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Terraform plugin commands

Incorporate a Terraform Plugin step in your pipeline to execute specific Terraform commands at designated stages. This topic provides a detailed look at the available commands within the Infrastructure as Code Management (IaCM) module.

For instance, incorporating a Terraform Provision operation automatically configures your pipeline with the terraform init, terraform plan, and terraform apply commands by default.

IaCM Supported Commands​

The supported commands include:

  • init
  • plan
  • apply
  • destroy
  • plan-destroy
  • plan-refresh-only
  • apply-refresh-only
  • detect-drift
  • validate

Terraform Plugins

Command Descriptions​

Initialize​

The terraform init command prepares a working directory containing Terraform configuration files, performing key functions like:

  • Backend Initialization: Sets up the backend for Terraform state management. Go to Terraform backend initialization for more information on how to use environment variables to initialize your infrastructure dynamically.
  • Provider Installation: Downloads and installs necessary provider plugins to interact with service provider APIs.
  • Module Installation: Downloads and sets up modules included in the configuration within the .terraform directory.

Plan​

The terraform plan creates an execution plan to preview the actions Terraform will take to align the infrastructure with the specified configuration. This includes:

  • State Refresh: Updates the state file with the latest data from the managed infrastructure.
  • Configuration Comparison: Analyzes current versus desired states to identify necessary changes.
  • Change Proposal: Lists the actions that terraform apply will execute to reach the desired state.

Harness IaCM supports resource targeting and replacement, allowing you to specify which resources to focus on during a plan operation. You can use environment variable prefixes to define these targets or replacements:

  • PLUGIN_PLAN_TARGET_
  • PLUGIN_PLAN_REPLACE_

For example, set PLUGIN_PLAN_TARGET_1=tfcode.bucket1 to target a specific resource.

Apply​

The terraform apply executes the proposed plan to modify the infrastructure state:

  • Executing Plan: Implements the changes outlined in the plan to modify resource states.
  • State Update: Updates the state file to reflect the new status of the infrastructure.

Destroy​

The terraform destroy removes all resources managed by Terraform:

  • Resource Removal: Identifies and eliminates all managed resources, respecting their interdependencies.

Plan & Destroy​

The terraform plan-destroy prepares a plan for dismantling infrastructure, outlining:

  • Destruction Overview: Highlights which resources will be removed if the plan is executed.

Plan - Refresh Only​

The plan-refresh-only command focuses on updating the state file to mirror real-time data without altering the infrastructure:

  • State Refresh: Updates the state file with the current infrastructure status.

Apply - Refresh Only​

The apply-refresh-only applies a state update without changing the infrastructure:

  • Immediate State Update: Refreshes the state file to ensure it accurately reflects the current infrastructure conditions.

Detect Drift​

Although not an official command, detect-drift is typically executed using terraform plan with specific flags to:

  • Drift Detection: Identifies discrepancies between the configured and actual states of the infrastructure.

Validate​

The terraform validate checks the configuration for errors:

  • Syntax Checks: Ensures all configuration files are syntactically correct.
  • Consistency Checks: Confirms all configurations are internally consistent with no unresolved references or missing mandatory arguments.