Splat expressions in Terraform - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is a splat expression in Terraform?

A splat expression lets you get a list of values from multiple resources or attributes easily, like collecting all names from a group of servers.

beginner

How does the syntax resource_type.resource_name[*].attribute work in Terraform?

It collects the attribute from all instances of resource_name and returns a list of those values.

beginner

Why use splat expressions instead of accessing each resource attribute individually?

Splat expressions save time and code by automatically gathering values from many resources without writing repetitive code.

intermediate

What is the difference between resource[*].attribute and resource.attribute in Terraform?

resource[*].attribute returns a list of attributes from all resources, while resource.attribute accesses a single resource's attribute.

intermediate

Can splat expressions be used with nested attributes in Terraform? Give an example.

Yes, for example aws_instance.example[*].tags["Name"] collects the 'Name' tag from all instances.

What does the splat expression aws_instance.web[*].id return?

A A list of IDs for all aws_instance.web resources

B The ID of the first aws_instance.web resource

C A single string with all IDs concatenated

D An error because splat expressions are invalid

The splat expression collects the 'id' attribute from all 'aws_instance.web' resources and returns them as a list.

Which symbol is used in Terraform splat expressions to select all instances?

A *

B #

C @

D &

The asterisk (*) is used to select all instances in a splat expression.

If you want to get a list of all public IPs from multiple instances, which expression is correct?

A aws_instance.example.public_ip

B aws_instance.example[*].public_ip

C aws_instance.example[0].public_ip

D aws_instance.example.public_ip[*]

Using the splat expression with [*] collects the 'public_ip' from all instances.

What type of value does a splat expression return in Terraform?

A Map

B String

C Boolean

D List

Splat expressions return a list of values collected from multiple resources or attributes.

Can splat expressions be used with resources created using count or for_each?

A Only with for_each, not with count

B No, splat expressions only work with single resources

C Yes, they work well to gather attributes from all instances

D Only with count, not with for_each

Splat expressions are designed to work with multiple instances created by count or for_each.

Explain what a splat expression is in Terraform and how it helps when working with multiple resources.

Think about how you would get the same attribute from many servers without writing code for each one.

Describe the syntax of a splat expression and give an example of how to get all instance IDs from a resource.

Use the * symbol inside square brackets to select all instances.