CDK Python - Kubernetes The (real) Hard Way on AWS!

This little project creates the infrastructure in CDK Python for my blog post Kubernetes The (real) Hard Way on AWS.

Terraform code available 🔗HERE

You can practice creating a multi node K8s Cluster yourself for training purposes or CKA exam preparation.

Requirements

• Existing AWS EC2 Key Pair
• Existing AWS Route53 Public Hosted Zone
• aws-cli Profile
• AWS CDK (npm install -g cdk)
• Python3

Features

Default values - you can adapt all of them to your needs

• AWS CDK Python
• 1x VPC, 3x Public Subnets, 3x Private Subnets, Route Tables, Routes
• 3x Worker Nodes
• 3x Master Nodes
• 3x Etcd Nodes
• 1x Bastion Host
• Route53 Records for internal & external IPv4 addresses
• 1x Public LoadBalancer for Master Nodes (external kubectl access)
• 1x Private LoadBalancer for Master Nodes (fronting kube-apiservers)
• 1x Public LoadBalancer for Bation Host (AutoScalingGroup)
• Gets most recent Ubuntu AMI for all regions (via Boto3)
• Install awscli, cfssl, cfssl_json via UserData
• Allows external access from workstation IPv4 address only (to Bastion & MasterPublicLB)

Variables

Name	Description	Type	Default
aws_account	AWS account ID to deploy infrastructure	string	''
aws_region	AWS region	string	'us-east-1'
bastion_desired_capacity	Bastion ASG desired nodes	int	1
bastion_instance_type	Bastion EC2 instance type	string	't3a.small'
bastion_min_capacity	Bastion ASG min. nodes	int	1
bastion_max_capacity	Bastion ASG max. nodes	int	1
etcd_desired_capacity	etcd ASG desired nodes	int	3
etcd_instance_type	etcd EC2 instance type	string	't3a.small'
etcd_min_capacity	etcd ASG min. nodes	int	3
etcd_max_capacity	etcd ASG max. nodes	int	3
master_desired_capacity	K8s-Master ASG desired nodes	int	3
master_instance_type	K8s-Master EC2 instance type	string	't3a.small'
master_min_capacity	K8s-Master ASG min. nodes	int	3
master_max_capacity	K8s-Master ASG max. nodes	int	3
worker_desired_capacity	K8s-Worker ASG desired nodes	int	3
worker_instance_type	K8s-Worker EC2 instance type	string	't3a.small'
worker_min_capacity	K8s-Worker ASG min. nodes	int	3
worker_max_capacity	K8s-Worker ASG max. nodes	int	3
ssh_key_pair	AWS EC2 Key Pair name	string	''
pod_cidr	Pod CIDR network first octets (for POD_CIDR envvar)	string	'10.200'
tag_owner	Owner Tag for all resources	string	'napo.io'
tag_project	Project Tag for all resources	string	'k8s-the-real-hard-way-aws'
vpc_cidr	AWS VPC network CIDR	string	'10.5.0.0/16'
zone_fqdn	AWS Route53 Hosted Zone name	string	''

CDK Python Tutorial

The cdk.json file tells the CDK Toolkit how to execute your app.

This project is set up like a standard Python project. The initialization process also creates a virtualenv within this project, stored under the .env directory. To create the virtualenv it assumes that there is a python3 (or python for Windows) executable in your path with access to the venv package. If for any reason the automatic creation of the virtualenv fails, you can create the virtualenv manually.

To manually create a virtualenv on MacOS and Linux:

$ python3 -m venv .env

After the init process completes and the virtualenv is created, you can use the following step to activate your virtualenv.

$ source .env/bin/activate

If you are a Windows platform, you would activate the virtualenv like this:

% .env\Scripts\activate.bat

Once the virtualenv is activated, you can install the required dependencies.

$ pip install -r requirements.txt

At this point you can now synthesize the CloudFormation template for this code.

$ cdk synth

To add additional dependencies, for example other CDK libraries, just add them to your setup.py file and rerun the pip install -r requirements.txt command.

Useful commands

• cdk ls list all stacks in the app
• cdk synth emits the synthesized CloudFormation template
• cdk deploy deploy this stack to your default AWS account/region
• cdk diff compare deployed stack with current state
• cdk docs open CDK documentation

Enjoy!