Install c7n with Homebrew, apt

Project links

• Homepage
• Repository
• Upstream docs
• Package manager page

Commands and aliases

• custodian

Project history

Cloud Custodian began at Capital One as a way to replace many ad hoc cloud-management scripts with a shared policy engine. Its README describes the project as a rules engine for managing public cloud accounts and resources, using simple YAML policies composed from resource types, filters, actions, and execution modes.

The project expanded from an AWS-oriented governance tool into a multi-cloud framework supporting AWS, Azure, GCP, OCI, Tencent Cloud, Kubernetes, and related tools. Its documentation presents compliance-as-code as a central model: users validate, dry-run, and review policies before applying them to cloud resources.

The CNCF project page records Cloud Custodian's acceptance into CNCF on June 25, 2020 and its move to incubating maturity on September 14, 2022.

Adoption history

Cloud Custodian's adoption story is unusually strong for a CLI governance tool because it grew out of large-scale production cloud use and then moved into CNCF stewardship. The README describes it as led by a community of hundreds of contributors and battle-tested in very large cloud environments.

The project is distributed as the c7n Python package family, a Docker image, and OS-package-manager formulas such as Homebrew. Its docs also cover companion tools such as c7n-org, c7n-mailer, c7n-left, c7n-kube, and c7n-logexporter, reflecting an ecosystem around core policy evaluation.

How it is used

Users write YAML policies, validate them, dry-run them, and run them with the custodian CLI. Policies can check resources for tag compliance, encryption, public exposure, age, cost waste, and other conditions, then take actions such as tagging, stopping, deleting, notifying, or invoking provider-native eventing.

Cloud Custodian can run as a local or CI job against existing fleets, or it can provision serverless/event-driven execution through cloud provider facilities such as AWS CloudWatch Events, AWS Config rules, Azure Event Grid, GCP Audit Log and Pub/Sub, and similar mechanisms.

Why package nerds care

For package nerds, c7n is significant because the tiny package name hides a broad cloud-governance platform. Installing a single CLI brings in a policy language, schema tooling, multi-cloud resource providers, serverless deployment paths, reporting, and a family of c7n-* companion packages.

It is also a canonical example of Python CLI tooling becoming infrastructure governance plumbing: a package-manager install turns YAML files into enforceable cloud controls.

Timeline

• 2015-12-21: The Sphinx documentation scaffold date appears in the docs source.
• 2020-06-25: Cloud Custodian was accepted into CNCF.
• 2022-09-14: Cloud Custodian moved to CNCF incubating maturity.
• 2026: The project remains documented by CNCF as an incubating project.

Related projects

• c7n-org helps run policies across many accounts or subscriptions.
• c7n-mailer handles notifications for policy matches.
• c7n-left applies Custodian-style checks to infrastructure-as-code assets.
• c7n-kube extends the policy model into Kubernetes.

Sources

• https://cloudcustodian.io/docs/
• https://cloudcustodian.io/docs/quickstart/index.html
• https://github.com/cloud-custodian/cloud-custodian
• https://www.cncf.io/projects/cloud-custodian/