File provisioner in Terraform - Mini Project: Build & Apply

Provision a File on a Virtual Machine Using Terraform File Provisioner

📖 Scenario: You are setting up a virtual machine (VM) in the cloud. You want to place a configuration file on this VM automatically during its creation.This helps you prepare the VM with necessary settings without manual copying.

🎯 Goal: Create a Terraform configuration that provisions a file named config.txt with specific content onto the VM using the file provisioner.

📋 What You'll Learn

Define a resource for a virtual machine named example_vm.

Create a local file named config.txt with the exact content environment=production.

Use the file provisioner to copy config.txt to the VM's /tmp/config.txt path.

Ensure the provisioner is correctly attached to the example_vm resource.

💡 Why This Matters

🌍 Real World

Automating file placement on virtual machines during provisioning saves time and reduces manual errors in cloud infrastructure setup.

💼 Career

Cloud engineers and DevOps professionals often use file provisioners in Terraform to prepare VMs with necessary configuration files automatically.

1

Create a virtual machine resource named example_vm

Write a Terraform resource block for a virtual machine named example_vm using the null_resource provider as a placeholder.

Terraform

# Your code here to create a null_resource named example_vm

Hint

Use resource "null_resource" "example_vm" { } to create a simple VM placeholder.

2

Create a local file named config.txt with content environment=production

Add a Terraform local_file resource named config_file that creates a file config.txt with the content environment=production.

Terraform

resource "null_resource" "example_vm" {
}

# Your code here to create local_file resource named config_file

Hint

Use resource "local_file" "config_file" { filename = "config.txt" content = "environment=production" }.

3

Add a file provisioner to copy config.txt to the VM

Inside the example_vm resource, add a provisioner "file" block that copies the local file config.txt to the remote path /tmp/config.txt.

Terraform

resource "null_resource" "example_vm" {
  # Your code here to add file provisioner
}

resource "local_file" "config_file" {
  filename = "config.txt"
  content  = "environment=production"
}

Hint

Use provisioner "file" { source = "config.txt" destination = "/tmp/config.txt" } inside example_vm.

4

Complete the Terraform configuration with proper resource structure

Ensure the example_vm resource includes the file provisioner block exactly as specified, and the local_file resource is defined after it.

Terraform

# Verify the full resource blocks are correct
# Your code here if any final adjustments needed

Hint

Check that the provisioner is inside example_vm and local_file resource is present.

Practice

1. What is the main purpose of the file provisioner in Terraform?

easy

A. To execute shell commands on a remote server

B. To destroy resources after use

C. To create new cloud resources like virtual machines

D. To copy files from your local machine to a remote server during resource creation

Solution

1. Step 1: Understand the role of the file provisioner

   The file provisioner is designed to transfer files from your local computer to a remote machine during Terraform resource setup.

2. Step 2: Differentiate from other provisioners

   Unlike remote-exec which runs commands, file provisioner only copies files, not executes commands or manages resource lifecycle.

3. Final Answer:

   To copy files from your local machine to a remote server during resource creation -> Option D

4. Quick Check:

   File provisioner copies files = B [OK]

Hint: File provisioner = copy files to server [OK]

Common Mistakes:

• Confusing file provisioner with remote-exec
• Thinking it creates or destroys resources
• Assuming it runs commands on the server

2. Which of the following is the correct syntax to use the file provisioner in a Terraform resource block?

easy

A. provisioner file { source = "./app.conf" destination = "/etc/app.conf" }

B. provisioner "file" { source = "./app.conf" destination = "/etc/app.conf" }

C. provisioner "copy" { src = "./app.conf" dest = "/etc/app.conf" }

D. provisioner "file" { src = "./app.conf" dst = "/etc/app.conf" }

Solution

1. Step 1: Recall correct provisioner block syntax

   The provisioner block requires the provisioner type in quotes, e.g., "file", and uses source and destination keys.

2. Step 2: Identify correct attribute names

   The file provisioner uses source and destination, not src/dest or unquoted provisioner type.

