Terraform vs Pulumi vs Cloud Deployment Manager - Choosing Your GCP IaC Tool

Infrastructure as Code (IaC) has become essential for managing cloud resources efficiently and consistently. Google Cloud Platform (GCP) offers several IaC tools, with Terraform, Pulumi, and Cloud Deployment Manager being the most prominent. Choosing the right tool depends on your team’s skills, project requirements, and preferences. This blog post compares these three tools, focusing on language differences, state management, and community support, to help you make an informed decision.

Language and Syntax

One of the most significant differences between these tools lies in the languages they use to define infrastructure.

• Terraform: Uses HashiCorp Configuration Language (HCL), a declarative language designed specifically for infrastructure management. HCL aims to be human-readable and relatively easy to learn, focusing on what you want to provision rather than how.

  resource "google_compute_instance" "default" {
    name         = "terraform-instance"
    machine_type = "f1-micro"
    zone         = "us-central1-a"
  
    boot_disk {
      initialize_params {
        image = "debian-cloud/debian-9"
      }
    }
  
    network_interface {
      network = "default"
    }
  }
  

• Pulumi: Supports general-purpose programming languages like Python, JavaScript/TypeScript, Go, and C#. This allows you to leverage existing programming skills and libraries for more complex infrastructure logic, including loops, conditionals, and custom functions.

  import pulumi
  import pulumi_gcp as gcp
  
  instance = gcp.compute.Instance("pulumi-instance",
      machine_type="f1-micro",
      zone="us-central1-a",
      boot_disk=gcp.compute.InstanceBootDiskArgs(
          initialize_params=gcp.compute.InstanceBootDiskInitializeParamsArgs(
              image="debian-cloud/debian-9",
          ),
      ),
      network_interfaces=[gcp.compute.InstanceNetworkInterfaceArgs(
          network="default",
      )])
  

• Cloud Deployment Manager: Utilizes YAML (or Jinja2 templates) for defining infrastructure. While YAML is relatively easy to read, it can become verbose and challenging to manage for complex deployments. It’s tightly integrated with GCP and is often a good starting point for simple deployments.

  resources:
  - name: the-instance
    type: compute.v1.instance
    properties:
      zone: us-central1-a
      machineType: zones/us-central1-a/machineTypes/f1-micro
      disks:
      - deviceName: boot
        type: PERSISTENT
        boot: true
        autoDelete: true
        initializeParams:
          sourceImage: projects/debian-cloud/global/images/family/debian-9
      networkInterfaces:
      - network: global/networks/default
  

Summary of Language Differences:

Feature	Terraform (HCL)	Pulumi (Python/JS/Go)	Cloud Deployment Manager (YAML)
Language Paradigm	Declarative	Imperative/Declarative	Declarative
Expressiveness	Limited	High	Limited
Learning Curve	Relatively Easy	Depends on Language	Relatively Easy

State Management

State management is crucial for IaC tools, as it tracks the current state of your infrastructure and enables proper planning and execution of changes.

• Terraform: Stores state in a state file (usually terraform.tfstate). For production environments, it’s highly recommended to use remote state management solutions like Google Cloud Storage (GCS) to ensure collaboration, versioning, and security. Terraform Cloud is HashiCorp’s managed solution for state management and collaboration.

• Pulumi: Manages state through its own cloud-based service (Pulumi Service) or a self-managed backend using object storage like GCS or AWS S3. The Pulumi Service offers features like state locking, secrets management, and collaboration.

• Cloud Deployment Manager: Also uses a cloud-based state management system, tightly integrated with GCP. This simplifies setup but can limit flexibility if you need to manage resources across multiple cloud providers.

Comparison of State Management:

Feature	Terraform	Pulumi	Cloud Deployment Manager
State Storage	Local/Remote (GCS/S3)	Pulumi Service/GCS/S3	GCP Integrated
Collaboration	Requires Remote State	Built-in via Service	GCP IAM
Secrets Management	Requires Additional Tooling	Built-in	Requires Additional Tooling

Community Support and Ecosystem

A strong community and a rich ecosystem of modules and providers can significantly simplify your IaC journey.

• Terraform: Boasts the largest and most mature community, with extensive documentation, tutorials, and modules available in the Terraform Registry. This vast ecosystem makes it easier to find pre-built components for common infrastructure patterns.

• Pulumi: Has a growing community and a good selection of providers for various cloud platforms and services. Because Pulumi uses general-purpose languages, you can also leverage existing libraries and tools from those ecosystems.

• Cloud Deployment Manager: Has the smallest community compared to Terraform and Pulumi. Its ecosystem is primarily focused on GCP services and features.

Community and Ecosystem Summary:

Feature	Terraform	Pulumi	Cloud Deployment Manager
Community Size	Largest	Growing	Smallest
Module/Provider Availability	Extensive	Good	Limited

Conclusion

Choosing the right IaC tool for GCP depends on your specific needs and priorities.

• Terraform: Is a solid choice if you prefer a dedicated configuration language (HCL), a vast community, and a wide range of modules.
• Pulumi: Is excellent if your team is comfortable with general-purpose programming languages and you need more flexibility for complex infrastructure logic.
• Cloud Deployment Manager: Is a good starting point for simple GCP deployments, especially if you want a tool tightly integrated with GCP services.

Consider evaluating each tool with a small pilot project to determine which best fits your team’s workflow and requirements. Good luck!