Resource

Summary

A resource represents a piece of real world infrastructure

Examples:

• an S3 bucket
• an EKS (Elastic Kubernetes) cluster
• a Postgres role

Example: Declaring an S3 bucket

This is how we might declare an S3 bucket. You can reference this in different components, and then everything will deploy together when running terraform apply.

resource "aws_s3_bucket" "my_bucket" {
    bucket = "my-test-bucket"
    acl = "private"
    tags = {
        Name = "My bucket"
        Environment = "Dev"
    }
}

Null Resource

A null_resource is similar to a regular resource, in that it adheres to the resource lifecycle model.

• However, it merely serves as a placeholder for executing arbitrary actions within Terraform configurations, but without actually provisioning any physical resources.
• It does not perform any further actions beyond initialization
• The default behavior of a null_resource is that it will execute only once during the first run of the terraform apply command, but this can be overridden with the triggers field.

Below is the sample code:

resource "null_resource" "example" {
  provisioner "local-exec" {
    command = "echo This command will execute only once during apply"
  }
}

If we run terraform apply on this module, we will see the echo command in the console. However, if we run it again, that same echo command will not be run.

If we want the block to run every time, we can add:

triggers = {
    always_run = timestamp()
}

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Backlinks

• Terraform