Terraform vs Ansible: Provisioning vs Configuration Management

Sun, 02 Aug 2026 11:25:27 +0900

Overview

Terraform and Ansible are both infrastructure-as-code tools but solve different problems: Terraform declaratively provisions and tracks cloud infrastructure using a state file, while Ansible procedurally configures and manages software on existing hosts with no persistent state. Many teams use them together — Terraform to stand up infrastructure, Ansible to configure it.

Comparison Diagram

Comparison Table

Aspect	Terraform	Ansible
Primary purpose	Provision and tear down cloud/infra resources (VMs, networks, DBs)	Configure software and manage state on existing hosts
Configuration language	HCL (HashiCorp Configuration Language), declarative	YAML playbooks, procedural task lists
Execution model	Builds a dependency graph and applies changes in parallel where possible	Executes tasks sequentially, in order, per host
State management	Maintains a state file mapping config to real resources	Stateless — queries live system facts on each run
Idempotency approach	Diffs desired config against state file before acting	Each module checks current condition before making a change
Connectivity/agent requirement	Agentless — calls cloud/provider APIs directly	Agentless — connects over SSH or WinRM to target hosts
Failure & recovery handling	Partial applies are resolved by re-running against the state file	Reruns the playbook from the start; tasks are re-checked, not resumed

Key Differences

Terraform tracks infrastructure in a persistent state file; Ansible has no state store and reads live system facts each run.
Terraform resolves a dependency graph to apply changes in parallel; Ansible runs tasks sequentially.
Terraform talks to infrastructure through provider APIs; Ansible connects to hosts via SSH/WinRM.
Terraform is built for provisioning infra; Ansible is built for configuration of what already exists.
They’re commonly paired: Terraform creates the servers, then Ansible configures them.

When to Use Each

Terraform

Declarative vs Imperative IaC: Describing the End State vs Scripting the Steps

Sun, 02 Aug 2026 08:55:05 +0900

Overview

Declarative IaC (e.g. Terraform, CloudFormation) has you specify the desired end state of infrastructure and lets an engine figure out how to get there. Imperative IaC (e.g. shell scripts, Chef recipes, raw CLI calls) has you write the exact sequence of commands to execute. The distinction matters because it determines who — you or the tool — is responsible for ordering, idempotency, and reconciling drift.

Comparison Diagram

Comparison Table

Aspect	Declarative	Imperative
Authoring model	Write a desired-state spec	Write an ordered command list
Execution engine	Resolves a dependency graph	Runs a sequential interpreter
State tracking	Maintains a state file	Stateless execution
Applying changes	Single apply command	Run the script/playbook
Ordering & dependencies	Auto-resolved by engine	Manually sequenced by author
Idempotency	Guaranteed by design	Developer-enforced
Drift detection	Built-in plan diff	Not built-in
Failure handling	Partial apply, replan	Manual rollback

Key Differences

Declarative code answers ‘what’, imperative code answers ‘how’.
Declarative tools rely on a state file to know current vs. desired infrastructure; imperative scripts have no memory of prior runs.
Idempotent re-runs are automatic in declarative tools but must be hand-coded (checks, conditionals) in imperative scripts.
Declarative engines build a dependency graph to order operations; imperative code hardcodes that order line by line.
Drift correction in declarative IaC is a matter of re-running plan/apply; imperative approaches require re-running or rewriting the exact script.

When to Use Each

Declarative

Terraform on IT Comparison

Terraform vs Ansible: Provisioning vs Configuration Management

Overview

Comparison Diagram

Comparison Table

Key Differences

When to Use Each

Declarative vs Imperative IaC: Describing the End State vs Scripting the Steps

Overview

Comparison Diagram

Comparison Table

Key Differences

When to Use Each