• 29 Mar 2024
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Article summary

Terraform is an Infrastructure as Code tool for building, changing, and managing infrastructure in a safe, repeatable way. It is based on the configuration language called the HashiCorp Configuration Language (HCL). Operators and Infrastructure teams can use HCL to automate the deployment and management of network resources running on providers such as AWS and Azure.

For more information on Terraform, please visit the HashiCorp Learn page.

Automation Gateway (AG) contains a Terraform Module Execution Engine that supports the discovery, decoration and execution of Terraform modules.

Note: For a complete list of Terraform versions supported by Automation Gateway, see Itential Dependencies.

The AG server performs discovery of Terraform modules at startup time and maintains a cache of all managed modules in memory. Users determine the modules being managed by providing a list of directory paths in their AG properties.yml configuration file. A recursive search of the directory paths is performed.

Once a module has been discovered, it is available to be decorated. The decoration of Terraform modules within Automation Gateway is similar to that of Ansible playbooks. However, instead of decorating the variables within a playbook, users decorate the variables found in the script components within a Terraform module. The decorated variables are then passed as arguments to the APIs that execute the module. A permanent copy of each module's decoration is stored in a local database that is maintained by Automation Gateway.

A complete set of REST APIs are available for clients to manage Terraform module decoration and execution. See the API Documentation section within the Automation Gateway UI for more information.


Decorating a Terraform module involves creating metadata in JSON format that describes the variables used to execute the module. The metadata is more specifically known as a JSON schema. The example below shows the JSON schema for the variables component of a Terraform module named hello_world.

Sample Variables Component

variable "access_key" {

variable "secret_key" {

Sample Decoration

  "title": "hello_world",
  "type": "object",
  "properties": {
    "access_key": {
      "type": "string",
      "description": "AWS access key"
    "secret_key": {
      "type": "string",
      "description": "AWS secret key"
  "required": []

Terraform Commands

Below is an overview of the Terraform commands that are front-ended by the AG Terraform APIs.

Note: The state file, .tfstate is used to manage the state of the infrastructure at any point. The state file is present inside the directory containing the Terraform module on the AG Server.


The terraform init command is used to initialize a working directory containing Terraform configuration files. This is the first command that should be run after writing a new Terraform configuration or cloning an existing one from version control. It is safe to run this command multiple times.


The terraform plan command is used to create an execution plan. Terraform performs a refresh, unless explicitly disabled, and then determines what actions are necessary to achieve the desired state specified in the configuration files.

This command is a convenient way to check whether the execution plan for a set of changes matches your expectations without making any changes to real resources or to the state. For example, terraform plan might be run before committing a change to version control, to create confidence that it will behave as expected.


The terraform apply command is used to apply the changes required to reach the desired state of the configuration, or the pre-determined set of actions generated by a terraform plan execution plan.


The terraform destroy command is used to destroy the Terraform-managed infrastructure.


The terraform validate command is used to validate the configuration of a Terraform module.

Earlier Release Versions

For documentation of this feature specific to earlier release versions of IAP, click here.

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