String functions (join, split, format) in Terraform - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ service_behavior

intermediate

What is the output of this Terraform expression using join and split?

Given the Terraform expression:

join(",", split("-", "a-b-c-d"))

What is the resulting string?

Terraform

join(",", split("-", "a-b-c-d"))

A "a,b,c,d"

B "a-b-c-d"

C "a,b-c,d"

D "a,b,c-d"

💡 Hint

Think about how split breaks the string and how join combines the list.

The split function breaks the string at each '-', producing ["a", "b", "c", "d"]. Then join combines these with commas, resulting in "a,b,c,d".

❓ Configuration

intermediate

What is the value of variable 'result' after this Terraform format call?

Consider this Terraform code:

variable "name" { default = "cloud" }
variable "count" { default = 3 }

output "result" {
  value = format("%s-%d", var.name, var.count)
}

What is the output value of 'result'?

Terraform

format("%s-%d", var.name, var.count)

A "cloud-3"

B "3-cloud"

C "cloud-"

D "%s-%d"

💡 Hint

Look at the order of arguments in format and their types.

The format function replaces %s with the string var.name ('cloud') and %d with the integer var.count (3), producing 'cloud-3'.

🧠 Conceptual

advanced

Which option correctly splits a comma-separated string into a list in Terraform?

You have a string variable:

variable "csv" { default = "red,green,blue" }

Which expression produces the list ["red", "green", "blue"]?

A format("%s", var.csv)

B join(",", var.csv)

C split(",", var.csv)

D split(";", var.csv)

💡 Hint

Splitting uses the delimiter to break the string into parts.

split(",", var.csv) breaks the string at commas, producing the list ["red", "green", "blue"].

❓ security

advanced

What is the risk of using format with user input without validation in Terraform?

If you use format("User: %s", var.user_input) directly in resource names, what could happen?

A There is no risk; format is safe for all inputs

B Terraform will automatically sanitize the input to prevent errors

C The format function will throw an error if input is unsafe

D Resource names might contain invalid characters causing deployment failure

💡 Hint

Think about what happens if user input has spaces or special symbols.

Terraform resource names must follow strict rules. If user input contains invalid characters, the resource creation will fail.

❓ Architecture

expert

Which Terraform expression produces a single string from a list with a custom separator and prefix?

Given a list variable:

variable "items" { default = ["one", "two", "three"] }

Which expression produces the string "Items: one | two | three"?

A join(" | ", format("Items: %s", var.items))

B format("Items: %s", join(" | ", var.items))

C format("Items: %s", split(" | ", var.items))

D join("Items: ", var.items)

💡 Hint

Use join to combine list elements, then format to add prefix.

join(" | ", var.items) creates "one | two | three". Then format adds "Items: " prefix, resulting in "Items: one | two | three".