.

./build.sh -ic

Description

It is usually hard to create a loadbalancer following best practices and rules. Also, most of the time the deployed loadbalancer will lack some configuration functionality for deployment management. We tackle these problems by providing you a library to easily deploy and maintain a loadbalancer with right security groups, right listeners and most importantly right configuration for blue-green deployments.

Examples

To create an application loadbalancer create an ApplicationLoadbalancer instance in your stack. An example is given below:

from aws_cdk import core, aws_ec2
from aws_alb.application_loadbalancer import ApplicationLoadbalancer

class MainStack(core.Stack):
    def __init__(self, scope: core.App) -> None:
        super().__init__(
            scope=scope,
            id='MyCoolStack'
        )
        
        # Create your own vpc.
        self.vpc = aws_ec2.Vpc(
            self,
            'MyCoolVpc'
        )

        self.public_http_loadbalancer = ApplicationLoadbalancer(
            scope=self,
            prefix='MyCool',
            vpc=self.vpc,
            loadbalancer_subnets=self.vpc.public_subnets,
            security_groups=None,
        )

To create listeners and target groups that are blue-green deployments ready:

from aws_alb.params.listener_params import ListenerParams
from aws_alb.params.target_group_params import TargetGroupParams
from aws_alb.application_loadbalancer import ApplicationLoadbalancer
from aws_cdk.aws_ec2 import Vpc

loadbalancer = ApplicationLoadbalancer(...)
vpc = Vpc(...)

blue, green = loadbalancer.listeners.create_blue_green(
    blue_listener_params=ListenerParams(
        prefix='MyCool',
        loadbalancer=loadbalancer,
        port=80
    ),
    green_listener_params=ListenerParams(
        prefix='MyCool',
        loadbalancer=loadbalancer.loadbalancer,
        port=8000
    ),
    blue_target_group_params=TargetGroupParams(
        prefix='MyCool',
        vpc=vpc,
    ),
    green_target_group_params=TargetGroupParams(
        prefix='MyCool',
        vpc=vpc,
    )
)

# If you need, you can access created target groups and listeners.
blue_target_group, blue_listener = blue
green_target_group, green_listener = green

# To see to which ports listeners are listening to:
print(blue_listener.port)
print(green_listener.port)

Usually, it is the best practice to have one loadbalancer with two (http and https) listeners and have listener rules to route traffic. To create default listeners:

from aws_alb.application_loadbalancer import ApplicationLoadbalancer
from aws_cdk.aws_certificatemanager import CfnCertificate
from aws_cdk.aws_ec2 import Vpc

loadbalancer = ApplicationLoadbalancer(...)
vpc = Vpc(...)
cert = CfnCertificate(...)

blue, green = loadbalancer.listeners.create_default_listeners(
    prefix='MyCool',
    loadbalancer=loadbalancer.loadbalancer,
    certificate=cert
)

print(blue.port) # Should be 443.
print(green.port) # Should be 44300.