Pulumi vs Terraform: Evolution of Infrastructure as Code

As a Senior Platform Engineer who has spent countless hours wrangling cloud infrastructure across GCP and Azure, I've had a front-row seat to the evolution of Infrastructure as Code (IaC). My journey began firmly in the Terraform camp, but I've increasingly incorporated Pulumi into my toolkit. This transition wasn't without its challenges, but it's given me valuable perspective on where these tools excel and where they fall short.

The Terraform Foundation

When I first started automating our cloud infrastructure, Terraform was the obvious choice. HashiCorp's creation offered a declarative approach with HCL (HashiCorp Configuration Language) that was purpose-built for infrastructure definitions. The workflow was straightforward: write your configuration, run terraform plan to see what would change, then terraform apply to make it happen.

What I appreciated most about Terraform was its maturity. The provider ecosystem was robust, and finding examples for even complex infrastructure setups was rarely a challenge. State management, while sometimes frustrating, was a solved problem with remote backends. Our team developed conventions and modules that served us well as we scaled our infrastructure across multiple cloud providers.

However, as our infrastructure grew more complex, I began to notice limitations. HCL, while powerful for infrastructure declaration, lacks the expressiveness of general-purpose programming languages. Conditional logic often felt clunky, and creating reusable abstractions sometimes required more boilerplate than seemed necessary.

Enter Pulumi: Programming Languages for Infrastructure

My first Pulumi project was experimental—a sandbox environment in GCP that wouldn't impact our production systems. What immediately struck me was how natural it felt to use TypeScript for infrastructure definition. Functions, classes, and loops that would have required workarounds in HCL just worked the way I expected.

The TypeScript support was particularly valuable. Having actual compiler checks before deployment caught errors that would have only surfaced during a Terraform plan or, worse, after applying changes. The ability to use npm packages meant we weren't reinventing wheels for common patterns.

But Pulumi's learning curve was steeper than I anticipated. The documentation, while improving, didn't have the wealth of examples that Terraform boasted. Understanding how Pulumi's state management differed from Terraform's took time, and explaining these concepts to team members who were comfortable with Terraform required patience.

The Coexistence Strategy

Rather than making a wholesale switch, we adopted a pragmatic approach. New projects, particularly those with complex logic or that benefited from TypeScript's type system, used Pulumi. Existing Terraform infrastructure remained as is, unless there was compelling reason to migrate.

This hybrid approach has served us well. We're leveraging the strengths of both tools while minimizing disruption. Some insights from this coexistence phase:

1. Migration isn't all-or-nothing. You can start with individual components and gradually shift more complex infrastructure to Pulumi as your team's comfort level increases.

2. Team skill sets matter. Developers with programming backgrounds tend to grasp Pulumi quickly, while those with more ops-focused experience often prefer Terraform's straightforward approach.

3. Some infrastructure is better suited to Pulumi. When we need complex conditional logic or integration with existing code, Pulumi shines. For simpler, declarative resources, Terraform's conciseness is hard to beat.

4. The ecosystem differences are narrowing. Both tools have expanded their provider coverage, though Terraform still has the edge in more niche or specialized services.

After working extensively with both tools, here are my key observations:

Terraform Strengths

• More mature ecosystem and community

• Simpler to get started with for those new to IaC

• Excellent provider coverage, even for less common services

• Strong convention-based approach that scales across teams

Pulumi Strengths

• Full programming language capabilities reduce boilerplate and improve expressiveness

• Strong typing catches errors earlier in the development cycle

• Better integration with existing development workflows and tools

• More natural abstractions through OOP and functional patterns

Pain Points in Transition

• Knowledge transfer is significant; Pulumi thinks differently about some core concepts

• Explaining the benefits to management requires practical demonstrations

• Some team members will resist the change, particularly if they're less comfortable with programming

• Maintaining both systems requires discipline in documentation and knowledge sharing

Conclusion: It's Not About Replacement

Is Pulumi replacing Terraform? I don't think that's the right question. In our organisation, both tools have found their place. What we're seeing isn't replacement but specialisation—using the right tool for the right job.

For teams starting fresh with IaC today, Pulumi offers compelling advantages, especially if your team has strong software development skills. For organisations with significant investment in Terraform, wholesale migration probably isn't worth the disruption, but selective adoption of Pulumi for new projects or complex components might deliver significant benefits.

The future of Infrastructure as Code isn't a winner-take-all scenario between Terraform and Pulumi. Instead, I expect we'll continue to see these tools evolve in response to each other, with both finding their niches in the modern cloud engineering toolkit. The real winner is us—the engineers who now have more powerful, flexible options for managing our increasingly complex infrastructure.