Terraform integration in merge requests

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Collaborating around Infrastructure as Code (IaC) changes requires both code changes and expected infrastructure changes to be checked and approved. GitLab provides a solution to help collaboration around Terraform code changes and their expected effects using the merge request pages. This way users don't have to build custom tools or rely on 3rd party solutions to streamline their IaC workflows.

Output Terraform Plan information into a merge request

Using the GitLab Terraform Report artifact, you can expose details from terraform plan runs directly into a merge request widget, enabling you to see statistics about the resources that Terraform creates, modifies, or destroys.

WARNING: Like any other job artifact, Terraform plan data is viewable by anyone with the Guest role on the repository. Neither Terraform nor GitLab encrypts the plan file by default. If your Terraform plan.json or plan.cache files include sensitive data like passwords, access tokens, or certificates, you should encrypt the plan output or modify the project visibility settings. You should also disable public pipelines and set the artifact's public flag to false (public: false). This setting ensures artifacts are accessible only to GitLab administrators and project members with at least the Reporter role.

Configure Terraform report artifacts

GitLab integrates with Terraform and OpenTofu through CI/CD templates and components that use GitLab-managed Terraform state and display Terraform changes on merge requests.

Automatically configure Terraform report artifacts

You should use either the Terraform CI/CD templates or the OpenTofu CI/CD component, which automatically configure the Terraform report artifacts in the plan jobs.

Manually configure Terraform report artifacts

For a quick setup, you should customize the pre-built image and rely on the gitlab-terraform and gitlab-tofu helpers.

To manually configure a GitLab Terraform Report artifact:

For simplicity, let's define a few reusable variables to allow us to refer to these files multiple times:
```
variables:
  PLAN: plan.cache
  PLAN_JSON: plan.json
```
Install jq, a lightweight and flexible command-line JSON processor.

Create an alias for a specific jq command that parses out the information we want to extract from the terraform plan output:

before_script:
  - apk --no-cache add jq
  - alias convert_report="jq -r '([.resource_changes[]?.change.actions?]|flatten)|{\"create\":(map(select(.==\"create\"))|length),\"update\":(map(select(.==\"update\"))|length),\"delete\":(map(select(.==\"delete\"))|length)}'"

NOTE: In distributions that use Bash (for example, Ubuntu), alias statements are not expanded in non-interactive mode. If your pipelines fail with the error convert_report: command not found, alias expansion can be activated explicitly by adding a shopt command to your script:

before_script:
  - shopt -s expand_aliases
  - alias convert_report="jq -r '([.resource_changes[]?.change.actions?]|flatten)|{\"create\":(map(select(.==\"create\"))|length),\"update\":(map(select(.==\"update\"))|length),\"delete\":(map(select(.==\"delete\"))|length)}'"

Define a script that runs terraform plan and terraform show. These commands pipe the output and convert the relevant bits into a store variable PLAN_JSON. This JSON is used to create a GitLab Terraform Report artifact. The Terraform report obtains a Terraform tfplan.json file. The collected Terraform plan report is uploaded to GitLab as an artifact, and is shown in merge requests.
```
plan:
  stage: build
  script:
    - terraform plan -out=$PLAN
    - terraform show --json $PLAN | convert_report > $PLAN_JSON
  artifacts:
    reports:
      terraform: $PLAN_JSON
```
Running the pipeline displays the widget in the merge request, like this:
Selecting the View Full Log button in the widget takes you directly to the plan output present in the pipeline logs: