TerraformAnsibleIaCDevOps

Terraform vs Ansible: When to Use Which

InfoScale Team·1 March 2026· 9 min

"What's better — Terraform or Ansible?" is one of the most common DevOps interview questions. The correct answer: it depends on the task. The wrong answer: pick one tool and use it everywhere.

Core Difference: Declarative vs Imperative

Terraform is a declarative tool. You describe the desired infrastructure state, and Terraform figures out what to create, modify, or delete. This is ideal for managing cloud resources: VPC, EC2, RDS, IAM roles.

Ansible is imperative. You describe a sequence of actions: install a package, copy a file, restart a service. This makes it a powerful tool for server configuration and task orchestration.

Comparison by Key Parameters

Parameter	Terraform	Ansible
Approach	Declarative	Imperative
Primary use	Infrastructure provisioning	Server configuration
State management	State file (terraform.tfstate)	Stateless (idempotent)
Language	HCL (HashiCorp Config Language)	YAML (Playbooks)
Agent required	Not required	Not required (SSH)
Cloud providers	Excellent (800+ providers)	Good via modules
Learning curve	Medium (HCL + concepts)	Low (YAML)

When to Use Terraform

Creating and managing cloud infrastructure (AWS, GCP, Azure, Yandex Cloud)

Multi-cloud or multi-region deployments with unified state

Network management: VPC, subnets, security groups, load balancers

Kubernetes clusters (EKS, GKE, AKS) and managed services (RDS, ElastiCache)

When infrastructure change history via git is important

# Пример: создание EKS кластера в Terraform
resource "aws_eks_cluster" "production" {
  name = "infoscale-prod"
  role_arn = aws_iam_role.eks.arn
  version = "1.29"
  vpc_config {
    subnet_ids = aws_subnet.private[*].id
  }
}

When to Use Ansible

Server configuration after creation: installing packages, configuring nginx, systemd

Deploying applications on bare-metal or VMs without Kubernetes

Automating routine tasks: updates, backups, log rotation

Orchestrating multi-step processes with conditions and error handling

Managing Kafka, PostgreSQL, Redis configuration on custom servers

# Пример: установка и настройка Kafka через Ansible
- name: Install Kafka
  hosts: kafka_nodes
  tasks:
    - name: Download distribution
      get_url:
        url: https://downloads.apache.org/kafka/3.7.0/kafka_2.13-3.7.0.tgz
        dest: /opt/kafka.tgz

Common Mistakes When Choosing a Tool

Using Ansible for cloud resource provisioning

Ansible doesn't store state. If a resource already exists, the playbook may fail or create a duplicate. Terraform is better suited for this.

Using Terraform for application configuration inside VMs

Terraform creates resources but isn't designed for managing config files, services, and packages inside the OS. That's Ansible's domain.

Choosing one tool for everything

In real projects, Terraform and Ansible work together: Terraform creates infrastructure, Ansible configures it. They're not competitors — they're a pair.

Real Scenario from Our Project

In the VPN service project (12,000+ users), we used both tools together. Here's what the pipeline looked like:

Terraform—Creates VPC, EC2 instances, security groups, load balancer in AWS

Ansible—Installs OpenVPN, configures firewall, deploys configs

ArgoCD—Deploys application to Kubernetes cluster created by Terraform

Ansible—Automates updates and certificate rotation on schedule

Result: deploying an identical cluster from scratch takes 30 minutes. Before — 2-3 days of manual work.

Summary

Terraform — for creating infrastructure. Ansible — for configuring it. Together they cover the full lifecycle: from an empty cloud to a working production environment. If you're only using one of them — you're either overcomplicating where you shouldn't, or missing opportunities.

Need Help with IaC in Your Project?

We set up Terraform + Ansible stacks for production infrastructure. We'll tell you what works best for your case.

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