terraform

Initialize a Terraform working directory

$ terraform init

$ terraform plan

$ terraform apply

$ terraform destroy

$ terraform fmt

$ terraform validate

$ terraform show

$ terraform state list

$ terraform import [resource_type.name] [id]

terraform command [options] [args]

terraform is an infrastructure as code tool for building, changing, and versioning cloud infrastructure safely and efficiently. It uses declarative configuration files to describe desired infrastructure state.
Configuration is written in HCL (HashiCorp Configuration Language) defining resources like servers, networks, and databases. Terraform communicates with cloud providers (AWS, Azure, GCP, etc.) via plugins called providers.
The workflow is: init (setup), plan (preview), apply (execute). State is tracked in terraform.tfstate, enabling Terraform to know what exists and what needs changing.
Workspaces allow managing multiple environments (dev, staging, prod) from the same configuration with different state files.

init

Initialize working directory, download providers

Create execution plan showing proposed changes

Apply changes to reach desired state

Destroy all managed infrastructure

Format configuration files to canonical style

Check configuration syntax and consistency

Display current state or saved plan

Read output values from state

Advanced state management commands

Import existing infrastructure into state

Manage workspaces

Skip interactive approval (apply/destroy)

Set input variable

Load variables from file

Target specific resource

Limit concurrent operations

terraform.tfvars

Default variable values file, automatically loaded when present in the working directory

Additional variable files automatically loaded alphabetically

CLI configuration file for provider installation methods, credentials, and plugin cache

Environment variables prefixed with TFVAR set input variable values

Override the default CLI configuration file location

State files contain sensitive information (passwords, keys) and should be stored securely. Use remote backends (S3, Terraform Cloud) for team collaboration and state locking.
terraform destroy is irreversible. Always run plan first and verify the destruction plan carefully.
Provider versions should be pinned in configuration to ensure reproducibility. Unexpected provider updates can cause issues.
Changes made outside Terraform (manual console changes) cause state drift. Use terraform refresh or import to reconcile.

Terraform was created by HashiCorp and first released in 2014 by Mitchell Hashimoto. It pioneered the "infrastructure as code" approach for multi-cloud provisioning and became the de facto standard for declarative infrastructure management.

aws(1), ansible(1), pulumi(1), tofu(1)