Pulumi vs Terraform in 2026: Infrastructure as Code with Real Programming Languages

For the past decade, Terraform has been the undisputed king of Infrastructure as Code. Its declarative HCL syntax, massive provider ecosystem, and state management model became the industry standard. But Terraform has pain points: HCL is a limited domain-specific language (no real loops, limited conditionals, no abstractions), the state file is a constant source of problems, and the BSL license change in 2023 created uncertainty for commercial users.

Pulumi takes a fundamentally different approach: write your infrastructure in real programming languages — TypeScript, Python, Go, C#, Java — with real loops, conditionals, functions, classes, and testing frameworks. This guide compares both tools across the dimensions that matter for production infrastructure management.

Syntax Comparison: HCL vs. Real Code

The most visible difference is the language. Here's the same infrastructure (a VPC with subnets, security groups, and an EC2 instance) in both tools:

# Terraform (HCL)
resource "aws_vpc" "main" {
  cidr_block = "10.0.0.0/16"
  tags = {
    Name = "main-vpc"
    Environment = var.environment
  }
}

resource "aws_subnet" "public" {
  count             = length(var.availability_zones)
  vpc_id            = aws_vpc.main.id
  cidr_block        = cidrsubnet(aws_vpc.main.cidr_block, 8, count.index)
  availability_zone = var.availability_zones[count.index]
  tags = {
    Name = "public-${var.availability_zones[count.index]}"
  }
}

resource "aws_security_group" "web" {
  name_prefix = "web-"
  vpc_id      = aws_vpc.main.id

  dynamic "ingress" {
    for_each = var.allowed_ports
    content {
      from_port   = ingress.value
      to_port     = ingress.value
      protocol    = "tcp"
      cidr_blocks = ["0.0.0.0/0"]
    }
  }
}

# Pulumi (TypeScript)
import * as aws from "@pulumi/aws";
import * as pulumi from "@pulumi/pulumi";

const config = new pulumi.Config();
const environment = config.require("environment");
const azs = ["us-east-1a", "us-east-1b", "us-east-1c"];
const allowedPorts = [80, 443, 8080];

const vpc = new aws.ec2.Vpc("main", {
  cidrBlock: "10.0.0.0/16",
  tags: { Name: "main-vpc", Environment: environment },
});

// Real programming: map over AZs with index
const publicSubnets = azs.map((az, index) =>
  new aws.ec2.Subnet(`public-${az}`, {
    vpcId: vpc.id,
    cidrBlock: `10.0.${index}.0/24`,
    availabilityZone: az,
    tags: { Name: `public-${az}` },
  })
);

// Real programming: map over ports
const webSg = new aws.ec2.SecurityGroup("web", {
  vpcId: vpc.id,
  ingress: allowedPorts.map(port => ({
    fromPort: port,
    toPort: port,
    protocol: "tcp",
    cidrBlocks: ["0.0.0.0/0"],
  })),
});

Where Pulumi Wins

Abstractions and reuse: In Pulumi, you create reusable infrastructure components using classes and functions — the same abstractions you use in application code. A "DatabaseCluster" component that creates an RDS instance, security group, parameter group, subnet group, and monitoring alarm can be a single TypeScript class that other teams import and use with new DatabaseCluster("mydb", { engine: "postgres", size: "large" }).

In Terraform, reuse happens through modules, which are limited: modules can't have conditional logic based on the caller's context, can't use complex data transformations, and have awkward variable passing semantics.

Testing: Pulumi programs are testable with standard testing frameworks (Jest, pytest, Go testing). You can unit test your infrastructure definitions, mock cloud provider responses, and run integration tests that actually provision resources. Terraform's testing story (terraform test, introduced in 1.6) is improving but still far behind.

// Pulumi unit test with Jest
import * as pulumi from "@pulumi/pulumi";
import { describe, it, expect, beforeAll } from "@jest/globals";

// Mock Pulumi runtime for testing
pulumi.runtime.setMocks({
  newResource: (args) => ({ id: args.name + "_id", state: args.inputs }),
  call: (args) => args.inputs,
});

describe("Infrastructure", () => {
  let infra: typeof import("./index");

  beforeAll(async () => {
    infra = await import("./index");
  });

  it("VPC should have correct CIDR block", (done) => {
    pulumi.all([infra.vpc.cidrBlock]).apply(([cidr]) => {
      expect(cidr).toBe("10.0.0.0/16");
      done();
    });
  });

  it("should create subnets in 3 AZs", (done) => {
    pulumi.all([infra.publicSubnets.length]).apply(([count]) => {
      expect(count).toBe(3);
      done();
    });
  });

  it("security group should allow ports 80 and 443", (done) => {
    pulumi.all([infra.webSg.ingress]).apply(([rules]) => {
      const ports = rules.map((r: any) => r.fromPort);
      expect(ports).toContain(80);
      expect(ports).toContain(443);
      done();
    });
  });
});

IDE support: Because Pulumi uses real languages, you get full IDE support: autocomplete for every resource property, type checking for configuration values, refactoring tools, go-to-definition, and inline documentation. HCL IDE support exists (via terraform-ls) but is significantly less capable.

Complex logic: Need to conditionally create resources based on a complex calculation? Need to transform data from one format to another? Need to call an API during infrastructure provisioning? In Pulumi, it's just code. In Terraform, you fight with HCL's limited expression syntax, for_each limitations, and null_resource hacks.

Where Terraform Wins

Ecosystem and provider coverage: Terraform has 3,000+ providers covering virtually every cloud service, SaaS tool, and infrastructure component. Pulumi has excellent coverage for major clouds (AWS, Azure, GCP) but has gaps for niche services. Pulumi can use Terraform providers via a bridge, but it's not always seamless.

Plan/apply workflow: terraform plan shows you exactly what will change before you apply. This is a critical safety feature for production infrastructure. Pulumi has pulumi preview, which is functionally equivalent, but Terraform's plan output is generally more detailed and mature.

Community and hiring: Terraform knowledge is more common in the job market. More blog posts, tutorials, Stack Overflow answers, and community modules exist for Terraform. If you're hiring infrastructure engineers, requiring Terraform experience gives you a larger candidate pool.

Simplicity for simple cases: For straightforward infrastructure (a few EC2 instances, a database, some S3 buckets), HCL's declarative syntax is arguably cleaner than imperative code. You don't need classes, functions, and abstractions to define 20 resources.

State management: Both tools use state files, but Terraform's state management is more mature. Terraform Cloud provides free remote state management with locking. Pulumi's state backends (Pulumi Cloud, S3, Azure Blob) work well but require more setup.

When to Choose Each

Choose Terraform when: Your team is already proficient with Terraform. You need maximum provider coverage. Your infrastructure is relatively simple. You want the largest community and ecosystem.

Choose Pulumi when: Your team is already proficient in TypeScript/Python/Go. You need complex logic, abstractions, and reusable components. You want to test your infrastructure with standard testing frameworks. You're building an Internal Developer Platform where infrastructure components are consumed as libraries.

Consider OpenTofu when: You want Terraform's syntax and workflow but with a truly open-source license (MPL 2.0). OpenTofu is a community fork of Terraform created after the BSL license change.

Migration: Terraform to Pulumi

Pulumi provides a migration tool (pulumi convert --from terraform) that converts HCL to Pulumi code in your language of choice. It handles most common patterns automatically, though complex modules may need manual adjustment. You can also import existing Terraform state into Pulumi without re-provisioning resources.

ZeonEdge helps organizations design, implement, and migrate Infrastructure as Code using Terraform, Pulumi, or OpenTofu. Contact our infrastructure team for a consultation.