Infrastructure as Code (IaC) has become essential for managing cloud resources at scale. Terraform and Pulumi are the two leading IaC tools in 2026, each with distinct philosophies and capabilities. This guide provides a comprehensive comparison to help you choose the right tool for your infrastructure needs.
Fundamental Differences
The core difference lies in their approach to configuration. Terraform uses HCL (HashiCorp Configuration Language), a declarative DSL designed specifically for infrastructure. Pulumi uses general-purpose programming languages like TypeScript, Python, Go, and C#, enabling traditional programming constructs.
- Terraform: Domain-specific language (HCL), extensive provider ecosystem, mature tooling
- Pulumi: General-purpose languages, native IDE support, testing with standard frameworks
Terraform in Action
Terraform's declarative approach makes infrastructure configurations readable and predictable. The extensive provider ecosystem covers virtually every cloud service and many third-party tools.
# Terraform - AWS EKS Cluster with VPC
terraform {
required_version = ">= 1.6"
required_providers {
aws = {
source = "hashicorp/aws"
version = "~> 5.0"
}
}
backend "s3" {
bucket = "my-terraform-state"
key = "prod/eks/terraform.tfstate"
region = "us-west-2"
encrypt = true
dynamodb_table = "terraform-locks"
}
}
provider "aws" {
region = var.aws_region
default_tags {
tags = {
Environment = var.environment
ManagedBy = "terraform"
Project = var.project_name
}
}
}
# Variables
variable "aws_region" {
type = string
default = "us-west-2"
}
variable "environment" {
type = string
default = "production"
}
variable "project_name" {
type = string
default = "my-app"
}
variable "cluster_version" {
type = string
default = "1.28"
}
# VPC Module
module "vpc" {
source = "terraform-aws-modules/vpc/aws"
version = "5.0.0"
name = "${var.project_name}-vpc"
cidr = "10.0.0.0/16"
azs = ["${var.aws_region}a", "${var.aws_region}b", "${var.aws_region}c"]
private_subnets = ["10.0.1.0/24", "10.0.2.0/24", "10.0.3.0/24"]
public_subnets = ["10.0.101.0/24", "10.0.102.0/24", "10.0.103.0/24"]
enable_nat_gateway = true
single_nat_gateway = var.environment != "production"
enable_dns_hostnames = true
public_subnet_tags = {
"kubernetes.io/role/elb" = 1
}
private_subnet_tags = {
"kubernetes.io/role/internal-elb" = 1
}
}
# EKS Module
module "eks" {
source = "terraform-aws-modules/eks/aws"
version = "19.0.0"
cluster_name = "${var.project_name}-eks"
cluster_version = var.cluster_version
vpc_id = module.vpc.vpc_id
subnet_ids = module.vpc.private_subnets
cluster_endpoint_public_access = true
eks_managed_node_groups = {
general = {
desired_size = 2
min_size = 1
max_size = 10
instance_types = ["t3.large"]
capacity_type = "ON_DEMAND"
labels = {
role = "general"
}
}
}
# Enable IRSA
enable_irsa = true
}
# Outputs
output "cluster_endpoint" {
description = "EKS cluster endpoint"
value = module.eks.cluster_endpoint
}
output "cluster_name" {
description = "EKS cluster name"
value = module.eks.cluster_name
}Pulumi in Action
Pulumi's use of real programming languages enables powerful abstractions, loops, conditionals, and integration with existing codebases. This approach is particularly valuable for teams with strong software engineering practices.
// Pulumi - AWS EKS Cluster with VPC (TypeScript)
import * as pulumi from "@pulumi/pulumi";
import * as aws from "@pulumi/aws";
import * as eks from "@pulumi/eks";
const config = new pulumi.Config();
const environment = config.get("environment") || "production";
const projectName = config.get("projectName") || "my-app";
const clusterVersion = config.get("clusterVersion") || "1.28";
// VPC Configuration
const vpc = new aws.ec2.Vpc(`${projectName}-vpc`, {
cidrBlock: "10.0.0.0/16",
enableDnsHostnames: true,
enableDnsSupport: true,
tags: {
Name: `${projectName}-vpc`,
Environment: environment,
},
});
// Create subnets programmatically
const azs = ["us-west-2a", "us-west-2b", "us-west-2c"];
const publicSubnets: aws.ec2.Subnet[] = [];
const privateSubnets: aws.ec2.Subnet[] = [];
azs.forEach((az, index) => {
// Public subnets
const publicSubnet = new aws.ec2.Subnet(`public-subnet-${index}`, {
vpcId: vpc.id,
cidrBlock: `10.0.${100 + index}.0/24`,
availabilityZone: az,
mapPublicIpOnLaunch: true,
tags: {
Name: `${projectName}-public-${az}`,
"kubernetes.io/role/elb": "1",
},
});
publicSubnets.push(publicSubnet);
// Private subnets
const privateSubnet = new aws.ec2.Subnet(`private-subnet-${index}`, {
vpcId: vpc.id,
cidrBlock: `10.0.${index}.0/24`,
availabilityZone: az,
tags: {
Name: `${projectName}-private-${az}`,
"kubernetes.io/role/internal-elb": "1",
},
});
privateSubnets.push(privateSubnet);
});
// Internet Gateway
const igw = new aws.ec2.InternetGateway(`${projectName}-igw`, {
vpcId: vpc.id,
});
// NAT Gateway (conditional based on environment)
const eip = new aws.ec2.Eip(`${projectName}-eip`, {
domain: "vpc",
});
const natGateway = new aws.ec2.NatGateway(`${projectName}-nat`, {
allocationId: eip.id,
subnetId: publicSubnets[0].id,
});
// EKS Cluster using Pulumi's EKS package
const cluster = new eks.Cluster(`${projectName}-eks`, {
vpcId: vpc.id,
subnetIds: privateSubnets.map(s => s.id),
instanceType: "t3.large",
desiredCapacity: 2,
minSize: 1,
maxSize: 10,
version: clusterVersion,
nodeAssociatePublicIpAddress: false,
