Count vs for_each decision in Terraform - Quick Revision & Key Differences

Recall & Review

beginner

What is the main difference between count and for_each in Terraform?

count creates multiple instances based on a number, while for_each creates instances based on each item in a map or set.

beginner

When should you prefer for_each over count?

Use for_each when you want to create resources with unique keys or names, especially when working with maps or sets.

beginner

Can count be used with maps or sets directly?

No, count only accepts a number. To use maps or sets, for_each is required.

intermediate

How does resource addressing differ between count and for_each?

count uses numeric indexes (e.g., resource[0]), while for_each uses keys from the map or set (e.g., resource["key"]).

intermediate

What is a common pitfall when using count with conditional expressions?

Changing count dynamically can cause resource replacement because indexes shift, leading to unexpected resource destruction and recreation.

Which Terraform argument allows creating resources based on keys from a map or set?

A for_each

B count

C depends_on

D lifecycle

for_each iterates over maps or sets to create resources with unique keys.

What type of value does count accept?

A Number

B Map

C Set

D List

count requires a numeric value to specify how many instances to create.

If you want to create three identical resources, which is simpler to use?

A for_each with a map of three keys

B count = 3

C depends_on

D provider block

count is simpler for creating multiple identical resources by number.

What happens if you change the order of items in a for_each map?

A Terraform throws an error

B Resources get replaced due to index shift

C Resources keep their keys and do not get replaced

D Resources are duplicated

for_each uses keys, so order changes do not cause resource replacement.

Which method is better for resources that need unique names or identifiers?

A depends_on

B count

C variable

D for_each

for_each allows assigning unique keys, making it better for unique resource names.

Explain when and why you would choose count versus for_each in Terraform.

Think about whether you need unique keys or just a number of copies.

Describe how resource addressing differs between count and for_each and why this matters.

Consider how Terraform tracks each resource instance.