Resource block syntax in Terraform - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is a resource block in Terraform?

A resource block defines a piece of infrastructure to create or manage, like a server or database. It tells Terraform what to build and how.

beginner

What are the four main parts of a Terraform resource block?

1. The keyword resource
2. The resource type (like aws_instance)
3. The resource name (a unique label you choose)
4. The configuration inside curly braces defining properties

beginner

Example:

resource "aws_instance" "web" {
  ami = "ami-123456"
  instance_type = "t2.micro"
}

What does this block do?

It tells Terraform to create an AWS server named "web" using the AMI with ID "ami-123456" and the instance type "t2.micro".

beginner

Can you have multiple resource blocks of the same type in one Terraform file?

Yes! Each resource block must have a unique name within its type, so you can create many resources of the same type by giving each a different name.

beginner

Why is it important to use meaningful names in resource blocks?

Meaningful names help you and others understand what each resource is for, making your infrastructure easier to manage and avoid confusion.

What keyword starts a resource block in Terraform?

A provider

B variable

C module

D resource

The keyword resource is used to define a resource block.

In resource "aws_s3_bucket" "mybucket" {}, what is "mybucket"?

A Resource type

B Resource name

C Provider name

D Variable name

"mybucket" is the resource name, a unique label you assign.

Which part of a resource block defines the cloud service or infrastructure type?

A Provider block

B Resource name

C Resource type

D Output block

The resource type specifies what kind of infrastructure to create, like an AWS instance or S3 bucket.

Can two resource blocks have the same resource name in the same Terraform file?

A Only if they are different types

B Yes, always

C No, names must be unique

D Only if they are in different folders

Resource names must be unique within the same resource type, so two blocks can have the same name only if they are different types.

What symbol encloses the configuration settings inside a resource block?

A Curly braces {}

B Square brackets []

C Angle brackets <>

D Parentheses ()

Curly braces {} enclose the configuration inside a resource block.

Describe the structure of a Terraform resource block and its main components.

Think about how you tell Terraform what to create and how.

Explain why unique and meaningful resource names are important in Terraform configurations.

Imagine managing many servers with confusing labels.

Practice

1. What is the correct way to start a resource block in Terraform?

easy

A. resource "aws_instance" { example }

B. resource aws_instance example { }

C. resource "example" "aws_instance" { }

D. resource "aws_instance" "example" { }

Solution

1. Step 1: Understand resource block syntax

   A resource block starts with the keyword resource, followed by the resource type in quotes, then the resource name in quotes.

2. Step 2: Match the correct syntax

   resource "aws_instance" "example" { } correctly uses resource "aws_instance" "example" { }, which matches the required syntax.

3. Final Answer:

   resource "aws_instance" "example" { } -> Option D

4. Quick Check:

   Resource block syntax = resource "type" "name" { } [OK]

Hint: Resource block always uses resource "type" "name" [OK]

Common Mistakes:

• Omitting quotes around type or name
• Swapping type and name order
• Using braces incorrectly

2. Which of the following is a valid property assignment inside a Terraform resource block?

easy

A. instance_type = t2.micro

B. instance_type => "t2.micro"

C. instance_type = "t2.micro"

D. instance_type: "t2.micro"

Solution

1. Step 1: Identify correct property syntax

   Terraform uses = to assign values, and string values must be in quotes.

2. Step 2: Check each option

   instance_type = "t2.micro" uses instance_type = "t2.micro", which is correct. instance_type = t2.micro misses quotes, B and C use invalid assignment symbols.

3. Final Answer:

   instance_type = "t2.micro" -> Option C

4. Quick Check:

   Property assignment uses = and quotes for strings [OK]

Hint: Use = and quotes for string values inside resource blocks [OK]

Common Mistakes:

• Forgetting quotes around string values
• Using colon or arrow instead of =
• Missing equal sign

3. Given this resource block snippet, what will Terraform create?

resource "aws_s3_bucket" "mybucket" {
  bucket = "my-unique-bucket-123"
  acl    = "private"
}

medium

A. An S3 bucket named "mybucket" with public access

B. An S3 bucket named "my-unique-bucket-123" with private access

C. An S3 bucket named "aws_s3_bucket" with private access

D. A storage container with default public access

Solution

1. Step 1: Identify resource type and name

   The resource type is aws_s3_bucket, and the resource name is mybucket. The bucket property sets the actual bucket name.

2. Step 2: Understand properties

   The bucket property sets the bucket's real name to "my-unique-bucket-123". The acl is set to "private", meaning no public access.

3. Final Answer:

   An S3 bucket named "my-unique-bucket-123" with private access -> Option B

4. Quick Check:

   Bucket name = property value, ACL = private [OK]

Hint: Bucket name is from bucket property, not resource name [OK]

Common Mistakes:

• Confusing resource name with actual bucket name
• Assuming default ACL is public
• Ignoring property values inside the block

4. Identify the error in this Terraform resource block:

resource "aws_instance" "web" {
  ami = "ami-123456"
  instance_type = t2.micro
}

medium

A. Missing quotes around the instance_type value

B. Resource block missing closing brace

C. Incorrect resource type name

D. Missing resource name

Solution

1. Step 1: Check property value syntax

   The instance_type property value t2.micro is missing quotes, which is required for string values.

2. Step 2: Verify block structure

   The resource block has correct braces and resource type/name, so no errors there.

3. Final Answer:

   Missing quotes around the instance_type value -> Option A

4. Quick Check:

   String values must be quoted [OK]

Hint: Always quote string values inside resource blocks [OK]

Common Mistakes:

• Forgetting quotes around string properties
• Assuming braces are optional
• Mixing resource type and name order

5. You want to create two AWS EC2 instances with different names but the same AMI and instance type using resource blocks. Which is the best way to write this in Terraform?

hard

A. resource "aws_instance" "web1" {
ami = "ami-abc123"
instance_type = "t2.micro"
}
resource "aws_instance" "web2" {
ami = "ami-abc123"
instance_type = "t2.micro"
}

B. resource "aws_instance" "web" {
count = 2
ami = "ami-abc123"
instance_type = "t2.micro"
}

C. resource "aws_instance" "web" {
ami = "ami-abc123"
instance_type = "t2.micro"
name = ["web1", "web2"]
}

D. resource "aws_instance" "web" {
ami = "ami-abc123"
instance_type = "t2.micro"
for_each = ["web1", "web2"]
}

Solution

1. Step 1: Understand resource naming and duplication

   Each resource block must have a unique name.

   resource "aws_instance" "web1" {
     ami = "ami-abc123"
     instance_type = "t2.micro"
   }
   resource "aws_instance" "web2" {
     ami = "ami-abc123"
     instance_type = "t2.micro"
   }

   defines two separate resources with different names.

2. Step 2: Evaluate other options

   resource "aws_instance" "web" {
     count = 2
     ami = "ami-abc123"
     instance_type = "t2.micro"
   }

   uses count but does not differentiate names.

   resource "aws_instance" "web" {
     ami = "ami-abc123"
     instance_type = "t2.micro"
     name = ["web1", "web2"]
   }

   tries to assign a list to name property, which is invalid.

   resource "aws_instance" "web" {
     ami = "ami-abc123"
     instance_type = "t2.micro"
     for_each = ["web1", "web2"]
   }

   uses for_each incorrectly without mapping names.

3. Final Answer:

   Define two separate resource blocks with unique names -> Option A

4. Quick Check:

   Unique resource names needed for multiple instances [OK]

Hint: Use separate resource blocks with unique names for multiple instances [OK]

Common Mistakes:

• Using count without unique names
• Assigning list to single property
• Misusing for_each without proper keys