Terraform Operations

Internal

• Terraform

Version

terraform version

Help

terraform --help
terraform <command> --help

Initialization

The initialization operation initializes various local settings that will be used by subsequent commands.

The command also downloads provider binaries and, if any modules are used, the module source. The command needs to be re-run if new modules are set or changed, or backend configuration changes.

terraform init

The command creates a .terraform directory, which contains a "plugins" sub-directory:

terraform init

Initializing the backend...

Initializing provider plugins...
- Checking for available provider plugins...
- Downloading plugin for provider "aws" (hashicorp/aws) 2.49.0...

The following providers do not have any version constraints in configuration,
so the latest version was installed.

To prevent automatic upgrades to new major versions that may contain breaking
changes, it is recommended to add version = "..." constraints to the
corresponding provider blocks in configuration, with the constraint strings
suggested below.

* provider.aws: version = "~> 2.49"

Terraform has been successfully initialized!

You may now begin working with Terraform. Try running "terraform plan" to see
any changes that are required for your infrastructure. All Terraform commands
should now work.

If you ever set or change modules or backend configuration for Terraform,
rerun this command to reinitialize your working directory. If you forget, other
commands will detect it and remind you to do so if necessary.

-upgrade

The -upgrade option will additionally check for any newer versions of existing modules and providers that may be available.

Configuration File Formatting

terraform fmt

Formats all .tf in the current directory. It aligns equals, etc. Formatting enables standardization.

Validation

terraform validate

Apply

https://www.terraform.io/docs/commands/apply.html

terraform apply

The output shows the execution plan, in a format similar to diff.

-/+ means the resource will be destroyed and recreated rather than update it in-place. ~ means update in-place.

An execution plan has been generated and is shown below.
Resource actions are indicated with the following symbols:
  + create

Terraform will perform the following actions:

  # aws_instance.terraform-test-01 will be created
  + resource "aws_instance" "terraform-test-01" {
      + ami                          = "ami-a6faba49dddaecfb7"
      + arn                          = (known after apply)
      + associate_public_ip_address  = (known after apply)
      + availability_zone            = (known after apply)
      + cpu_core_count               = (known after apply)
      + cpu_threads_per_core         = (known after apply)
      + get_password_data            = false
      + host_id                      = (known after apply)
      + id                           = (known after apply)
      + instance_state               = (known after apply)
      + instance_type                = "m5.4xlarge"
      + ipv6_address_count           = (known after apply)
      + ipv6_addresses               = (known after apply)
      + key_name                     = (known after apply)
      + network_interface_id         = (known after apply)
      + password_data                = (known after apply)
      + placement_group              = (known after apply)
      + primary_network_interface_id = (known after apply)
      + private_dns                  = (known after apply)
      + private_ip                   = (known after apply)
      + public_dns                   = (known after apply)
      + public_ip                    = (known after apply)
      + security_groups              = (known after apply)
      + source_dest_check            = true
      + subnet_id                    = (known after apply)
      + tenancy                      = (known after apply)
      + volume_tags                  = (known after apply)
      + vpc_security_group_ids       = (known after apply)

      + ebs_block_device {
          + delete_on_termination = (known after apply)
          + device_name           = (known after apply)
          + encrypted             = (known after apply)
          + iops                  = (known after apply)
          + kms_key_id            = (known after apply)
          + snapshot_id           = (known after apply)
          + volume_id             = (known after apply)
          + volume_size           = (known after apply)
          + volume_type           = (known after apply)
        }

      + ephemeral_block_device {
          + device_name  = (known after apply)
          + no_device    = (known after apply)
          + virtual_name = (known after apply)
        }

      + network_interface {
          + delete_on_termination = (known after apply)
          + device_index          = (known after apply)
          + network_interface_id  = (known after apply)
        }

      + root_block_device {
          + delete_on_termination = (known after apply)
          + encrypted             = (known after apply)
          + iops                  = (known after apply)
          + kms_key_id            = (known after apply)
          + volume_id             = (known after apply)
          + volume_size           = (known after apply)
          + volume_type           = (known after apply)
        }
    }

Plan: 1 to add, 0 to change, 0 to destroy.

Do you want to perform these actions?
  Terraform will perform the actions described above.
  Only 'yes' will be accepted to approve.

  Enter a value: yes

aws_instance.terraform-test-01: Creating...
aws_instance.terraform-test-01: Still creating... [10s elapsed]
aws_instance.terraform-test-01: Still creating... [20s elapsed]
aws_instance.terraform-test-01: Creation complete after 24s [id=i-afbbc2c4a789ab871]

Apply Options

-auto-approve

Skip interactive approval of plan before applying.

Show

terraform show

Shows the state. It contain interesting information obtained after installation, such as IP addresses, etc.

It also shows content of terraform.tfstate state file.

Output

Used to extract the value of an output variable from the state file.

All variables are extracted with:

terraform output

A specific variable is extracted with:

terraform output <output-var-name>

Import

Instances can be imported using their ID:

terraform import aws_instance.web i-00000000000

Destroy

https://learn.hashicorp.com/terraform/getting-started/destroy#destroy

terraform destroy

State

https://www.terraform.io/docs/commands/state/index.html

Advanced state management.

terraform state

Provider-Specific Operations

AWS Operations

Terraform AWS Operations

Logs

/tmp/terraform-log402289911