Outputs as documentation in Terraform - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to define an output that shows the instance ID.

Terraform

output "instance_id" {
  value = [1]
}

Drag options to blanks, or click blank then click option'

Aaws_instance.example.type

Baws_instance.example.name

Caws_instance.example.id

Daws_instance.example.region

Attempts:

3 left

💡 Hint

Common Mistakes

Using the instance name instead of the ID.

Using the resource type property instead of the ID.

The output value should be the instance ID, which is accessed by aws_instance.example.id.

2fill in blank

medium

Complete the code to add a description to the output.

Terraform

output "instance_ip" {
  value       = aws_instance.example.public_ip
  description = [1]
}

Drag options to blanks, or click blank then click option'

A"The public IP address of the instance"

Binstance_ip

C"Instance public IP"

DThe public IP address of the instance

Attempts:

3 left

💡 Hint

Common Mistakes

Forgetting to put quotes around the description.

Using a variable name instead of a descriptive string.

The description must be a string enclosed in quotes to document the output.

3fill in blank

hard

Fix the error in the output block to correctly reference the subnet ID.

Terraform

output "subnet_id" {
  value = aws_subnet.example[1]
}

Drag options to blanks, or click blank then click option'

A.name

B[0]

C.subnet_id

D.id

Attempts:

3 left

💡 Hint

Common Mistakes

Using .subnet_id which is not a valid attribute.

Using .name which is not the ID.

The correct attribute for the subnet ID is .id.

4fill in blank

hard

Fill both blanks to output the list of security group IDs and add a description.

Terraform

output "security_group_ids" {
  value       = aws_security_group.example[1]
  description = [2]
}

Drag options to blanks, or click blank then click option'

A.*.id

B"List of security group IDs"

C"Security groups attached"

D.id

Attempts:

3 left

💡 Hint

Common Mistakes

Using .id instead of .* .id for lists.

Not quoting the description string.

To output a list of IDs, use .*.id. The description should be a quoted string.

5fill in blank

hard

Fill all three blanks to output a map of instance names to their private IPs with a description.

Terraform

output "instance_private_ips" {
  value       = { for inst in aws_instance.example : inst[1] => inst[2] }
  description = [3]
}

Drag options to blanks, or click blank then click option'

A.tags.Name

B.private_ip

C"Mapping of instance names to private IP addresses"

D.id

Attempts:

3 left

💡 Hint

Common Mistakes

Using .id instead of .tags.Name for keys.

Not quoting the description string.

The map key is the instance name from tags, the value is the private IP, and the description is a quoted string.

Practice

1. What is the main purpose of output blocks in Terraform?

easy

A. To write resource creation logic

B. To define variables for input values

C. To display important information after infrastructure is created

D. To configure provider settings

Solution

1. Step 1: Understand output block role

   Output blocks are used to show key information after Terraform finishes applying changes.

2. Step 2: Differentiate from other blocks

   Variables define inputs, providers configure cloud access, and resources create infrastructure, so outputs are for displaying results.

3. Final Answer:

   To display important information after infrastructure is created -> Option C

4. Quick Check:

   Outputs = display info [OK]

Hint: Outputs show info after apply, not inputs or configs [OK]

Common Mistakes:

• Confusing outputs with variables
• Thinking outputs create resources
• Assuming outputs configure providers

2. Which of the following is the correct syntax to define an output with a description in Terraform?

easy

A. output ip_address { value = aws_instance.web.public_ip description = "Public IP address" }

B. output "ip_address" { value = aws_instance.web.public_ip description = "Public IP address" }

C. output "ip_address" { value = aws_instance.web.public_ip } description = "Public IP address"

D. output "ip_address" { value = aws_instance.web.public_ip desc = "Public IP address" }

Solution

1. Step 1: Check output block structure

   An output block requires a name, a value, and optionally a description inside curly braces.

2. Step 2: Verify correct syntax

   The correct syntax places each attribute on its own line or separated properly; output "ip_address" { value = aws_instance.web.public_ip description = "Public IP address" } shows the correct format with value and description.

3. Final Answer:

   output "ip_address" { value = aws_instance.web.public_ip description = "Public IP address" } -> Option B

4. Quick Check:

   Output syntax = name, value, description [OK]

Hint: Output blocks need name, value, description inside braces [OK]

Common Mistakes:

• Missing quotes around output name
• Placing description outside the block
• Using incorrect attribute names

3. Given this Terraform output block:

output "db_password" {
  value       = aws_db_instance.main.password
  sensitive   = true
  description = "The database password"
}

What will happen when you run terraform apply?

medium

A. The password will not be shown in the output because it is marked sensitive

B. Terraform will throw a syntax error due to sensitive attribute

C. The password will be shown in the output after apply

D. The password will be printed in plain text in the logs

Solution

1. Step 1: Understand sensitive attribute effect

   Marking an output as sensitive hides its value from the standard output to protect secrets.

2. Step 2: Predict terraform apply behavior

   Terraform will apply changes but will not display the sensitive value in the output summary.

3. Final Answer:

   The password will not be shown in the output because it is marked sensitive -> Option A

4. Quick Check:

   sensitive output hides value [OK]

Hint: Sensitive outputs hide values after apply [OK]

Common Mistakes:

• Assuming sensitive outputs print values
• Thinking sensitive causes errors
• Confusing sensitive with encryption

4. You wrote this output block:

output "instance_ip" {
value = aws_instance.web.public_ip
}

Terraform shows a warning about missing description. How do you fix it?

medium

A. Rename the output to "instance_ip_address"

B. Remove the output block completely

C. Change value to a string literal

D. Add a description attribute inside the output block

Solution

1. Step 1: Identify missing description

   Terraform recommends adding descriptions to outputs for clarity and documentation.

2. Step 2: Add description attribute

   Include a line like description = "Public IP of the instance" inside the output block to fix the warning.

3. Final Answer:

   Add a description attribute inside the output block -> Option D

4. Quick Check:

   Outputs need descriptions for docs [OK]

Hint: Add description attribute to output blocks [OK]

Common Mistakes:

• Ignoring description warnings
• Changing output name unnecessarily
• Removing output instead of fixing

5. You want to output a list of public IPs from multiple instances created with a for_each in Terraform. Which output block correctly documents and outputs this list?

hard

A. output "instance_ips" {
value = [for inst in aws_instance.web : inst.public_ip]
description = "List of public IPs for all web instances"
}

B. output "instance_ips" {
value = aws_instance.web.public_ip
description = "List of public IPs for all web instances"
}

C. output "instance_ips" {
value = tolist(aws_instance.web.public_ip)
description = "List of public IPs for all web instances"
}

D. output "instance_ips" {
value = aws_instance.web.public_ip[0]
description = "List of public IPs for all web instances"
}

Solution

1. Step 1: Understand for_each resource outputs

   When using for_each, resources are a map, so to get all public IPs, a for expression is needed to collect them.

2. Step 2: Check output value expression

   output "instance_ips" { value = [for inst in aws_instance.web : inst.public_ip] description = "List of public IPs for all web instances" } uses a for expression to iterate over all instances and extract public_ip, which is correct and documented with description.

3. Final Answer:

   output "instance_ips" { value = [for inst in aws_instance.web : inst.public_ip] description = "List of public IPs for all web instances" } -> Option A

4. Quick Check:

   Use for expression to output list from for_each [OK]

Hint: Use for expression to collect values from for_each resources [OK]

Common Mistakes:

• Using direct attribute without iteration
• Accessing only first element
• Using incorrect syntax for list extraction