Explain Terraform vs Pulumi.

Terraform vs Pulumi compares two Infrastructure-as-Code (IaC) tools—Terraform uses a declarative language (HCL), while Pulumi leverages general-purpose languages like TypeScript, Python, Go, and C# to provision and manage cloud resources.

When to Use

Terraform: Multi-cloud standardization, large teams, and mature module/registry workflows.
Pulumi: Teams wanting to reuse business logic, write unit tests, and manage infra directly in real programming languages.

Example

Terraform: Write HCL to define an AWS S3 bucket, run terraform plan → apply.
Pulumi: Use TypeScript to create the same bucket, run pulumi preview → up, reuse npm packages.

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Why Is It Important

The choice shapes developer velocity, team collaboration, and cloud governance. It affects state management, testing, and auditability.

Interview Tips

Define both tools clearly.
Highlight Terraform’s declarative approach vs Pulumi’s programming language flexibility.
Mention state backends, plan vs preview, policy-as-code, and provider ecosystems.

Trade-offs

Terraform: Easy to learn, huge ecosystem, but limited logic support.
Pulumi: More expressive, reusable code/testing, but risk of imperative anti-patterns and smaller ecosystem.

Pitfalls

Mixing business logic with infra code.
Committing secrets/state to repos.
Overusing hacks like null_resource or local-exec.
Misconception: “Terraform isn’t testable” or “Pulumi is only for devs”—both can be production-grade.

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System Design Interview

System Design Fundamentals

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