ansh1103/terraform-eks-aws-provisioning

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Terraform Command Lines

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 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 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