Demo Terraform CLI

This lesson walks through common Terraform CLI commands using a minimal configuration and the random provider. You’ll learn the typical Terraform local workflow: create a configuration, format it, initialize providers, plan changes, apply them, inspect state, and destroy resources. These same CLI steps apply when working with real cloud providers, though provider-specific behavior and execution times will differ. Setup: open an empty directory in VS Code and create a file named main.tf.

1) Check Terraform version

Confirm the installed Terraform version before you begin.

$ terraform version
Terraform v1.10.5
on darwin_arm64

2) Create a minimal configuration

Add the random provider, a random_pet resource, and an output to main.tf. The random provider generates values locally and does not call external APIs. main.tf:

provider "random" {}

resource "random_pet" "name" {
  length = 2
}

output "random_pet_name" {
  value = random_pet.name.id
}

3) Format the configuration

Use terraform fmt to format all HCL files in the working directory.

$ terraform fmt

4) Initialize the working directory

terraform init initializes the working directory, downloads provider plugins, and configures the backend (if one is configured).

$ terraform init
Initializing the backend...
Initializing provider plugins...
- Finding latest version of hashicorp/random...
- Installing hashicorp/random v3.6.3...
Terraform has been successfully initialized!

After init, Terraform creates a .terraform directory with installed provider plugins. The binary layout may vary by Terraform version and OS.

The image shows a Visual Studio Code window with a file named "terraform-provider-random_v3.6.3_x5" highlighted in the Explorer. A warning indicates the file is not displayed due to unsupported text encoding, and the terminal below contains Terraform-related instructions.

The .terraform directory and provider plugin binaries are local artifacts for this working directory. They are safe to ignore in version control (add them to .gitignore).

5) Validate the configuration

terraform validate checks HCL syntax and basic semantics. Valid example:

$ terraform validate
Success! The configuration is valid.

Common validation error — undeclared reference:

# problematic output
output "random_pet_name" {
  value = random_pet.id
}

Validation error message:

$ terraform validate
Error: Reference to undeclared resource

  on main.tf line 8, in output "random_pet_name":
  value = random_pet.id

A managed resource "random_pet" "id" has not been declared in the root module.

Fix by referencing the declared instance label:

output "random_pet_name" {
  value = random_pet.name.id
}

6) Create an execution plan

Use terraform plan to preview changes without applying them.

$ terraform plan
Terraform used the selected providers to generate the following execution plan.
Resource actions are indicated with the following symbols:
  + create

Terraform will perform the following actions:

  # random_pet.name will be created
  + resource "random_pet" "name" {
      + id        = (known after apply)
      + length    = 2
      + separator = "-"
    }

Plan: 1 to add, 0 to change, 0 to destroy.

Changes to Outputs:
  + random_pet_name = (known after apply)

Save a plan to a file with -out so you can apply exactly that plan later:

$ terraform plan -out=bryan
Plan: 1 to add, 0 to change, 0 to destroy.

Saved the plan to: bryan
To perform exactly these actions, run the following command to apply:
  terraform apply "bryan"

7) Apply the configuration

terraform apply runs a planning step and then prompts to confirm the changes. Add -auto-approve to skip interactive confirmation (use carefully in automation). Interactive apply:

$ terraform apply
# Terraform will prompt "Do you want to perform these actions?" — type "yes" to proceed.

Non-interactive apply:

$ terraform apply -auto-approve

Example apply output:

random_pet.name: Creating...
random_pet.name: Creation complete after 0s [id=better-caribou]

Apply complete! Resources: 1 added, 0 changed, 0 destroyed.

Outputs:
random_pet_name = "better-caribou"

8) Update configuration: replacement vs. in-place update

Changing certain attributes may force a resource replacement depending on the provider and resource type. For example, changing length:

resource "random_pet" "name" {
  length = 3
}

terraform plan may show a replacement:

Terraform will perform the following actions:

  # random_pet.name must be replaced
-/+ resource "random_pet" "name" {
    id     = "better-caribou" -> (known after apply)
    length = 2 -> 3 # forces replacement
    # (1 unchanged attribute hidden)
  }

Plan: 1 to add, 0 to change, 1 to destroy.

Changes to Outputs:
  ~ random_pet_name = "better-caribou" -> (known after apply)

Apply the replacement (example with auto-approve):

$ terraform apply -auto-approve

Sample replacement output:

random_pet.name: Destroying... [id=better-caribou]
random_pet.name: Destruction complete after 0s
random_pet.name: Creating...
random_pet.name: Creation complete after 0s [id=painfully-rich-mongrel]

Apply complete! Resources: 1 added, 0 changed, 1 destroyed.

