Terraform or Pulumi? There is only one long term choice

Terraform and Pulumi both let you manage cloud infrastructure as code, and they solve the same problem in different ways. This post walks through where the two overlap, where they part ways, and why Terraform is the better long-term choice.

Similarities between Terraform and Pulumi

Start with what they have in common. Both tools are open-source and let you define cloud infrastructure in code. They work with multiple cloud providers, including AWS, Azure, GCP, and Kubernetes. Both also automate the deployment and management of that infrastructure, and both plug into Continuous Integration/Continuous Deployment (CI/CD) pipelines.

Differences between Terraform and Pulumi

Terraform and Pulumi differ in their approach and implementation. Terraform uses a declarative approach, while Pulumi uses an imperative approach. In Terraform, you define the desired state of your infrastructure, and Terraform figures out the actions needed to achieve that state. In contrast, with Pulumi, you write code that explicitly describes the actions to be taken.

The other big difference is language support. Terraform uses HashiCorp Configuration Language (HCL), which is similar to JSON, whereas Pulumi supports multiple languages, including JavaScript, TypeScript, Python, and Go. That lets developers use the language they already know.

Terraform has been around for much longer than Pulumi and has a larger community and ecosystem. Terraform modules, which are reusable pieces of infrastructure code, are easy to find, and there's a module for most use cases. Pulumi is relatively new, and its ecosystem is still growing.

Why Terraform is the better long-term choice

Pulumi's multi-language support and imperative approach can look appealing, but a few things still tip the balance toward Terraform for the long haul.

The ecosystem is one factor. Terraform has a much larger community, so there are more modules to pull from and more people who can help when you get stuck.

There's also the matter of state. Terraform's declarative approach makes it easier to reason about what your infrastructure actually looks like. With Pulumi's imperative approach, the current state can be harder to pin down once the use case gets complicated.

Maturity counts too. Terraform has been battle-tested over the years and plenty of large enterprises use it to run their cloud infrastructure. It's mature and stable, whereas Pulumi is newer and doesn't have the same track record.

The last point is the learning curve. Terraform's HCL is simple and easy to learn, similar to JSON, so developers can get productive quickly. Pulumi's support for multiple languages adds flexibility, but it also makes things harder to pick up at the start.

Pulumi has real strengths, and for some teams the language flexibility will win out. For most teams managing cloud infrastructure in code, though, Terraform's ecosystem, declarative model, stability, and simple HCL make it the safer bet over time.

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