hooks-infracost

Demonstrates the infracost hook kind: an after.terraform.plan hook that runs an Infracost-compatible command against the component and renders a cost summary in the terminal.

What this shows

• kind: infracost using the same hook args, output file, failure mode, and result handler as real Infracost.
• A local bin/infracost-emulator command keeps the example deterministic for docs and tests while still exercising the hook execution path.
• Single markdown rendering used everywhere: when Atmos Pro is connected the same body is uploaded; in the terminal it renders via ui.Markdown().

Requirements

• Terraform on PATH.
• No AWS credentials needed — the component uses dummy AWS provider config so terraform plan succeeds offline.

For real Infracost usage, remove the command: ./bin/infracost-emulator override, add dependencies.tools.infracost, and set INFRACOST_API_KEY (free at https://www.infracost.io/). Infracost needs that key to access its cloud-hosted pricing database.

Run

atmos terraform plan nat-gateway -s test

Expected: terraform plan succeeds; the after.terraform.plan hook fires; the Infracost-compatible emulator writes the same JSON shape as infracost breakdown --format json, and Atmos prints a markdown cost summary showing the NAT gateway and EIP monthly costs.

Files

• atmos.yaml — Atmos config.
• stacks/deploy/test.yaml — stack with a single component and one hook.
• components/terraform/nat-gateway/ — minimal NAT gateway + EIP module.
• bin/infracost-emulator — deterministic executable that implements the output-file contract used by the Infracost hook.

Notes

subnet_id is a placeholder ID. We don't need a real subnet because we never apply — infracost prices resources from HCL/plan, not from live state.