Ansible vs Terraform

Ansible and Terraform solve different but complementary problems. Terraform provisions infrastructure (create a VPC, launch an EC2 instance, set up an RDS database). Ansible configures what runs on that infrastructure (install packages, deploy code, manage services). Many teams use both together.

Different Tools, Different Jobs

Terraform — Infrastructure Provisioning

Terraform excels at creating and managing cloud resources. You declare what infrastructure you want, Terraform computes the diff against its state file, and applies the minimum set of changes. It handles dependencies between resources automatically.

Ansible — Configuration Management

Ansible excels at configuring servers after they exist. It connects via SSH, runs tasks in order, and ensures systems reach the desired configuration. It is agentless, meaning no software needs to be installed on target machines.

Procedural vs Declarative

Ansible playbooks are procedural — tasks execute sequentially. While most modules are idempotent (running them twice produces the same result), the execution model is step-by-step.

Terraform is purely declarative. You define the end state, and Terraform figures out how to get there. This makes it easier to reason about what your infrastructure looks like at any point.

Using Both Together

The common pattern is:

1. Terraform provisions the infrastructure — VPCs, subnets, security groups, EC2 instances, RDS databases
2. Ansible configures the servers — installs software, deploys applications, manages configuration files

Terraform outputs (like IP addresses and DNS names) feed into Ansible inventories, creating a smooth end-to-end automation pipeline.

When They Overlap

Terraform has provisioners (like remote-exec) that can run scripts on created resources, and Ansible has cloud modules that can provision infrastructure. However, using each tool for its primary purpose produces cleaner, more maintainable automation.

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