c7n-left review
A focused Terraform policy checker for teams that want Cloud Custodian controls in pull requests.
Reviewed by iTechGuides Editors · Editorial team · Updated Oct 2026
c7n-left is an open-source command-line tool from Cloud Custodian for evaluating Cloud Custodian policies against infrastructure-as-code source assets. It is aimed at developers and platform or security teams that want to identify policy issues in Terraform before deployment. The tool runs on macOS and Linux, supports Docker distribution, and is intended for Windows use through Docker. Its focus is clear: Terraform analysis with policy-driven checks rather than broad coverage across many infrastructure-as-code frameworks.
For Terraform workflows, c7n-left provides several useful inspection controls. Teams can filter policies and resources by name, category, severity, type, and ID, then inspect relationships through resource-graph traversal. Support for Terraform data resources extends checks beyond standard managed resources. Policy testing with Terraform fixtures and assertions also gives maintainers a way to validate custom policies as they evolve. These capabilities suit teams that already work with Cloud Custodian and want checks to reflect their own infrastructure rules.
Workflow integration is centered on developer tooling. c7n-left offers JSON, CLI, and GitHub output formats, with GitHub output designed for pull-request annotations. GitHub Actions, Docker, and Terraform are listed integrations, while Docker image distribution provides an option for consistent execution in automation. The main trade-off is scope: its verified focus is Terraform and Cloud Custodian, so teams seeking a broader multi-framework IaC security platform should consider alternatives. Choose c7n-left for open-source Terraform policy enforcement and customizable checks; look elsewhere if wide framework coverage is the priority.
c7n-left pros and cons
- Where it wins
- Evaluates Cloud Custodian policies against Terraform source assets
- Traverses related resources and supports Terraform data resources
- Adds GitHub pull-request annotations with policy findings
- Where it doesn't
- Its verified scope is narrower than multi-framework alternatives
- Windows use is recommended through Docker
- Requires familiarity with Cloud Custodian policies and Terraform
c7n-left fact sheet, pricing and score →
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