12 Cloud Commandments: Applying 12 Factor App Principles to Master Terraform — Part 1

Remember the days when deploying a new app meant wrestling with servers, deciphering cryptic configuration files, and hoping you didn’t trigger a rogue hamster on the wheel powering your infrastructure? Those days, thankfully, are fading faster than a Snapchat filter. Modern Cloud architecture and DevOps practices have evolved into a sleek, efficient dance between code and infrastructure. We’re talking automation, standardization, and a whole lot less server-induced sweat.

But amidst this technological tango, one set of principles still shines brightly: the 12 Factor App. These timeless guidelines, born in the early days of the Cloud, remain as relevant as ever. They’re like the secret sauce that keeps your applications scalable, reliable and deployable with the click of a button.

So, buckle up, because, in this blog post, we’re about to do something pretty cool: we’re going to marry the power of Terraform, an open-source Infrastructure as Code (IaC) tool, with the wisdom of the 12 Factor App principles. Think of it as a match made in DevOps heaven. We’ll show you how each principle can be applied within the context of Terraform, creating an infrastructure that’s as nimble and adaptable as your code itself.

12 Factor App Principles

The twelve-factor app is a methodology for building software-as-a-service apps that are designed to be:

• Scalable
• Maintainable
• Portable

The principles guide developers in designing Cloud-native applications, focusing on codebases, dependencies, configuration and processes, ensuring productivity, dynamic scaling and resilience, and promoting a consistent approach to modern Cloud platforms.

Some key aspects of the twelve-factor methodology include:

• Strict separation of config from code
• Ability to scale out via the process model
• Loose coupling between app components
• Designing stateless processes
• Ease of deploying/rolling back versions
• Minimizing divergence between development, staging, production
• Easy portability between execution environments

We will now examine the amalgamation of two potent techniques in this blog post: Terraform, an open-source Infrastructure as Code (IaC) tool, and the “12 Factor App” principles. This union provides a significant synergy that enables us to create robust repeatable infrastructure at scale.

So, let’s get started, shall we?

Codebase — One Codebase Tracked in Revision Control, Many Deploys

Think of your codebase as the ultimate recipe for your Cloud infrastructure. Just like a well-loved cookbook, it should be organized, easy-to-follow, and free of spaghetti code. When everyone’s on the same page and singing from the same hymn sheet, you’ll avoid the chaos of mismatched ingredients and cooking disasters. Keep it tidy, folks — no one likes a messy kitchen!

Scenario 1: The “Spaghetti Stack” Dilemma

Picture this: you inherit a project from a colleague who left the company to pursue their dream. As you dive into the codebase, you realize it’s more tangled than a plate of spaghetti at an Italian wedding. Modules, functions, and configurations are all mixed-up, making it impossible to decipher what does what. This spaghetti stack not only confuses you, but also increases the risk of introducing bugs or making unintended changes. It’s like trying to find a needle in a haystack, except that the haystack is made of needles.

Scenario 2: The “Version Control Vortex”

Ever experienced the frustration of trying to track changes in a project where everyone seems to have their own version of reality? It’s like playing a game of “Chinese Whispers” but with code. One engineer adds a new feature in their local environment, another tweaks a configuration file on the server directly, and chaos ensues. Before you know it, you’re knee-deep in merge conflicts, lost commits and version control mayhem. It’s a nightmare for collaboration, and leads to more headaches than a hangover on a Monday morning.

Scenario 3: Terraform Configuration Monolith

A new DevOps team managing a sprawling AWS infrastructure encounters a monolithic configuration file in the Terraform codebase. This file consists of every aspect of the infrastructure, from networking to compute instances, making it intimidating and introducing risks. A simple typo could lead to critical services downtime, and understanding the impact of changes becomes a difficult task. For example, updating security group rules for a specific service can be a “Where’s Waldo” game, increasing the likelihood of human error and downtime.

The 12-Factor App principle of “Codebase” comes to the rescue. Treat your Terraform code like the precious Infrastructure as Code (IaC) it is. Store it in a central repository like Git, the knight in shining armor of version control. This allows for easy collaboration, disaster recovery, and a sigh of relief knowing you can revert to a working version, if needed.

In conclusion, embracing the “Codebase” principle of the 12 Factor App not only promotes clarity and manageability, but also mitigates risks inherent in sprawling infrastructure configurations. By modularizing Terraform code into discrete components, teams can effectively tackle complexity, reducing the likelihood of human error and downtime. A monolithic configuration file transforms into a navigable landscape, where updates are precise, and impact assessments are straightforward. With this approach, managing AWS infrastructure becomes less of a daunting task and more of a streamlined operation, empowering DevOps teams to wield Terraform with confidence and efficiency.

Dependencies — Explicitly declare and isolate dependencies

They are like the ingredients in your favorite dish — you need them to make the magic happen, but too many can spoil the broth. Keep a close eye on what you’re adding to the pot, and make sure each ingredient pulls its weight. After all, no one wants a soufflé that collapses under the weight of too many eggs!

Scenario 1: The “Dependency Domino Effect”
You’re happily coding away, when suddenly a wild dependency appears! You install it without a second thought, only to realize it brings along its own entourage of dependencies. Before you know it, your project has more dependencies than a family reunion. Each update becomes a game of Russian roulette, as you pray that one tiny change doesn’t send the entire stack tumbling down like a house of cards. It’s dependency management, but with all the stress of a high-stakes poker game.

Scenario 2: The “Versioning Volcano”
Picture this: you’re tasked with updating a library in your project to fix a critical security vulnerability. Easy, right? Wrong. Turns out, that library is a critical piece of the puzzle, used in multiple modules across your application. You update it in one place, only to realize that it breaks compatibility with another module that’s still using an older version. Now you’re stuck in a versioning volcano, trying to balance stability with security while dodging eruptions left and right. It’s a precarious game of “Jenga,” where one wrong move could bring the whole tower crashing down.

Scenario 3: Uncontrolled Module Dependencies

In the world of Cloud and DevOps, managing dependencies in Terraform modules is crucial for maintaining a scalable and efficient Infrastructure as Code (IaC) setup. Consider a scenario where you have a main Terraform module that provisions AWS resources such as EC2 instances and RDS databases, and it relies on a separate module for managing security groups. Now, imagine that the security group module is updated frequently with new features or fixes. Without careful versioning and dependency management, these updates could unintentionally break the main module, leading to deployment failures or security vulnerabilities.

To illustrate, let’s say you have a Terraform configuration like this:

module "main" {
source = "./main_module"
// other configurations
security_group_id = module.security_group.id
}
module "security_group" {
source = "./security_group_module"
// other configurations
}

In this example, the main module depends on the security group module. However, if the security group module undergoes significant changes without proper versioning or testing, it could introduce unexpected behavior or errors in the main module, disrupting the infrastructure deployment process.

In the ever-evolving landscape of Cloud and DevOps, mastering dependency management in Terraform is non-negotiable. Picture this: your main Terraform module orchestrating vital AWS resources is only as robust as its supporting modules, like those handling security groups. Yet, without diligent versioning and dependency control, each update to these ancillary modules becomes a high-stakes gamble, risking deployment hiccups or worse, security breaches. Embracing the 12 Factor App principle of Dependencies isn’t just about ticking boxes; it’s about safeguarding your infrastructure’s integrity and agility. So, let’s commit to meticulous dependency management, ensuring our Terraform setups scale reliably in the face of constant change.

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