Terraform in GitLab CI - Step-by-Step Execution

Process Flow - Terraform in GitLab CI

Start: GitLab CI Pipeline Triggered

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Checkout Code with Terraform Files

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Initialize Terraform (terraform init)

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Plan Infrastructure Changes (terraform plan)

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Apply Changes (terraform apply -auto-approve)

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Output Results (terraform output) and End Pipeline

This flow shows how GitLab CI runs Terraform commands step-by-step to manage infrastructure automatically.

Execution Sample

Terraform

stages:
  - terraform

terraform_apply:
  stage: terraform
  script:
    - terraform init
    - terraform plan
    - terraform apply -auto-approve
    - terraform output

This GitLab CI YAML runs Terraform init, plan, apply, and output commands in order to deploy infrastructure.

Process Table

Step	GitLab CI Job Action	Terraform Command	Result	Next Step
1	Checkout code	N/A	Terraform files available	terraform init
2	Initialize Terraform	terraform init	Backend and providers configured	terraform plan
3	Plan changes	terraform plan	Shows planned infrastructure changes	terraform apply
4	Apply changes	terraform apply -auto-approve	Infrastructure created/updated	Output results
5	Output results	terraform output	Outputs displayed	Pipeline ends
6	Pipeline ends	N/A	Infrastructure deployed successfully	END

💡 Pipeline ends after successful Terraform apply and output steps.

Status Tracker

Variable	Start	After Step 2	After Step 3	After Step 4	Final
Terraform Files	Not checked out	Checked out	Checked out	Checked out	Checked out
Terraform State	Empty	Initialized backend	Planned changes ready	Updated with applied changes	Updated
Infrastructure	None	None	Planned changes identified	Created/Updated	Created/Updated
Outputs	None	None	None	Generated	Displayed

Key Moments - 3 Insights

Why do we run 'terraform init' before 'terraform plan'?

'terraform init' sets up backend and providers needed for Terraform to work. Without it, 'terraform plan' cannot run properly. See execution_table step 2.

What happens if 'terraform apply' is run without '-auto-approve' in GitLab CI?

GitLab CI will wait for manual approval which blocks the pipeline. Using '-auto-approve' allows automatic apply without manual input. See execution_table step 4.

Why do we checkout code first in the pipeline?

Terraform files must be available locally to run commands. Without checkout, Terraform commands fail. See execution_table step 1.

Visual Quiz - 3 Questions

Look at the execution_table, what is the result after running 'terraform plan' at step 3?

A Backend and providers configured

B Shows planned infrastructure changes

C Infrastructure created/updated

D Outputs displayed

💡 Hint

Check the 'Result' column for step 3 in execution_table.

At which step does the GitLab CI pipeline apply infrastructure changes automatically?

A Step 4

B Step 3

C Step 2

D Step 5

💡 Hint

Look for 'terraform apply -auto-approve' in the 'Terraform Command' column.

If the 'terraform init' command fails, what will happen to the pipeline according to the flow?

A Pipeline continues to 'terraform plan'

B Pipeline skips to output results

C Pipeline stops and reports error

D Pipeline applies changes anyway

💡 Hint

Refer to the logical flow where each step depends on the previous successful step.

Concept Snapshot

Terraform in GitLab CI:
- Checkout code with Terraform files
- Run 'terraform init' to setup
- Run 'terraform plan' to preview changes
- Run 'terraform apply -auto-approve' to deploy
- Output results and finish pipeline
- Each step depends on success of previous

Full Transcript

This visual execution shows how GitLab CI automates Terraform infrastructure deployment. First, the pipeline checks out the code containing Terraform files. Then it runs 'terraform init' to configure backend and providers. Next, 'terraform plan' previews infrastructure changes. If all is good, 'terraform apply -auto-approve' deploys the changes automatically without manual approval. Finally, outputs are displayed and the pipeline ends. Each step must succeed for the next to run. This ensures safe, automated infrastructure management in GitLab CI.