| Purpose | Infrastructure provisioning | Configuration management and task automation | Configuration management and server automation |
| Architecture | Client-only, interacts directly with provider APIs | Agentless, uses SSH (or WinRM for Windows) for push-based execution | Client-server model with Puppet Server and agents (pull-based) |
| Language | HCL (HashiCorp Configuration Language) or JSON | YAML (playbooks) | Puppet DSL (Ruby-based) |
| Idempotency | Yes, reconciles desired state with actual state via state file | Yes, tasks only apply changes when needed | Yes, ensures consistent state via catalog application |
| State Management | Uses terraform.tfstate to track infrastructure state (critical, stored locally or remotely) | Stateless; relies on system state and idempotent tasks | State managed via PuppetDB and catalogs, compiled by Puppet Server |
| Key Components | Resources, providers, modules, state file, backend | Playbooks, inventory, roles, modules, tasks | Manifests, modules, resources, Facter, Hiera, PuppetDB |
| Execution Model | Declarative; terraform plan previews, terraform apply executes | Push-based; ansible-playbook pushes tasks to hosts | Pull-based; agents poll Puppet Server for catalogs |
| Sensitive Data Handling | Variables, .tfvars, remote backends (e.g., S3), or Vault integration | Ansible Vault, external tools (e.g., HashiCorp Vault) | Hiera with hiera-eyaml, external tools (e.g., Vault) |
| Modularity | Modules for reusable configurations, stored in Terraform Registry | Roles and collections (modules & plugins), stored in Ansible Galaxy | Modules for reusable manifests, stored in Puppet Forge |
| Inventory/Node Management | Not applicable; manages infrastructure, not nodes | Static or dynamic inventory (e.g., aws_ec2 plugin) | Node classification via Puppet Server or external node classifiers (ENC) |
| Environment Management | Workspaces or separate directories with .tfvars for dev/staging/prod | Separate inventories or group_vars for dev/prod | Environments in /etc/puppetlabs/code/environments with Hiera data |
| Error Handling | Debug with terraform plan, logs, or terraform apply -replace for resource issues (instead of taint) | Use ignore_errors, failed_when, or --verbose for debugging | Debug with puppet agent --debug, logs, or fail() function |
| Testing Tools | terraform validate, Terratest, Checkov, TFLint | ansible-lint, Molecule, --check mode | puppet-lint, rspec-puppet, puppet parser validate |
| Scalability | Scales via remote backends (e.g., S3, Terraform Cloud) with locking | Scales with strategy: free, forks, or Ansible Tower | Scales with Puppetserver tuning, PuppetDB, or HA Puppet Server |
| Security Best Practices | Encrypt state files, use IAM roles, remote backends with locking | Use Ansible Vault, secure SSH keys, restrict playbook access | Use SSL for Puppet Server, Hiera encryption, RBAC |
| Common Integrations | Terraform Cloud, Infracost, AWS/GCP/Azure providers | Ansible Tower/AWX, dynamic inventory plugins, Vault | Puppet Enterprise, PuppetDB, r10k, Puppet Forge |
| Use Case Example | Provision AWS VPC, EC2, and RDS across regions | Configure Nginx, manage users on multiple servers | Manage Apache, MySQL configs, and services on Linux/Windows servers |
| Key differenciator | Provisioning focus | Agentless simplicity | Client-server robustness |