enabledClusterLogTypes: [
"api",
"audit",
"authenticator",
],
tags: {
Environment: environment,
},
});
// Custom component for reusable infrastructure
class MonitoredService extends pulumi.ComponentResource {
public readonly loadBalancer: aws.lb.LoadBalancer;
public readonly targetGroup: aws.lb.TargetGroup;
constructor(
name: string,
args: {
vpcId: pulumi.Input<string>;
subnetIds: pulumi.Input<string>[];
port: number;
healthCheckPath?: string;
},
opts?: pulumi.ComponentResourceOptions
) {
super("custom:infrastructure:MonitoredService", name, {}, opts);
this.targetGroup = new aws.lb.TargetGroup(
`${name}-tg`,
{
port: args.port,
protocol: "HTTP",
vpcId: args.vpcId,
healthCheck: {
path: args.healthCheckPath || "/health",
healthyThreshold: 2,
unhealthyThreshold: 3,
},
},
{ parent: this }
);
this.loadBalancer = new aws.lb.LoadBalancer(
`${name}-alb`,
{
loadBalancerType: "application",
subnets: args.subnetIds,
securityGroups: [],
},
{ parent: this }
);
this.registerOutputs({
loadBalancerDns: this.loadBalancer.dnsName,
});
}
}
// Exports
export const clusterName = cluster.eksCluster.name;
export const kubeconfig = cluster.kubeconfig;
export const vpcId = vpc.id;State Management Comparison
Both tools track infrastructure state, but handle it differently. Understanding state management is crucial for team workflows and disaster recovery.
# Terraform State Commands
terraform state list # List resources in state
terraform state show aws_instance.web # Show resource details
terraform state mv old_name new_name # Rename resource
terraform state rm aws_instance.web # Remove from state (not cloud)
terraform import aws_instance.web i-123 # Import existing resource
# Terraform State Backends
# - S3 + DynamoDB (AWS)
# - Azure Blob Storage
# - Google Cloud Storage
# - Terraform Cloud
# Pulumi State Commands
pulumi stack ls # List stacks
pulumi stack export > backup.json # Export state
pulumi stack import < backup.json # Import state
pulumi state delete urn:pulumi:... # Delete from state
pulumi import aws:ec2:instance web i-123 # Import existing
# Pulumi State Backends
# - Pulumi Cloud (default, free tier available)
# - S3
# - Azure Blob
# - Google Cloud Storage
# - Local filesystemTesting Infrastructure Code
Testing is where Pulumi shines. Since it uses real programming languages, you can use standard testing frameworks. Terraform's testing options have improved but remain more limited.
// Pulumi - Unit Testing with Mocha
import * as pulumi from "@pulumi/pulumi";
import { expect } from "chai";
// Mock the Pulumi runtime for testing
pulumi.runtime.setMocks({
newResource: (args) => {
return { id: `${args.name}-id`, state: args.inputs };
},
call: (args) => args.inputs,
});
describe("Infrastructure", () => {
let infra: typeof import("./index");
before(async () => {
infra = await import("./index");
});
describe("VPC", () => {
it("should have DNS support enabled", async () => {
const enableDnsSupport = await new Promise((resolve) =>
infra.vpc.enableDnsSupport.apply(resolve)
);
expect(enableDnsSupport).to.be.true;
});
it("should use the correct CIDR block", async () => {
const cidrBlock = await new Promise((resolve) =>
infra.vpc.cidrBlock.apply(resolve)
);
expect(cidrBlock).to.equal("10.0.0.0/16");
});
});
describe("EKS Cluster", () => {
it("should have minimum 2 nodes", async () => {
const minSize = await new Promise((resolve) =>
infra.cluster.minSize.apply(resolve)
);
expect(minSize).to.be.at.least(1);
});
});
});# Terraform - Testing with terraform test (1.6+)
# tests/vpc_test.tftest.hcl
variables {
environment = "test"
aws_region = "us-west-2"
}
run "vpc_creation" {
command = plan
assert {
condition = module.vpc.vpc_cidr_block == "10.0.0.0/16"
error_message = "VPC CIDR block is incorrect"
}
assert {
condition = length(module.vpc.private_subnets) == 3
error_message = "Should have 3 private subnets"
}
}
run "eks_cluster" {
command = plan
assert {
condition = module.eks.cluster_version == var.cluster_version
error_message = "EKS version mismatch"
}
}Decision Framework
Choosing Between Terraform and Pulumi
Choose Terraform if:
- Team has limited programming experience
- You need maximum provider coverage
- Organization already uses HashiCorp tools
- Declarative syntax is preferred
- You want mature, battle-tested tooling
Choose Pulumi if:
- Team has strong software engineering skills
- Complex logic and abstractions are needed
- Testing infrastructure is a priority
- Type safety and IDE support are valued
- You want to share code with application teams
Conclusion
Both Terraform and Pulumi are excellent choices for infrastructure as code in 2026. Terraform remains the industry standard with unmatched provider support and mature tooling. Pulumi offers a modern alternative that appeals to teams who want to apply software engineering practices to infrastructure.
Consider your team's skills, existing tooling, and specific requirements when choosing. Many organizations successfully use both tools for different use cases.
Need help implementing infrastructure as code for your organization? Contact Jishu Labs for expert DevOps consulting and implementation services.
About David Kumar
David Kumar is the DevOps Lead at Jishu Labs with expertise in cloud infrastructure and automation. He has implemented IaC solutions for enterprise clients across AWS, Azure, and GCP.