CLICommands

l4 diff

l4 diff shows the cost delta between your current Terraform state and a baseline. By default the baseline is the git merge-base (main or master); you can also point it at a saved snapshot file.

l4 diff main.tf
l4 diff ./infra/
l4 diff --base main ./infra/
l4 diff baseline.json ./infra/
The default baseline comes out of git history, and both GitHub Actions and GitLab CI check out a shallow clone, which leaves no merge-base to compare against. CI/CD integration sets the checkout depth each runner needs. Without history, diff against a saved baseline instead.

Flags

FlagDescription
--base <ref>Git ref to diff against (default: auto-detect main or master)
--region <r>AWS region for pricing (default us-east-1)
--gcp-region <r>GCP region (default: auto-detect or us-central1)
--azure-region <r>Azure region (default: auto-detect or eastus)
--var <key=value>Terraform variable (repeatable)
--var-file <path>Terraform variable file (repeatable)
--download-modulesDownload remote modules for accurate estimates (default true)
--fail-above <amount>Exit code 2 if monthly delta exceeds this threshold
--formattable, json, or github-comment (default table)

Global flags (--json, --jq, --template, --quiet, --token, --api) apply. See CLI overview.

CI gate

Fail the build when a pull request adds more than $100 a month:

l4 diff --fail-above 100 -q ./infra/

Over the threshold l4 diff exits 2 (ExitIssuesFound), which a job can tell apart from the 1 a generic failure returns. Exit codes has the full set.

Comparing against a saved baseline

Outside a git repository, or while you stage a multi-step deployment, diff against a snapshot that l4 estimate --out-file wrote earlier:

l4 estimate --out-file baseline.json ./infra/
# ... make changes ...
l4 diff baseline.json ./infra/

Posting to a pull request

--format github-comment emits Markdown you can pipe into a comment:

l4 diff --base main --format github-comment ./infra/ \
  | gh pr comment "$PR_NUMBER" --body-file -
  • l4 estimate: the absolute monthly cost, and the --out-file snapshot this command reads
  • CI/CD integration: the GitHub Actions and GitLab CI jobs that run l4 diff on a pull request
  • Output formats: --json, --jq, --template and --quiet

l4 estimate

Parse Terraform files locally and estimate monthly cloud costs before resources are created.

l4 export

Bulk-export costs and recommendations to CSV or JSON for spreadsheets, BI tools, or archival.

On this page

FlagsCI gateComparing against a saved baselinePosting to a pull requestRelated