sompol13/learn-terraform-expressions

Learn Terraform Expressions

In this tutorial, you will deploy a pre-generated webapp to EC2 instances behind an ELB. You will:

• use locals to assign your expressions to variables for reuse.
• use conditionals to declare if you want your configuration to contain multiple instances for high-availability.
• use the splat expression to return multiple private IPs in your network.

Name expressions with locals

• Update the network resources of your configuration and add the local.common_tags expression to your tags attribute.
• Create a new file called outputs.tf and add the values for your instance tags.
• terraform init
• terraform apply

Create a conditional for your locals criteria

Your local block accepts conditional criteria. Update your main.tf file with new criteria. If the name variable is blank, the output of the random_id resource is the tag value.

Create a conditional count criteria

Open variables.tf and add a new boolean variable for high availability.

Update your instance configuration

Open main.tf in your editor and update your aws_instance count parameter with the new conditional variable criteria.

Create a splat expression

Edit the outputs.tf file to add the new private_addresses output. This output will return the private DNS of all instances created by the aws_instance.ubuntu resource.

Reference

https://learn.hashicorp.com/tutorials/terraform/expressions