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msk-framework-terraform

Purpose

This repository hosts a terraform module which performs the following tasks (when invoked as a child module):

  1. Creates of a base network environment in AWS, consisting of:
  • 1 VPC, with a configurable CIDR Range, for example 10.0.0.0/16
  • 4 Subnets, distributed evenly across 3 Availability zones, with the following (example) CIDR Ranges:
    • 10.0.1.0/24 [Private]
    • 10.0.2.0/24 [Private]
    • 10.0.3.0/24 [Private]
    • 10.0.10.0/24 [Public]
  • An Internet Gateway
  • A NAT Gateway
  • Routes, Route Tables & Associations

  1. Installs an MSK (Kafka) Cluster on AWS

  2. Installs 2 EC2 instances:

  • An msk-client EC2 instance, which has the following things pre-installed (via a user-data script):
    • The kafka client application and libraries
    • A script called, create-topic.sh which creates a topic on the MSK (kafka) cluster
    • A client.properties file
  • A bastion EC2 instance, which can be used as a 'jump server' to connect from the internet to the msk-client EC2 instance (which resides in a private subnet)
  1. Creates the necessary IAM roles & policies

Prerequisites

Terraform and AWS CLI configuration

In order to use this module, terraform needs to be properly installed and configured. Whilst this is out of the scope of this README file, an example provider.tf file is shown below. The official terraform documentation explains how to get terraform up and running on a local machine. Alternatively, Terraform Cloud is another option.

Create a provider.tf file

//Configure the terraform backend (S3) and aws provider
terraform {
  backend "s3" {
    bucket  = "<s3-bucketname goes here>"
    key     = "terraform.tfstate"
    region  = "us-east-1"
  }

  required_providers {
    aws = {
      source = "hashicorp/aws"
    }
  }
}

//Specify which AWS region and profile should be used by default
provider "aws" {
  region  = "us-east-1"
}

Configure an SSH Key

Create an SSH Keypair

Create a new ssh-key for use with this environment, using the ssh-keygen command:

ssh-keygen -N "" -f my-new-ssh-key

The private key should never be shared, and its file location should be the value for private_key_path in the main.tf file example shown below. The contents of the public key should be given as the value for public_key_path

Ensure the correct permissions on the new keypair

chmod 400 my-new-ssh-key
chmod 644 my-new-ssh-key.pub

Ensure ssh-agent is running

eval $(ssh-agent)

Add your new key to the ssh-agent

ssh-add my-new-ssh-key

Check that your new key has been loaded into the ssh-agent

ssh-add -l

Usage

The terraform code hosted in this repository can be easily used by creating a parent module on your local machine, in a main.tf file as shown below. (More information about terraform modules can be found on this page)

Note the source parameter can be used to either point directly to this repository or a local copy of the terraform module.

Create a main.tf file

#main.tf file for deploying msk-framework-terraform
module "msk-framework-environment" {
  source         = "github.com/edrandall-dev/msk-framework-terraform"
  //source       = "../msk-framework-terraform"

  public_key_value = "ssh-rsa AAAAB3NzaC1A.....b+oTz7tb0WF2aiOPp0="
  private_key_path = "~/.ssh/my-ssh-key"
  bastion_instance_type = "t3.micro"
  vpc_base_cidr = "10.0.0.0/16"
  ssh_source_cidr   = "0.0.0.0/0"
  env_prefix = "msk-tf-cloud"
  target_region = "us-east-1"
}

output "bastion_ssh_command" {
  value = module.msk-framework-environment.bastion_ssh_command
}

output "msk_test_ssh_command" {
  value = module.msk-framework-environment.msk_test_ssh_command
}

Validate Terraform Code

Once the main.tf file has been properly created, the terraform configuration can be validated:

terraform validate

Deploy Resources (plan & deploy)

terraform plan

terraform apply -auto-approve

Connecting to the bastion

Once the terraform apply has completed. The bastion can be connected to by using the first command which is shown as part of the terraform output. For example:

ssh -A -o StrictHostKeyChecking=no ec2-user@12.34.56.78

Once connected to the bastion instance, a further connection can be made (from the bastion instance) onto the msk-test instance which resides in the first private subnet (and only has a private IP address). This can be done with the second command which is shown as part of the terraform output. For example:

ssh -A -o StrictHostKeyChecking=no ec2-user@10.0.11.22

Running the create-topic.sh script

The create-topic.sh script resides in the ec2-users home directory, in a subdirectory called kafka (along with the other client tools). The script is pre-populated with the correct broker endpoints. If run without arguments, it will create a topic on the MSK (Kafka) cluster called my-topic. However, it can also be run with a single argument to specify a topic name other than "my-topic", for example:

#creates a topic called my-topic
./create-topic.sh

#creates a topic called your-topic
./create-topic.sh your-topic

AWS Resources

  • Users are reminded that the deployment of cloud resources will incur costs.
  • The creation of MSK (kafka) clusters takes a long time. The installation process will likely take upwards of 25 minutes.

If you tear down the environment and start again, you may need to delete and re-add your ssh-key into the ssh-agent. The command ssh-add -D can be used to delete all entries from ssh-agent.