Hello Everyone, welcome back to our blog. Today we are going to discuss some of the very cool terraform commands. These commands are very handy for day to day operations. Let’s just start our topic Terraform Commands Ultimate Cheat Sheet.
About Terraform CLI
Terraform, a tool created by HashiCorp in 2014, written in Go language, aims to build, change and version control your infrastructure. This tool have a powerful and very intuitive Command Line Interface.
Installation Cheat Sheet
Install through Curl
$ curl -O https://releases.hashicorp.com/terraform/
$ sudo unzip terraform_0.11.10_linux_amd64.zip
$ rm terraform_0.11.10_linux_amd64.zip
Install through tfenv: a Terraform version manager
First of all, download the tfenv binary and put it in your PATH.
$ git clone https://github.com/Zordrak/tfenv.git
$ echo 'export PATH="$HOME/.tfenv/bin:$PATH"'
Then, you can install desired version of terraform:
$ tfenv install 0.11.10
$ terraform --version
$ terraform init
It’s the first command you need to execute. Unless, terraform plan, apply, destroy and import will not work. Terraform init will install:
- terraform modules
- eventually a backend
- and provider(s) plugins
Init Terraform and don’t ask any input:
$ terraform init -input=false
Change backend configuration during the init:
$ terraform init -backend-config=cfg/s3.dev.tf -reconfigure
-reconfigure is used in order to tell terraform to not copy the existing state to the new remote state location.
This command is useful when you have defined some modules Modules are vendored so when you edit them, you need to get again modules content.
$ terraform get -update=true
When you use modules, the first thing you’ll have to do a terraform get. This pulls modules into the .terraform directory. Once you do that, unless you do another terraform get -update=true, you’ve essentially vendored those modules.
The plan step check configuration to execute and write a plan to apply to target infrastructure provider.
$ terraform plan -out plan.out
When you execute terraform plan command, terraform will scan all *.tf files in your directory and create the plan.
Now you have the desired state so you can execute the plan.
$ terraform apply plan.out
Apply and auto approve:
$ terraform apply -auto-approve
Apply and define new variables value:
$ terraform apply -auto-approve
Apply only one module:
$ terraform apply -target=module.s3
This -target option works with terraform plan too.
$ terraform destroy
Delete all the resources! A deletion plan can be created before:
$ terraform plan –destroy
-target option allow to destroy only one resource, for example a S3 bucket :
$ terraform destroy -target aws_s3_bucket.my_bucket
The Terraform console command is useful for testing interpolations before using them in configurations. Terraform console will read configured state even it is remote.
$ echo "aws_iam_user.notif.arn" | terraform console
$ terraform graph | dot –Tpng > graph.png
Visual dependency graph of terraform resources.
Validate command is used to validate/check the syntax of the Terraform files.
You can use a lot of providers/plugins in your terraform definition resources, so it can be useful to have a tree of providers used by modules in your project.
$ terraform providers
Pull remote state in a local copy
$ terraform state pull > terraform.tfstate
Push state in remote backend storage
terraform state push
This command is useful if for example you originally use a local tfstate and then you define a backend storage, in S3 or consul.
How to tell to Terraform you moved a resource in a module?
If you moved an existing resource in a module, you need to update
$ terraform state mv aws_iam_role.role1 module.mymodul
How to import existing resource in Terraform?
If you have an existing resource in your infrastructure provider, you can import it in your Terraform state:
$ terraform import aws_iam_policy.elastic_post
To manage multiple distinct sets of infrastructure resources/environments. Instead of create a directory for each environment to manage, we need to just create needed workspace and use them:
This command create a new workspace and then select it
$ terraform workspace new dev
Select a workspace:
$ terraform workspace select dev
$ terraform workspace list
Show current workspace:
$ terraform workspace show
Hope you will find these terraform commands handy and useful in your day to day work. This was all about our today’s topic Terraform Commands Ultimate Cheat Sheet. We will keep on adding more commands in the list. Stay Tuned.
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