The Common Used Terraform Commands Cheatsheet

Terraform is one of the popular infrastructure as code (IAC) tools that commonly use in the industry, this is because of the easy to learn and easy to understand HashiCorp Configuration Language (HCL) which make it so popular.

Terraform came onto the scene in 2014 to orchestrate infrastructure as code. It first targeted AWS but has grown to play nicely with large ecosystem of modules, including Google Cloud Platform (GCP), Microsoft Azure, Oracle Cloud Infrastructure, Alibaba Cloud and so on. In fact, multi-provider support is one of the main selling points of Terraform.

When learning a new language or tools that’s one major problem always come to mind, which you may need to remember or familiar your self with the command and syntax that work for the tools, the following are some list of the commonly use command lines that may help you to kick start with Terraform

Terraform Command Line

Terraform CLI tricks

terraform -install-autocomplete

Setup tab auto-completion, required logging back in

Format and Validate Terraform code

terraform fmt    # format code per HCL canonical standard
terraform validate    # validate code for syntax
terraform validate -backend=false    # validate code skip backend validation

Plan, Deploy and Cleanup Infrastructure

terraform apply --auto-approve    # apply changes without being prompted to enter “yes”
terraform destroy --auto-approve     # destroy/cleanup deployment without being prompted for “yes”
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 plan -destroy    # outputs a destroy plan 
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 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
terraform refresh    # reconcile the state in Terraform state file with real-world resources
terraform providers    # get information about providers used in current configuration

Terraform Workspaces

terraform workspace new mynewworkspace    # create a new workspace
terraform workspace select default    # change to the selected workspace
terraform workspace list    # list out all workspaces

Terraform State Manipulation

terraform state show aws_instance.my_ec2     # show details stored in Terraform state for the resource
terraform state pull > terraform.tfstate     # download and output terraform state to a file
terraform state mv aws_iam_role.my_ssm_role module.custom_module    # move a resource tracked via state to different module
terraform state replace-provider hashicorp/aws    # replace an existing provider with another
terraform state list    # list out all the resources tracked via the current state file
terraform state rm  aws_instance.myinstace    # unmanage a resource, delete it from Terraform state file

Terraform Import And Outputs

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 Miscelleneous commands

terraform version    # display Terraform binary version, also warns if version is old
terraform get -update=true    # download and update modules in the “root” module.

Terraform Console(Test out Terraform interpolations)

echo 'join(",",["foo","bar"])' | terraform console    # echo an expression into terraform console and see its expected result as output
echo '1 + 5' | terraform console    # Terraform console also has an interactive CLI just enter “terraform console”
echo "aws_instance.my_ec2.public_ip" | terraform console    # display the Public IP against the “my_ec2” Terraform resource as seen in the Terraform state file

Terraform Graph(Dependency Graphing)

terraform graph | dot -Tpng > graph.png    # produce a PNG diagrams showing relationship and dependencies between Terraform resource in your configuration/code

Terraform Cloud

terraform login    # obtain and save API token for Terraform cloud
terraform logout    # Log out of Terraform Cloud, defaults to hostname

This is only most of the command that you may used daily if you are working on Terraform, there are much more command you will be learn after you getting more familiar with Terraform.

Hope the list will help

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