Terraform Commands - Hands-on Learning


Terraform Commands:-

Here, we begin working with Terraform commands. We will start by creating a very simple Terraform file that will pull down the an image from Docker Hub.

List the Terraform commands:
terraform
Common commands:
apply: Builds or changes infrastructure
console: Interactive console for Terraform interpolations
destroy: Destroys Terraform-managed infrastructure
fmt: Rewrites configuration files to canonical format
get: Downloads and installs modules for the configuration
graph: Creates a visual graph of Terraform resources
import: Imports existing infrastructure into Terraform
init: Initializes a new or existing Terraform configuration
output: Reads an output from a state file
plan: Generates and shows an execution plan
providers: Prints a tree of the providers used in the configuration
push: Uploads this Terraform module to Terraform Enterprise to run
refresh: Updates local state file against real resources
show: Inspects Terraform state or plan
taint: Manually marks a resource for recreation
untaint: Manually unmarks a resource as tainted
validate: Validates the Terraform files
version: Prints the Terraform version
workspace: Workspace management

Set up the environment:

mkdir -p terraform/basics
cd terraform/basics
Create a Terraform script:

vi main.tf
main.tf contents:

# Download the latest Ghost image
resource "docker_image" "image_id" {
  name = "ghost:latest"
}
Initialize Terraform:

terraform init
Validate the Terraform file:

terraform validate
List providers in the folder:

ls .terraform/plugins/linux_amd64/
List providers used in the configuration:

terraform providers
Terraform Plan:

terraform plan
Useful flags for plan:
-out=path: Writes a plan file to the given path. This can be used as input to the "apply" command.
-var 'foo=bar': Set a variable in the Terraform configuration. This flag can be set multiple times.

Terraform Apply:

terraform apply
Useful flags for apply:
-auto-approve: This skips interactive approval of plan before applying.
-var 'foo=bar': This sets a variable in the Terraform configuration. It can be set multiple times.

Confirm your apply by typing yes. The apply will take a bit to complete.

List the Docker images:

docker image ls
Terraform Show:

terraform show
Terraform Destroy:

terraform destroy
Confirm your destroy by typing yes.

Useful flags for destroys:
-auto-approve: Skip interactive approval of plan before applying.

Re-list the Docker images:

docker image ls
Using a plan:

terraform plan -out=tfplan
Applying a plan:

terraform apply tfplan
Show the Docker Image resource:

terraform show
Destroy the resource once again:

terraform destroy
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