For expressions for transformation in Terraform - Practice Problems & Coding Challenges

Challenge - 5 Problems

🧠 Conceptual

intermediate

Understanding For Expressions Output

Given the Terraform expression [for i in [1, 2, 3] : i * 2], what is the resulting list?

Terraform

[for i in [1, 2, 3] : i * 2]

A [2, 4, 6]

B [1, 2, 3]

C [1, 4, 9]

D [3, 6, 9]

💡 Hint

Each element is multiplied by 2.

The for expression iterates over each element and multiplies it by 2, producing [2, 4, 6].

❓ Configuration

intermediate

Filtering with For Expressions

What is the output of this Terraform expression?
[for n in [1, 2, 3, 4] : n if n % 2 == 0]

Terraform

[for n in [1, 2, 3, 4] : n if n % 2 == 0]

A [1, 3]

B [2, 4]

C [1, 2, 3, 4]

D SyntaxError

💡 Hint

Only even numbers are included.

The for expression filters to include only numbers divisible by 2, resulting in [2, 4].

❓ Architecture

advanced

Transforming Map Values with For Expressions

Given this Terraform map:
{"a" = 1, "b" = 2, "c" = 3}
What is the output of this expression?
{for k, v in {"a" = 1, "b" = 2, "c" = 3} : k => v * v}

Terraform

{for k, v in {"a" = 1, "b" = 2, "c" = 3} : k => v * v}

A [1, 4, 9]

B {"a" = 2, "b" = 3, "c" = 4}

C {"a" = 1, "b" = 4, "c" = 9}

D SyntaxError

💡 Hint

Each value is squared, keys remain the same.

The for expression creates a new map with the same keys but squares each value.

❓ service_behavior

advanced

For Expressions with Nested Lists

What is the output of this Terraform expression?
[for sublist in [[1, 2], [3, 4]] : [for n in sublist : n * 10]]

Terraform

[for sublist in [[1, 2], [3, 4]] : [for n in sublist : n * 10]]

A [[10, 20], [30, 40]]

B [10, 20, 30, 40]

C [[1, 2], [3, 4]]

D TypeError

💡 Hint

Each inner list element is multiplied by 10.

The outer for expression iterates over sublists, and the inner one multiplies each number by 10, preserving the nested list structure.

❓ security

expert

For Expressions and Sensitive Data Handling

Consider a Terraform variable var.passwords = ["pass1", "pass2"] marked as sensitive. Which for expression correctly creates a new list masking each password with asterisks of the same length, without exposing the original passwords in logs or state?

A [for p in var.passwords : substr(p, 0, 2)]

B [for p in var.passwords : p]

C [for p in var.passwords : "*****"]

D [for p in var.passwords : "*" * length(p)]

💡 Hint

Mask length should match original password length without revealing content.

Option D creates a masked string of asterisks matching the length of each password, avoiding exposure of actual passwords. Option D exposes passwords directly. Option D uses fixed length masking which may reveal length info incorrectly. Option D exposes part of the password.