Outputs:
random_pet_name = "painfully-rich-mongrel"

Note: whether an attribute change forces replacement depends on the provider and resource.

9) Inspect the state

Terraform stores a state file (by default terraform.tfstate) that records managed resources and outputs. Example state fragment:

{
  "version": 4,
  "terraform_version": "1.10.5",
  "serial": 5,
  "lineage": "8072588f-d48c-1b42-13df2b07cae7",
  "outputs": {
    "random_pet_name": {
      "value": "painfully-rich-mongrel",
      "type": "string"
    }
  }
}

List resources tracked in state:

$ terraform state list
random_pet.name

10) Manage multiple resources

Every resource instance requires a unique label:

resource "random_pet" "bryans_pet" {
  length = 3
}

resource "random_pet" "name" {
  length = 3
}

After terraform apply:

$ terraform state list
random_pet.bryans_pet
random_pet.name

11) Destroy resources

terraform destroy plans and prompts to destroy all managed resources in the configuration. Interactive:

$ terraform destroy
# Terraform will prompt: "Do you really want to destroy all resources? ... Only 'yes' will be accepted to confirm."

Non-interactive:

$ terraform destroy --auto-approve

Example destroy output:

random_pet.name: Destroying... [id=heavily-happy-narwhal]
random_pet.name: Destruction complete after 0s

Destroy complete! Resources: 1 destroyed.

Common typo to avoid: terraform destory (incorrect). Use terraform destroy.

Be careful with -auto-approve or --auto-approve flags on apply and destroy. They bypass interactive confirmation and can cause destructive changes if used accidentally.

Quick reference — common Terraform CLI commands

Command	Purpose	Example / Notes
`terraform version`	Show Terraform version	`terraform version`
`terraform fmt`	Format HCL files	`terraform fmt`
`terraform init`	Initialize working directory & download providers	`terraform init`
`terraform validate`	Validate configuration syntax and semantics	`terraform validate`
`terraform plan`	Preview changes	`terraform plan`
`terraform plan -out=FILENAME`	Save a plan to a file to apply later	`terraform plan -out=bryan`
`terraform apply`	Apply changes (prompts for confirmation)	`terraform apply` or `terraform apply -auto-approve`
`terraform state list`	List resources tracked in state	`terraform state list`
`terraform destroy`	Destroy all managed resources	`terraform destroy` or `terraform destroy --auto-approve`

Summary

This lesson demonstrated a simple end-to-end Terraform workflow with the random provider: create a configuration, format and validate it, initialize providers, plan and apply changes, inspect state, and destroy resources. The same CLI workflow applies to cloud providers; expect provider-specific behavior and longer apply/destroy durations when interacting with remote APIs.

Links and references

Watch Video

Introduction to the Terraform CLI

Making the Most of the Terraform CLI

Course Introduction

Preparing Your Environment

Terraform Foundations

The Core Terraform Workflow

Terraform CLI

Terraform File Structure and Organization

Terraform Configuration - Fundamentals

Understading and Managing Terraform State

Marking Code Reusable

Refactoring Terraform State

Terraform Modules

Securing Terraform Configurations

Terraform Troubleshooting

HCP Terraform

Demo Terraform CLI

1) Check Terraform version

2) Create a minimal configuration

3) Format the configuration

4) Initialize the working directory

5) Validate the configuration

6) Create an execution plan

7) Apply the configuration

8) Update configuration: replacement vs. in-place update

9) Inspect the state

10) Manage multiple resources

11) Destroy resources

Quick reference — common Terraform CLI commands

Summary

Links and references

Watch Video

​1) Check Terraform version

​2) Create a minimal configuration

​3) Format the configuration

​4) Initialize the working directory

​5) Validate the configuration

​6) Create an execution plan

​7) Apply the configuration

​8) Update configuration: replacement vs. in-place update

​9) Inspect the state

​10) Manage multiple resources

​11) Destroy resources

​Quick reference — common Terraform CLI commands

​Summary

​Links and references

Watch Video

1) Check Terraform version

2) Create a minimal configuration

3) Format the configuration

4) Initialize the working directory

5) Validate the configuration

6) Create an execution plan

7) Apply the configuration

8) Update configuration: replacement vs. in-place update

9) Inspect the state

10) Manage multiple resources

11) Destroy resources

Quick reference — common Terraform CLI commands

Summary

Links and references