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Infracost Atlantis Integration

Try the GitHub or GitLab App

👉👉 If you use Atlantis with GitHub/GitLab, we recommend using the free Infracost GitHub App or GitLab App as they're much simpler to setup and faster to run

This repo shows how Infracost can be used with Atlantis, so you can see cloud cost estimates and FinOps best practices for Terraform in pull requests 💰

Example screenshot

Usage

1. Decide deployment option

Since Atlantis does not have a plugins concept, you need to decide which deployment option to use:

a. Use our Docker images (recommended)

Use our infracost-atlantis Docker images that extend the Atlantis image to add Infracost. We maintain tags for the latest two 0.x versions of Atlantis:

  • infracost/infracost-atlantis:atlantis0.31-infracost0.10 latest patch version of Atlantis v0.31 and Infracost v0.10
  • infracost/infracost-atlantis:atlantis0.30-infracost0.10 latest patch version of Atlantis v0.30 and Infracost v0.10
  • infracost/infracost-atlantis:latest latest versions of Atlantis and Infracost

b. Build your own Docker image

If you already use a custom Docker image for Atlantis, copy the top RUN command from this Dockerfile into your Dockerfile.

c. Install in pre-workflow (good for testing)

Use Atlantis pre_workflow_hooks to dynamically install the Infracost CLI on a running Atlantis server (shown in the following repos.yml example). This enables you to test Infracost without changing your Docker image by installing it on each workflow run. Once you're happy with the results, you can use one of the above methods.

To use this method, add the following pre_workflow_hook to your chosen option in the next step. Also change references to the Infracost CLI invocation to /tmp/infracost in the the next step. Environment variables such as INFRACOST_API_KEY also need to be passed into the Atlantis container.

repos:
  - id: /.*/
    workflow: terraform-infracost
    pre_workflow_hooks:
      # Install Infracost, use `/tmp/infracost` to run the CLI in step 2
      - run: |
          /tmp/infracost --version && [ $(/tmp/infracost --version 2>&1 | grep -c "A new version of Infracost is available") = 0 ] || \
            curl -L https://infracost.io/downloads/v0.10/infracost-linux-amd64.tar.gz --output infracost.tar.gz && \
            tar -xvf infracost.tar.gz && \
            mv infracost-linux-amd64 /tmp/infracost

2. Setup Infracost

Once you've decided, follow this guide to setup Infracost with Atlantis.

3. Test the integration

Follow these simple steps to test the integration. This is important as it ensures the CLI commands are running correctly in your workflow 👌

  • Infracost Cloud is our SaaS product that builds on top of Infracost open source. It enables team leads, managers and FinOps practitioners to setup tagging policies, guardrails and best practices to help guide the team. For example, you can check for required tag keys/values, or suggest switching AWS gp2 volumes to gp3 as they are more performant and cheaper.

    If you do not want to use Infracost Cloud, go to Org Settings and disable the dashboard. This causes the CLI not to send its JSON output to your dashboard; the JSON does not contain any cloud credentials or secrets, see the FAQ for more information.

    Infracost Cloud enables you to check for best practices such as using latest generation instance types or block storage, as well as setup tagging policies and guardrails to help guide the team.

Atlantis usage notes

Private Terraform modules

To use with Terraform modules that are hosted in a private git repository you can add the --write-git-creds flag to your atlantis server command.

Project names

Project names default to the relative path of the project using the Atlantis $REPO_REL_DIR environment variable. See our docs to customize this.

Terragrunt

If you use Atlantis with Terragrunt, you should:

  1. Update your Docker image to include terragrunt, for example:

    FROM infracost/infracost-atlantis:latest

RUN curl -L https://github.com/gruntwork-io/terragrunt/releases/download/v0.36.0/terragrunt_linux_amd64 --output terragrunt && \
    chmod +x terragrunt && \
    mv terragrunt /usr/local/bin

  2. Add the following YAML spec to repos.yaml or atlantis.yaml config files, altering it to fit your terragrunt project:

    repos:
  - id: /.*/
    workflow: terragrunt-infracost
workflows:
  terragrunt-infracost:
    plan:
      steps:
        - env:
            name: INFRACOST_OUTPUT
            command: 'echo "/tmp/$BASE_REPO_OWNER-$BASE_REPO_NAME-$PULL_NUM/$WORKSPACE-${REPO_REL_DIR//\//-}-infracost.json"'
        - env:
            name: TERRAGRUNT_TFPATH
            command: 'echo "terraform${ATLANTIS_TERRAFORM_VERSION}"'
        - run: terragrunt plan -out=$PLANFILE
        - run: terragrunt show -json $PLANFILE > $SHOWFILE
        # Add custom steps here from the examples mentioned elsewhere in this readme

Overriding metadata

If you use Infracost Cloud, you might need to override metadata such as the pull request author or title that is shown on the Infracost Cloud dashboard.

INFRACOST_VCS_PROVIDER="github" # For GitHub Enterprise, also use "github"
INFRACOST_VCS_REPOSITORY_URL="https://github.com/$BASE_REPO_OWNER/$BASE_REPO_NAME"
INFRACOST_VCS_PULL_REQUEST_URL="$INFRACOST_VCS_REPOSITORY_URL/pulls/$PULL_NUM"
INFRACOST_VCS_PULL_REQUEST_AUTHOR="$PULL_AUTHOR"
INFRACOST_VCS_BASE_BRANCH="$BASE_BRANCH_NAME"

INFRACOST_VCS_PULL_REQUEST_TITLE=\"$(curl -s \
    -H "Accept: application/vnd.github+json" \
    -H "Authorization: $GITHUB_TOKEN" \
    "https://api.github.com/repos/$BASE_REPO_OWNER/$BASE_REPO_NAME/pulls/$PULL_NUM" | jq -r '.title')\"

Contributing

Issues and pull requests are welcome! For development details, see the contributing guide. For major changes, including interface changes, please open an issue first to discuss what you would like to change. Join our community Slack channel, we are a friendly bunch and happy to help you get started :)

License

Apache License 2.0