Terraform Core Workflow & Commands

Use Terraform outside the core workflow - 14%

• 4a Describe when to use terraform import to import existing infrastructure into your Terraform state
• 4b Use terraform state to view Terraform state
• 4c Describe when to enable verbose logging and what the outcome/value is

Core Terraform workflow - 14%

• 6a Describe Terraform workflow ( Write -> Plan -> Create )
• 6b Initialize a Terraform working directory (terraform init)
• 6c Validate a Terraform configuration (terraform validate)
• 6d Generate and review an execution plan for Terraform (terraform plan)
• 6e Execute changes to infrastructure with Terraform (terraform apply)
• 6f Destroy Terraform managed infrastructure (terraform destroy)
• 6g Apply formatting and style adjustments to a configuration (terraform fmt)

Initialize your Terraform working directory

command	use
terraform init	initialize directory, pull down providers
terraform init -get-plugins=false	initialize directory, do not download plugins
terraform init -verify-plugins=false	initialize directory, do not verify plugins for Hashicorp signature

Format and Validate Terraform code

command	use
terraform fmt	format code per HCL canonical standard
terraform fmt -diff	display diffs of formatting changes
terraform fmt -check -recursive	process files in subdirectories
terraform validate	validate code for syntax
terraform validate -json	produce validation results in JSON format to allow using the validation result for tool integrations,
terraform validate -backend=false	validate code skip backend validation

Plan, Deploy and Cleanup Infrastructure

command	use
terraform plan -out plan.out	output the deployment plan to plan.out
terraform apply plan.out	use the plan.out plan file to deploy infrastructure
terraform apply --auto-approve	apply changes without being prompted to enter "yes"
terraform plan -destroy	outputs a destroy plan
terraform destroy --auto-approve	destroy/cleanup deployment without being prompted for “yes”
terraform apply -target=aws_instance.my_ec2	only apply/deploy changes to the targeted resource
terraform apply -var my_region_variable=us-east-1	pass a variable via command-line while applying a configuration
terraform apply -lock=true	lock the state file so it can't be modified by any other Terraform apply or modification action(possible only where backend allows locking)
terraform force-unlock LOCK_ID	unlock state file
terraform apply refresh=false	do not reconcile state file with real-world resources(helpful with large complex deployments for saving deployment time)
terraform apply --parallelism=5	number of simultaneous resource operations (Defualt 10)
terraform refresh	reconcile the state in Terraform state file with real-world resources
terraform providers	get information about providers used in current configuration

Terraform Import And Outputs

command	use
terraform import aws_instance.new_ec2_instance i-abcd1234	import EC2 instance with id i-abcd1234 into the Terraform resource named "new_ec2_instance" of type "aws_instance"
terraform import 'aws_instance.new_ec2_instance[0]' i-abcd1234	same as above, imports a real-world resource into an instance of Terraform resource
terraform output	list all outputs as stated in code
terraform output instance_public_ip	list out a specific declared output
terraform output -json	list all outputs in JSON format

Terraform workflow

TF workflow is 3 Steps

1. Write: write IaC
2. Plan: Preview changes before applying
3. Apply: Provision Infrastructure