Terraform plan for preview - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ service_behavior

intermediate

What does the Terraform plan command show?

When you run terraform plan, what is the main output you see?

A The current state of your infrastructure after applying changes.

B A detailed log of errors encountered during deployment.

C The final cost estimate of your cloud resources.

D A list of changes Terraform will make to your infrastructure without applying them.

💡 Hint

Think about what you want to see before making changes.

terraform plan previews the changes Terraform will make. It does not apply changes or show costs.

🧠 Conceptual

intermediate

Why use Terraform plan before apply?

Why is it important to run terraform plan before terraform apply?

A To speed up the deployment by skipping validation.

B To preview changes and avoid unexpected modifications to infrastructure.

C To delete all existing resources before creating new ones.

D To automatically fix errors in the configuration files.

💡 Hint

Consider safety and control over infrastructure changes.

Running terraform plan helps you see what will change, preventing surprises.

❓ Configuration

advanced

Which Terraform command previews changes without applying?

Given these commands, which one previews infrastructure changes without applying them?

A terraform plan

B terraform apply -auto-approve

C terraform destroy

D terraform init

💡 Hint

Look for the command that shows changes but does not make them.

terraform plan previews changes. apply makes changes, destroy deletes, init prepares the working directory.

❓ Architecture

advanced

What does Terraform plan use to compare infrastructure?

When running terraform plan, what two sources does Terraform compare to decide what changes to show?

A The last applied plan and the current configuration files.

B The cloud provider's billing data and the state file.

C The current state file and the desired configuration files.

D The local machine's resource usage and the cloud provider's API.

💡 Hint

Think about what Terraform knows and what you want it to do.

Terraform compares the saved state (what exists) with the configuration (what you want) to plan changes.

❓ security

expert

What security risk can occur if you skip Terraform plan?

If you skip running terraform plan and directly run terraform apply, what security risk might you face?

A Unintended deletion or exposure of sensitive resources without review.

B Automatic encryption of all data without user consent.

C Terraform will disable all security groups by default.

D Your credentials will be logged in plain text in the state file.

💡 Hint

Consider what happens if changes are applied without preview.

Skipping plan can cause unexpected changes like deleting or exposing resources, risking security.

Practice

1. What is the main purpose of the terraform plan command?

easy

A. To destroy all existing infrastructure

B. To apply changes directly to cloud resources

C. To initialize the Terraform working directory

D. To preview changes Terraform will make without applying them

Solution

1. Step 1: Understand the role of terraform plan

   This command shows what changes Terraform will make but does not apply them.

2. Step 2: Compare with other commands

   terraform apply applies changes, terraform destroy removes resources, and terraform init initializes the directory.

3. Final Answer:

   To preview changes Terraform will make without applying them -> Option D

4. Quick Check:

   Preview changes = terraform plan [OK]

Hint: Plan previews changes, apply makes changes [OK]

Common Mistakes:

• Confusing plan with apply
• Thinking plan modifies resources
• Mixing plan with init or destroy

2. Which of the following is the correct syntax to run a Terraform plan with a specific variable file named vars.tfvars?

easy

A. terraform plan --vars-file=vars.tfvars

B. terraform plan --varfile vars.tfvars

C. terraform plan -var-file=vars.tfvars

D. terraform plan -varfile=vars.tfvars

Solution

1. Step 1: Recall correct flag for variable files

   The correct flag is -var-file with a hyphen between var and file.

2. Step 2: Check syntax correctness

   terraform plan -var-file=vars.tfvars uses -var-file=vars.tfvars, which is the official syntax. Other options use incorrect flags.

3. Final Answer:

   terraform plan -var-file=vars.tfvars -> Option C

4. Quick Check:

   Use -var-file=filename for variable files [OK]

Hint: Use -var-file=filename to specify variable files [OK]

Common Mistakes:

• Using --varfile instead of -var-file
• Mixing underscores or missing hyphens
• Using --vars-file which is invalid

3. Given this Terraform plan output snippet:

  # aws_instance.example will be created
  + resource "aws_instance" "example" {
      + ami           = "ami-123456"
      + instance_type = "t2.micro"
    }

What does the plus sign (+) before the resource indicate?

medium

A. The resource will be created

B. The resource will be destroyed

C. The resource will be updated in place

D. The resource is unchanged

Solution

1. Step 1: Understand Terraform plan symbols

   The plus sign (+) means Terraform plans to add or create the resource.

2. Step 2: Differentiate from other symbols

   Minus (-) means destroy, ~ means update, no symbol means unchanged.

3. Final Answer:

   The resource will be created -> Option A

4. Quick Check:

   Plus sign (+) = create resource [OK]

Hint: Plus (+) means create, minus (-) means destroy [OK]

Common Mistakes:

• Confusing + with update or destroy
• Ignoring symbols and guessing
• Assuming no symbol means create

4. You run terraform plan but get this error:

Error: No configuration files found!

What is the most likely cause?

medium

A. You ran the command outside the Terraform configuration directory

B. You forgot to run terraform init first

C. Your Terraform version is outdated

D. Your cloud provider credentials are missing

Solution

1. Step 1: Analyze the error message

   The error says no configuration files found, meaning Terraform can't find .tf files.

2. Step 2: Identify common causes

   This usually happens if you run the command outside the folder containing Terraform files.

3. Final Answer:

   You ran the command outside the Terraform configuration directory -> Option A

4. Quick Check:

   No config files = wrong directory [OK]

Hint: Run plan inside folder with .tf files [OK]

Common Mistakes:

• Assuming init fixes missing files
• Blaming credentials for config file errors
• Ignoring current working directory

5. You want to preview changes only for a specific resource named aws_s3_bucket.mybucket without affecting others. Which command achieves this?

hard

A. terraform plan -only=aws_s3_bucket.mybucket

B. terraform plan -target=aws_s3_bucket.mybucket

C. terraform plan --filter=aws_s3_bucket.mybucket

D. terraform plan -resource=aws_s3_bucket.mybucket

Solution

1. Step 1: Recall how to target specific resources in plan

   The -target flag limits the plan to specified resources.

2. Step 2: Verify correct flag usage

   terraform plan -target=aws_s3_bucket.mybucket uses -target=aws_s3_bucket.mybucket, which is the correct syntax. Other options are invalid flags.

3. Final Answer:

   terraform plan -target=aws_s3_bucket.mybucket -> Option B

4. Quick Check:

   Use -target to preview specific resources [OK]

Hint: Use -target=resource_name to limit plan scope [OK]

Common Mistakes:

• Using non-existent flags like -only or --filter
• Forgetting to specify resource type and name
• Assuming plan always shows all resources