File provisioner in Terraform - Step-by-Step Execution

Process Flow - File provisioner

Start Terraform Apply

↓

Create Resource (e.g., VM)

↓

Trigger File Provisioner

↓

Connect to Resource via SSH

↓

Copy Local File to Remote Path

↓

Confirm File Transfer Success

↓

Finish Provisioning

↓

Terraform Apply Complete

Terraform creates the resource, then connects via SSH to copy a local file to the remote machine before finishing.

Execution Sample

Terraform

resource "aws_instance" "example" {
  ami           = "ami-12345678"
  instance_type = "t2.micro"

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

This code creates an AWS instance and copies the local file app.conf to /tmp/app.conf on the instance.

Process Table

Step	Action	Evaluation	Result
1	Start terraform apply	N/A	Begin resource creation
2	Create aws_instance.example	AMI and instance_type valid	Instance created and running
3	Trigger file provisioner	Provisioner block found	Prepare to copy file
4	Connect via SSH to instance	SSH credentials valid	Connection established
5	Copy ./app.conf to /tmp/app.conf	Local file exists	File copied successfully
6	Confirm file presence on instance	File checksum matches	File verified
7	Finish provisioning	All provisioners successful	Terraform apply completes

💡 All steps completed successfully; file provisioner copied file and Terraform apply finished.

Status Tracker

Variable	Start	After Step 2	After Step 5	Final
aws_instance.example	undefined	created (running)	created (running)	created (running)
file provisioner status	not started	pending	file copied	completed

Key Moments - 3 Insights

Why does Terraform need SSH access for the file provisioner?

Terraform uses SSH to connect to the remote instance to copy the file, as shown in step 4 of the execution_table.

What happens if the local file does not exist?

The file provisioner fails at step 5 because it cannot find the source file to copy, stopping the apply process.

Is the file provisioner run before or after the resource is created?

It runs after the resource is created and running, as seen between steps 2 and 3 in the execution_table.

Visual Quiz - 3 Questions

Look at the execution_table, at which step is the file actually copied to the instance?

A Step 5

B Step 4

C Step 3

D Step 6

💡 Hint

Refer to the 'Action' column in execution_table row 5.

According to variable_tracker, what is the status of the file provisioner after step 5?

A pending

B file copied

C not started

D completed

💡 Hint

Check the 'file provisioner status' row after 'After Step 5' column.

If SSH credentials were invalid, at which step would the process fail?

A Step 2

B Step 5

C Step 4

D Step 6

💡 Hint

Look at the 'Connect via SSH to instance' action in execution_table step 4.

Concept Snapshot

Terraform File Provisioner:
- Runs after resource creation
- Uses SSH to connect to remote machine
- Copies local file to remote destination
- Fails if local file missing or SSH fails
- Useful for simple file transfers during provisioning

Full Transcript

The Terraform file provisioner runs after the resource is created. Terraform connects to the remote machine using SSH. It copies a local file to a specified path on the remote machine. The process verifies the file transfer. If the local file is missing or SSH connection fails, the provisioner stops the apply. This helps automate file setup on new resources.