Infrastructure as Code: An introduction

Infrastructure as Code (IaC) is an approach to managing and provisioning computing infrastructure through machine-readable configuration files rather than manual processes. IaC eliminates configuration drift, enables version control for infrastructure, and makes environments reproducible. It has become a foundational practice in DevOps and cloud-native development.

IaC as a concept

At its core, IaC is about managing infrastructure in the same way that software teams manage application code. You write definitions for your infrastructure in a domain-specific language (DSL), and then run tools that use these definitions to provision resources. This could be anything from a simple server to an entire data center.

The fundamental benefit of IaC is consistency. It eliminates the "it works on my machine" problem because every environment is created from the same blueprint. This approach also supports DevOps practices such as continuous integration (CI), continuous delivery (CD), and site reliability engineering (SRE).

Benefits of Infrastructure as Code

Speed and Simplicity: IaC tools can quickly set up complex environments for various stages (development, staging, production) and keep them in sync.
Version Control: Like application code, infrastructure code can be versioned. This allows you to track changes, roll back to previous versions, and create test cases for infrastructure.
Reduced Errors: By eliminating manual configuration, IaC reduces the potential for human error. Consistency across environments also helps to catch issues early.
Scalability: IaC makes it easier to replicate infrastructure setup for different environments or new projects, promoting scalable operations.

Drawbacks of Infrastructure as Code

Learning Curve: IaC tools often have their own DSLs, which require time and effort to learn. There is also the complexity of understanding cloud provider services.
Maintaining Infrastructure Code: Infrastructure code has to be maintained just like application code. It needs regular refactoring, testing, and updates, which can be time-consuming.
Debugging: Debugging infrastructure setup can be complex, especially when there are many interdependencies.

IaC Tools in Practice

Terraform: An open-source tool created by HashiCorp, Terraform is platform-agnostic and can manage a wide array of service providers with its plugin system. However, its configuration language, HCL, can be complex to learn and manage. Another consideration is that managing different environments with Terraform often means duplicating configuration code, which can lead to inconsistencies.
Pulumi: Unlike Terraform, Pulumi allows you to define your infrastructure in general-purpose programming languages like Python, JavaScript, and Go. This makes the learning curve less steep for developers. However, as Pulumi directly interacts with the cloud provider's API, any changes to the API could potentially break your infrastructure code.

These tools make a big difference in managing infrastructure, but they still come with complexities and challenges. It's important to have a deep understanding of these tools and the cloud resources you are dealing with. Infrastructure as Code isn't just a fancy way of setting up servers; it's a fundamental practice that, when properly implemented, can improve the efficiency and reliability of your operations.

Infrastructure from Code: The Next Evolution

While traditional IaC tools like Terraform and Pulumi require you to maintain separate configuration files, a newer approach called Infrastructure from Code infers infrastructure requirements directly from application code.

Encore pioneered this approach for backend development. Instead of writing Terraform configurations, you declare infrastructure using type-safe primitives in your application code:

import { SQLDatabase } from "encore.dev/storage/sqldb";
import { Topic } from "encore.dev/pubsub";
import { CronJob } from "encore.dev/cron";

// Database is automatically provisioned
const db = new SQLDatabase("users", {
  migrations: "./migrations",
});

// Pub/Sub topic with automatic cloud provisioning
const signups = new Topic<SignupEvent>("signups", {
  deliveryGuarantee: "at-least-once",
});

// Cron job runs automatically
new CronJob("cleanup", {
  title: "Clean up old sessions",
  schedule: "0 2 * * *",
  endpoint: cleanupSessions,
});

Encore parses this code and automatically provisions the appropriate infrastructure:

Locally: PostgreSQL in Docker, NSQ for Pub/Sub
AWS: RDS, SNS/SQS, CloudWatch Events
GCP: Cloud SQL, GCP Pub/Sub, Cloud Scheduler

This eliminates the learning curve of HCL or YAML, keeps infrastructure and application code in sync, and removes the need for separate DevOps expertise. For teams comparing approaches, see:

Infrastructure as Code: An Introduction

What is IaC and when is it appropriate?