Output declaration syntax in Terraform - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to declare an output named "instance_ip".

Terraform

output "instance_ip" {
  value = [1]
}

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

Aaws_instance.example.arn

Baws_instance.example.private_ip

Caws_instance.example.public_ip

Daws_instance.example.id

Attempts:

3 left

💡 Hint

Common Mistakes

Using private_ip instead of public_ip when external access is needed.

Using resource id or arn which are not IP addresses.

The output value should be the public IP of the instance to expose it.

2fill in blank

medium

Complete the code to declare an output named "bucket_name" that shows the S3 bucket's name.

Terraform

output "bucket_name" {
  value = [1]
}

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

Aaws_s3_bucket.mybucket.arn

Baws_s3_bucket.mybucket.bucket

Caws_s3_bucket.mybucket.region

Daws_s3_bucket.mybucket.id

Attempts:

3 left

💡 Hint

Common Mistakes

Using arn or id instead of the bucket name.

Using region which is unrelated to the bucket's name.

The bucket attribute "bucket" holds the bucket's name, which is what we want to output.

3fill in blank

hard

Fix the error in the output declaration to correctly output the instance's ID.

Terraform

output "instance_id" {
  value = aws_instance.example.[1]
}

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

Ainstance

Binstance_id

Cip_address

Did

Attempts:

3 left

💡 Hint

Common Mistakes

Using "instance_id" which is not a valid attribute.

Using "instance" which is the resource name, not an attribute.

The correct attribute to get the instance ID is "id".

4fill in blank

hard

Fill both blanks to declare an output named "db_endpoint" that outputs the database endpoint address.

Terraform

output "db_endpoint" {
  value = [1].[2]
}

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

Aaws_db_instance.mydb

Baws_db_instance.db

Cendpoint

Daddress

Attempts:

3 left

💡 Hint

Common Mistakes

Using wrong resource name like "db" instead of "mydb".

Using "endpoint" attribute which is not valid; use "address".

The resource is "aws_db_instance.mydb" and the attribute for the endpoint address is "address".

5fill in blank

hard

Fill all three blanks to declare an output named "web_url" that outputs the URL combining protocol and instance public IP.

Terraform

output "web_url" {
  value = "http://" + [1].[2] + ":[3]"
}

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

Aaws_instance.web

Bpublic_ip

C80

Dprivate_ip

Attempts:

3 left

💡 Hint

Common Mistakes

Using private_ip instead of public_ip which is not accessible externally.

Using wrong port number or missing port.

The output combines "http://" with the instance's public IP and port 80.

Practice

1. What is the purpose of an output block in a Terraform configuration?

easy

A. To display useful information after Terraform applies changes

B. To define variables for input values

C. To create resources in the cloud

D. To delete resources automatically

Solution

1. Step 1: Understand Terraform output blocks

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

2. Step 2: Differentiate from other blocks

   Variables define inputs, resources create cloud items, and outputs only display results.

3. Final Answer:

   To display useful information after Terraform applies changes -> Option A

4. Quick Check:

   Output block = display info [OK]

Hint: Outputs show info after apply, not inputs or resource creation [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 declare an output named instance_ip with value aws_instance.web.private_ip?

easy

A. output "instance_ip" { value = aws_instance.web.private_ip }

B. output instance_ip = aws_instance.web.private_ip

C. output "instance_ip" : aws_instance.web.private_ip

D. output instance_ip { value: aws_instance.web.private_ip }

Solution

1. Step 1: Recall Terraform output block syntax

   The correct syntax uses the keyword output, a quoted name, and a block with value assignment using =.

2. Step 2: Check each option

   output "instance_ip" { value = aws_instance.web.private_ip } matches the correct syntax exactly. Others use invalid assignment or missing quotes.

3. Final Answer:

   output "instance_ip" { value = aws_instance.web.private_ip } -> Option A

4. Quick Check:

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

Hint: Output name must be quoted and value assigned with = inside braces [OK]

Common Mistakes:

• Omitting quotes around output name
• Using = outside braces
• Using colon instead of =

3. Given this output block:

output "db_password" {
  value     = var.db_password
  sensitive = true
}

What will Terraform do when you run terraform apply?

medium

A. Cause a syntax error because sensitive is not allowed

B. Show the db_password value in the output after apply

C. Hide the db_password value in the output to keep it secret

D. Ignore the output block completely

Solution

1. Step 1: Understand the sensitive attribute

   Setting sensitive = true tells Terraform to hide the output value from the terminal to protect secrets.

2. Step 2: Predict Terraform behavior on apply

   Terraform will not display the actual value but will note that a sensitive output exists.

3. Final Answer:

   Hide the db_password value in the output to keep it secret -> Option C

4. Quick Check:

   sensitive = true hides output value [OK]

Hint: Sensitive outputs hide values after apply to protect secrets [OK]

Common Mistakes:

• Expecting sensitive outputs to show values
• Thinking sensitive causes errors
• Assuming outputs are ignored

4. Identify the error in this output block:

output "server_port" {
  value = 8080
  sensitive = "false"
}

medium

A. The value 8080 must be a string, not a number

B. The sensitive attribute should be a boolean, not a string

C. Output names cannot be quoted

D. Missing a comma after the value line

Solution

1. Step 1: Check attribute types in output block

   The sensitive attribute expects a boolean (true or false), not a string in quotes.

2. Step 2: Validate other parts

   Value can be a number without quotes, output names must be quoted, and commas are not used between lines in HCL.

3. Final Answer:

   The sensitive attribute should be a boolean, not a string -> Option B

4. Quick Check:

   sensitive = true/false boolean, not "false" string [OK]

Hint: Boolean attributes must not be quoted strings [OK]

Common Mistakes:

• Using quotes around boolean values
• Thinking output names are unquoted
• Adding commas between lines

5. You want to output a list of public IPs from multiple AWS instances stored in aws_instance.web list. Which output block correctly returns their public IPs?

hard

A. output "public_ips" { value = for i in aws_instance.web { i.public_ip } }

B. output "public_ips" { value = aws_instance.web.public_ip }

C. output "public_ips" { value = aws_instance.web.public_ip[*] }

D. output "public_ips" { value = [for i in aws_instance.web : i.public_ip] }

Solution

1. Step 1: Understand how to extract values from a list of resources

   Terraform uses for-expressions inside output value to map over lists and extract attributes.

2. Step 2: Evaluate each option

   output "public_ips" { value = [for i in aws_instance.web : i.public_ip] } uses correct for-expression syntax. output "public_ips" { value = aws_instance.web.public_ip } tries direct attribute access on list (invalid). output "public_ips" { value = aws_instance.web.public_ip[*] } uses incorrect splat syntax. output "public_ips" { value = for i in aws_instance.web { i.public_ip } } has invalid block syntax.

3. Final Answer:

   output "public_ips" { value = [for i in aws_instance.web : i.public_ip] } -> Option D

4. Quick Check:

   Use for-expressions to map list attributes [OK]

Hint: Use for-expressions with [for x in list : x.attr] to extract lists [OK]

Common Mistakes:

• Trying to access attribute directly on list
• Using invalid syntax for list comprehension
• Confusing for-expression with block syntax