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Terraform-Cheatsheet.md

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Terraform Cheatsheet

Table of Contents

1. Help, Version

Get the general help for Terraform

terraform -help

Get the 'fmt' help for Terraform

terraform fmt -help

Get the Terraform version

terraform version

2. Formatting

Format your Terraform configuration files using the HCL language standard

terraform fmt

Format files in subdirectories

terraform fmt --recursive

Display differences between original configuration files and formatting changes

terraform fmt --diff

Format Check (If files are formatted correctly, the exit status will be zero)

terraform fmt --check

3. Initialization

Terraform Init Command (performs Backend Initialization, Child Module Installation, and Plugin Installation)

terraform init

Initialize the working directory, do not download plugins

terraform init -get-plugins=false

Initialize the working directory, don’t hold a state lock during backend migration

terraform init -lock=false

Initialize the working directory, and disable interactive prompts

terraform init -input=false

Reconfigure a backend, and attempt to migrate any existing state

terraform init -migrate-state

Initialize the working directory, do not verify plugins for Hashicorp signature

terraform init -verify-plugins=false

4. Download and Install Modules

Note this is usually not required as this is part of the terraform init command.

Download and installs modules needed for the configuration

terraform get

Check the versions of the already installed modules against the available modules and installs the newer versions if available

terraform get -update

5. Validation

Validate the configuration files in your directory and does not access any remote state or services

  • Terraform init should be run before 'validate' command.
terraform validate

To see easier the number of errors and warnings that you have

terraform validate -json

6. Plan Your Infrastructure

Plan will generate an execution plan

terraform plan

Save the plan file to a given path

  • Saved file can then be passed to the terraform apply command.
terraform plan -out=<path>

Create a plan to destroy all objects rather than the usual actions

terraform plan -destroy

7. Deploy Your Infrastructure

Create or update infrastructure depending on the configuration files

  • By default, a plan will be generated first and will need to be approved (yes/no) before it is applied.
terraform apply

Apply changes without having to interactively type ‘yes’ to the plan

  • Useful in automation CI/CD pipelines.
terraform apply -auto-approve

Provide the file generated using the terraform plan -out command

  • If provided, Terraform will take the actions in the plan without any confirmation prompts.
terraform apply <planfilename>

Do not hold a state lock during the Terraform apply operation

  • Use with caution if other engineers might run concurrent commands against the same workspace.
terraform apply -lock=false

Specify the number of operations run in parallel

terraform apply -parallelism=<n>

Pass in a variable value

terraform apply -var="environment=dev"

Pass in variables contained in a file

terraform apply -var-file="varfile.tfvars"

Apply changes only to the targeted resource

terraform apply -target="module.appgw.0"

8. Destroy Your Infrastructure

Destroy the infrastructure managed by Terraform

terraform destroy

Destroy only the targeted resource

terraform destroy -target="module.appgw.0"

Destroy the infrastructure without having to interactively type ‘yes’ to the plan

  • Useful in automation CI/CD pipelines.
terraform destroy --auto-approve

Destroy an instance of a resource created with for_each

terraform destroy -target="module.appgw.resource[\"key\"]"

9. 'Taint' or 'Untaint' Your Resources

  • Use the taint command to mark a resource as not fully functional. It will be deleted and re-created.

Taint a specified resource instance

terraform taint vm1.name

Untaint the already tainted resource instance

terraform untaint vm1.name

10. Refresh the State File

Modify the state file with updated metadata containing information on the resources being managed in Terraform

  • Will not modify your infrastructure.
terraform refresh

11. Show Your State File

Show the state file in a human-readable format

terraform show

Show the specific state file

  • If you want to read a specific state file, you can provide the path to it. If no path is provided, the current state file is shown.
terraform show <path to statefile>

12. Manipulate Your State File

Lists out all the resources that are tracked in the current state file

terraform state list

Move an item in the state

  • Move an item in the state, for example, this is useful when you need to tell Terraform that an item has been renamed, e.g. terraform state mv vm1.oldname vm1.newname
terraform state mv

Get the current state and outputs it to a local file

terraform state pull > state.tfstate

Update remote state from the local state file

terraform state push

Replace a provider, useful when switching to using a custom provider registry

terraform state replace-provider hashicorp/azurerm customproviderregistry/azurerm

Remove the specified instance from the state file

  • Useful when a resource has been manually deleted outside of Terraform
terraform state rm

Show the specified resource in the state file

terraform state show <resourcename>

13. Import Existing Infrastructure

Import Existing Infrastructure into Your Terraform State

  • Import a VM with id123 into the configuration defined in the configuration files under vm1.name
terraform import vm1.name -i id123

14. Get Provider Information

Display a tree of providers used in the configuration files and their requirements

terraform providers

15. Manage Your Workspaces

Show the name of the current workspace

terraform workspace show

List your workspaces

terraform workspace list

Select a specified workspace

terraform workspace select <workspace name>

Create a new workspace with a specified name

terraform workspace new <workspace name>

Delete a specified workspace

terraform workspace delete <workspace name>

16. View Your Outputs

List all the outputs currently held in your state file

  • These are displayed by default at the end of a terraform apply, this command can be useful if you want to view them independently.
terraform output

List the outputs held in the specified state file

  • '-state' option is ignored when the remote state is used.
terraform output -state=<path to state file>

List the outputs held in your state file in JSON format to make them machine-readable

terraform output -json

List a specific output held in your state file

terraform output vm1_public_ip

17. Release a Lock on Your Workspace

Remove the lock with the specified lock ID from your workspace

  • Useful when a lock has become ‘stuck’, usually after an incomplete Terraform run.
terraform force-unlock <lock_id>

18. Log In and Out to a Remote Host (Terraform Cloud)

Grab an API token for Terraform cloud (app.terraform.io) using your browser

terraform login

Log in to a specified host

terraform login <hostname>

Remove the credentials that are stored locally after logging in, by default for Terraform Cloud (app.terraform.io)

terraform logout

Remove the credentials that are stored locally after logging in for the specified hostname

terraform logout <hostname>

19. Produce a Dependency Diagram

Produce a graph in DOT language showing the dependencies between objects in the state file

  • This can then be rendered by a program called Graphwiz (amongst others).
terraform graph

Produce a dependency graph using a specified plan file (generated using terraform plan -out=tfplan)

terraform graph -plan=tfplan

Specify the type of graph to output, either plan, plan-refresh-only, plan-destroy, or apply

terraform graph -type=plan

You can see if there are any dependency cycles between the resources

terraform graph -draw-cycles

20. Test Your Expressions

Allow testing and exploration of expressions on the interactive console using the command line

terraform console

Reference