Before and After Hooks

Before and After Hooks

Before Hooks or After Hooks are a feature of terragrunt that make it possible to define custom actions that will be called either before or after execution of the terraform command.

Here’s an example:

terraform {
  before_hook "before_hook" {
    commands     = ["apply", "plan"]
    execute      = ["echo", "Running Terraform"]
  }

  after_hook "after_hook" {
    commands     = ["apply", "plan"]
    execute      = ["echo", "Finished running Terraform"]
    run_on_error = true
  }
}

In this example configuration, whenever Terragrunt runs terraform apply or terraform plan, two things will happen:

• Before Terragrunt runs terraform, it will output Running Terraform to the console.
• After Terragrunt runs terraform, it will output Finished running Terraform, regardless of whether or not the command failed.

You can have multiple before and after hooks. Each hook will execute in the order they are defined. For example:

terraform {
  before_hook "before_hook_1" {
    commands     = ["apply", "plan"]
    execute      = ["echo", "Will run Terraform"]
  }

  before_hook "before_hook_2" {
    commands     = ["apply", "plan"]
    execute      = ["echo", "Running Terraform"]
  }
}

This configuration will cause Terragrunt to output Will run Terraform and then Running Terraform before the call to Terraform.

You can learn more about all the various configuration options supported in the reference docs for the terraform block.