Module outputs in Terraform - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to output the module's instance ID.

Terraform

output "instance_id" {
  value = module.web_server.[1]
}

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

Aid

Binstance_id

Cinstance

Dserver_id

Attempts:

3 left

💡 Hint

Common Mistakes

Using incorrect attribute names like 'instance' or 'server_id'.

Confusing module name with output name.

The module's output value is accessed by its name. Here, the correct output attribute is id.

2fill in blank

medium

Complete the code to define an output that shows the module's public IP.

Terraform

output "public_ip" {
  value = module.network.[1]
}

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

Aip_address

Bpublic_ip

Cip

Daddress

Attempts:

3 left

💡 Hint

Common Mistakes

Using generic names like 'ip' or 'address' that may not exist.

Assuming the output name without checking the module.

The module must have an output named public_ip to expose the public IP address.

3fill in blank

hard

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

Terraform

output "subnet_id" {
  value = module.vpc.[1]
}

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

Asubnet

BsubnetId

CsubnetID

Dsubnet_id

Attempts:

3 left

💡 Hint

Common Mistakes

Using camelCase or PascalCase instead of snake_case.

Guessing output names without verifying.

Terraform output names are case-sensitive and usually use snake_case. The correct attribute is subnet_id.

4fill in blank

hard

Fill both blanks to output the module's database endpoint and port.

Terraform

output "db_connection" {
  value = "${module.database.[1]:${module.database.[2]"
}

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

Aendpoint

Bport

Chost

Daddress

Attempts:

3 left

💡 Hint

Common Mistakes

Mixing up host and port names.

Using incorrect output names like 'address' or 'host' if not defined.

The database endpoint is usually named endpoint and the port is port in module outputs.

5fill in blank

hard

Fill all three blanks to output a formatted string with module's name, instance ID, and availability zone.

Terraform

output "instance_info" {
  value = "Name: ${module.app.[1], ID: ${module.app.[2], AZ: ${module.app.[3]"
}

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

Aname

Binstance_id

Cavailability_zone

Did

Attempts:

3 left

💡 Hint

Common Mistakes

Confusing instance_id with id.

Using incorrect output names or wrong casing.

The module outputs the instance name as name, the instance ID as id, and the availability zone as availability_zone.

Practice

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

easy

A. To share information from inside the module to the outside

B. To define variables that the module accepts

C. To create resources inside the module

D. To delete resources after deployment

Solution

1. Step 1: Understand the role of output blocks

   Output blocks are used to expose values from a module so other parts of the Terraform configuration can use them.

2. Step 2: Differentiate outputs from variables and resources

   Variables are inputs to modules, resources create infrastructure, outputs share info outwards.

3. Final Answer:

   To share information from inside the module to the outside -> Option A

4. Quick Check:

   Outputs = share info outside module [OK]

Hint: Outputs pass info out of modules, variables bring info in [OK]

Common Mistakes:

• Confusing outputs with variables
• Thinking outputs create resources
• Assuming outputs delete resources

2. Which of the following is the correct syntax to define an output named instance_ip in a Terraform module?

easy

A. output "instance_ip" : aws_instance.example.public_ip

B. output instance_ip = aws_instance.example.public_ip

C. output "instance_ip" { value = aws_instance.example.public_ip }

D. output { instance_ip = aws_instance.example.public_ip }

Solution

1. Step 1: Recall Terraform output block syntax

   Outputs use the keyword output followed by the name in quotes, then a block with value = ....

2. Step 2: Match syntax to options

   output "instance_ip" { value = aws_instance.example.public_ip } matches the correct syntax: output "name" { value = ... }.

3. Final Answer:

   output "instance_ip" { value = aws_instance.example.public_ip } -> Option C

4. Quick Check:

   Output block = output "name" { value = ... } [OK]

Hint: Outputs need quotes and value assignment inside braces [OK]

Common Mistakes:

• Missing quotes around output name
• Using equals sign outside block
• Incorrect colon or braces placement

3. Given this module output block:

output "bucket_name" {
  value = aws_s3_bucket.my_bucket.id
}

And this root module code:

module "storage" {
  source = "./modules/s3"
}

output "name" {
  value = module.storage.bucket_name
}

What will be the value of the root module's name output after applying?

medium

A. The name of the S3 bucket resource type

B. Null because the module output is not defined

C. An error because outputs cannot be nested

D. The ID of the S3 bucket created by the module

Solution

1. Step 1: Understand module output propagation

   The module outputs the bucket's ID as bucket_name. The root module accesses it via module.storage.bucket_name.

2. Step 2: Confirm root output value

   The root output name simply passes through the module's output value, so it will be the bucket ID.

3. Final Answer:

   The ID of the S3 bucket created by the module -> Option D

4. Quick Check:

   Root output = module output value [OK]

Hint: Root outputs can reference module outputs directly [OK]

Common Mistakes:

• Thinking outputs cannot be nested or chained
• Confusing bucket ID with resource type name
• Assuming output is null if not explicitly set in root

4. You have this output block inside a module:

output "subnet_id" {
  value = aws_subnet.example
}

Why is this incorrect for outputting the subnet ID?

medium

A. The output value should reference a specific attribute, like aws_subnet.example.id

B. Output blocks cannot reference resources directly

C. The output name cannot be "subnet_id"

D. The module source path is missing

Solution

1. Step 1: Check output value correctness

   To output the subnet ID, the value must reference a specific attribute like aws_subnet.example.id, not the whole resource object.

2. Step 2: Identify correct attribute to output

   For subnet ID, use aws_subnet.example.id instead of the resource itself.

3. Final Answer:

   The output value should reference a specific attribute, like aws_subnet.example.id -> Option A

4. Quick Check:

   Output value = resource attribute, not resource object [OK]

Hint: Always output resource attributes, not whole resources [OK]

Common Mistakes:

• Outputting entire resource instead of attribute
• Wrong output block name
• Ignoring module source configuration

5. You want to create a module that outputs a list of public IPs from multiple instances it creates. Which output block correctly returns this list?

hard

A. output "public_ips" { value = aws_instance.example[0].public_ip }

B. output "public_ips" { value = [for inst in aws_instance.example : inst.public_ip] }

C. output "public_ips" { value = aws_instance.example[*].id }

D. output "public_ips" { value = aws_instance.example }

Solution

1. Step 1: Understand how to output multiple values

   When multiple instances exist, use a for-expression to collect their public IPs into a list.

2. Step 2: Match correct syntax for list output

   output "public_ips" { value = [for inst in aws_instance.example : inst.public_ip] } uses a for-expression to extract public_ip from each instance correctly.

3. Final Answer:

   output "public_ips" { value = [for inst in aws_instance.example : inst.public_ip] } -> Option B

4. Quick Check:

   Use for-expression to output lists from multiple resources [OK]

Hint: Use for-expressions to gather attributes from multiple resources [OK]

Common Mistakes:

• Outputting single attribute from multiple instances without list
• Using wrong attribute like id instead of public_ip
• Outputting entire resource object