3. Final Answer:

   provisioner "file" { source = "./app.conf" destination = "/etc/app.conf" } -> Option B

4. Quick Check:

   Use quotes and source/destination keys = A [OK]

Hint: Use quotes and source/destination keys for file provisioner [OK]

Common Mistakes:

• Omitting quotes around provisioner type
• Using incorrect attribute names like src/dest
• Using wrong provisioner type like "copy"

3. Given this Terraform snippet inside a resource:

provisioner "file" {
  source      = "./setup.sh"
  destination = "/tmp/setup.sh"
}
provisioner "remote-exec" {
  inline = ["chmod +x /tmp/setup.sh", "/tmp/setup.sh"]
}

What will happen after Terraform applies this resource?

medium

A. The setup.sh script is copied to /tmp and then executed with execute permission

B. The setup.sh script is copied but not executed

C. Terraform will fail because file and remote-exec cannot be used together

D. The script is executed locally but not copied to the server

Solution

1. Step 1: Understand file provisioner behavior

   The file provisioner copies the local file setup.sh to the remote path /tmp/setup.sh.

2. Step 2: Understand remote-exec provisioner behavior

   The remote-exec provisioner runs commands on the remote server, here changing permissions and executing the script.

3. Final Answer:

   The setup.sh script is copied to /tmp and then executed with execute permission -> Option A

4. Quick Check:

   File copies + remote-exec runs commands = A [OK]

Hint: File copies, remote-exec runs commands after [OK]

Common Mistakes:

• Thinking file provisioner runs commands
• Believing file and remote-exec cannot be combined
• Assuming script runs locally instead of remotely

4. You wrote this provisioner block:

provisioner "file" {
  source = "./config.yaml"
  destination = "/etc/config.yaml"
  connection {
    type     = "ssh"
    user     = "ubuntu"
    password = "mypassword"
  }
}

Terraform apply fails with a connection error. What is the most likely cause?

medium

A. The destination path must be a directory, not a file

B. The password authentication is not supported; use private_key instead

C. The connection block is inside the provisioner block, but it should be at the resource level

D. The source file path is incorrect

Solution

1. Step 1: Check connection block placement

   In Terraform, the connection block must be defined at the resource level, not inside the provisioner block.

2. Step 2: Understand connection block scope

   Placing connection inside provisioner causes Terraform to not find connection details, leading to connection errors.

3. Final Answer:

   The connection block is inside the provisioner block, but it should be at the resource level -> Option C

4. Quick Check:

   Connection block at resource level, not inside provisioner = D [OK]

Hint: Place connection block outside provisioner, inside resource [OK]

Common Mistakes:

• Putting connection block inside provisioner
• Assuming password auth is always unsupported
• Mistaking file path or destination format as cause

5. You want to copy multiple files from your local ./scripts folder to the remote server's /usr/local/bin directory using the file provisioner. Which approach is best to achieve this efficiently?

hard

A. Use a single file provisioner with source = "./scripts" and destination = "/usr/local/bin" to copy the whole folder

B. Write multiple file provisioner blocks, one for each file inside ./scripts

C. Compress the folder into a zip file, copy it with file provisioner, then unzip remotely with remote-exec

D. Use a remote-exec provisioner to download files from a public URL instead

Solution

1. Step 1: Understand file provisioner folder copying

   The file provisioner natively supports copying entire folders recursively by specifying a folder as source and a directory as destination.

2. Step 2: Differentiate efficiency of approaches

   Use a single file provisioner with source = "./scripts" and destination = "/usr/local/bin" to copy the whole folder directly copies the directory contents to /usr/local/bin efficiently without extra compression or multiple blocks.

3. Final Answer:

   Use a single file provisioner with source = "./scripts" and destination = "/usr/local/bin" to copy the whole folder -> Option A

4. Quick Check:

   File provisioner copies dir recursively = A [OK]

Hint: File provisioner copies dir recursively with source=dir destination=dir [OK]

Common Mistakes:

• Thinking file provisioner cannot copy folders recursively
• Using multiple provisioner blocks unnecessarily
• Resorting to compression when direct recursive copy works