cloud-talk-cats-or-dogs

Demo Infrastructure as Code for Cloud Talk series

Overview

This project demonstrates Infrastructure as Code principles using Terraform and Salt. The Terraform modules will create and manage the following resources:

• IAM Instance Role
• S3 Bucket
• Application Load Balancer
• Security Groups (1 for the load balancer and 1 for EC2 instances)
• Autoscaling Group and Launch Config

Salt is used within the EC2 instances (deployed by the Autscaling Group) to install and configure an Apache web server. The web server will serve cat or dog images from the S3 bucket. One Availability Zone will be designated as the "cats AZ", and any EC2 instance running in that AZ will only serve cat images. Instances in any other AZ will serve only dog images. This is intended to help demonstrate the failover and recovery capabilities of the architecture.

Usage

1. Create a main.auto.tfvars file in the main module. See main/variables.tf for the required and optional variables. This file is ignored intentionally by source control so it is not committed to the project.

2. The first time the project is deployed, execute the following make targets in the listed order. For subsequent executions, execute the targets as needed depending on the changes being evaluated. See [Make Targets][#make-targets] for more info on the available targets.

   • make test
   • make apply/iam
   • make apply/bucket
   • make apply/main

Terraform Modules

All resources are deployed using Terraform. The project consists of 3 Terraform modules:

• iam
  • Manages the IAM Instance Role
• bucket
  • Manages the S3 bucket
• main
  • Manages all other resources, including the objects in the S3 bucket
  • Utilizes the lx-autoscale module from terraform-aws-watchmaker

NOTE: The iam and bucket modules must be deployed first, as their resources must exist when the main module is deployed.

Make Targets

There is a Makefile that helps manage the project workflow.. The following make targets are supported:

• make test
  • Runs terraform fmt to standardize format of all Terraform files.
  • Runs terraform validate on all modules to check for syntax errors.
• make <tf_command>/<module>
  • Executes the <tf_command> in the specified <module>. The command init supports an additional argument upgrade=<true|false (default)>, which controls whether to force terraform to re-download all providers and modules (see terraform init -help).
• make <tf_command>/all
  • Executes the <tf_command> in all Terraform modules. This target does not account for dependencies between modules, so should not be used for plan, apply, or destroy commands. init and validate are safe.