Querying data with output variables

expected time	requirements
60 minutes	A computer with Terraform installed.

Goal: Learn how to get data from a provider and use it.

Explanation

Sometimes you need to “read” a detail in order to provision your code. Some example can be:

• Read an already existing VPC.
• Find all availability zones.
• Read the contents of a file.

You may want to use the found data further in your code.

# Find all images from a specified family and project.
data "google_compute_image" "my_image" {
  family  = "debian-9"
  project = "debian-cloud"
}

# Make a resource based on the found image.
resource "google_compute_instance" "default" {
  # ...

  boot_disk {
    initialize_params {
      image = data.google_compute_image.my_image.self_link
    }
  }
}

Most providers have two sides to a resource:

1. resource - To describe the resources to created.
2. data - To find resources.

Demo

Here.

Assignment

• For your cloud provider, search for “terraform data images”. (replace PROVIDER for your provider.)
• Make a new directory, write a main.tf to find the images.
• Write a file (local_file) with the images found.