basic commands and cheats for terraform

terraform_cheatsheet.md

Terraform Commands

There are a couple of commands to check the Terraform’s built-in command-line documentation:

• terraform
• terraform -h
• terraform --help

The resulting help page will have the main commands at the top, followed by the less common or more complex commands below.

We can also enter the terraform command and then a subcommand with -h or --help to pull up a list of commands that are specific to that subcommand.

Important Terraform commands:

• fmt - When we finish our Terraform configuration, we can make sure that everything is formatted correctly.
• init - The init command looks at your configuration files and determines which providers and modules it needs to pull down from the registry to allow your configuration to work properly.
• validate - Validation will catch syntax errors, version errors, and other issues.
• plan - Next, it’s always a good idea to do a dry run of your plan to see what it’s actually going to do.
• apply - This is the command that deploys or applies your configuration to a provider.
• destroy - The destroy command, obviously, will destroy your infrastructure
• output - The output command to make those defined outputs to display certain information.
• show - The show command shows the current state of a saved plan.
• state - Another good way to check your work is to use the state command.
• version - We will use the version command quite a bit to check our Terraform version,

Logging in terraform

The environment variableTF_LOG defines the log level. Valid log levels are (in order of decreasing verbosity): TRACE, DEBUG, INFO, WARN or ERROR.

• Bash
  • export TF_LOG="DEBUG"
  • export TF_LOG_PATH="tmp/terraform.log"
• PowerShell
  • $env:TF_LOG="DEBUG"
  • $env:TF_LOG_PATH="C:\tmp\terraform.log"

To set them permanently, you can add these environment variables to your .profile, .bashrc, PowerShell profile (if it exists, the path is stored in $profile environment variable) file, or the appropriate profile for your chosen shell.

Terraform CLI tricks

• terraform -install-autocomplete #Setup tab auto- completion, requires 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

Initialize your Terraform working directory

• 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

Plan, Deploy and Cleanup Infrastructure

• terraform show - to inspect current state.
• 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 workspace - shows workspaces

Terraform State Manipulation

• terraform.tfstate.backup - stores previous state
• terraform.tfstate - stores current state
• terraform state show [options] ADDRESS - shows the attributes of a single resource
• 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 registry.custom.com/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 Taint/Untaint(mark/unmark resource for recreation - > delete and then recreate)

• terraform taint aws\_instance.my\_ec2 - taints resource to be recreated on next apply
• terraform untaint aws\_instance.my\_ec2 - Remove taint from a resource
• terraform force-unlock LOCK\_ID - forcefully unlock a locked state file, LOCK_ID provided when locking the State file beforehand

Terraform Cloud

• terraform login - obtain and save API token for Terraform cloud
• terraform logout - Log out of Terraform Cloud, defaults to hostname app.terraform.io

Terraform variables precedence (low to high)

• terraform.tfvars
• terraform.tfvars.json
• *.auto.tfvars, *.auto.tfvars.json
• -var, -var-file

terraform_notes.md