Learn CLOUD-CUSTODIAN with Real Code Examples

Cloud Custodian allows defining policies as YAML files specifying filters and actions on cloud resources.

Supports enforcing security, cost optimization, compliance, and operational policies automatically.

Integrates with cloud provider APIs to query, tag, and manage resources in real time.

Can generate reports, remediate policy violations, and trigger notifications.

Widely used in cloud-native enterprises for governance, auditing, and cost control.

Resource discovery and inventory across clouds

Policy filtering by tags, types, age, and metrics

Action execution to remediate or notify

Support for cron, CloudWatch, and event-driven triggers

Extensible with custom filters and actions

Policy - YAML definition of filters and actions

Filter - criteria to select resources

Action - operation to execute on filtered resources

Mode - event-driven or scheduled policy execution

Resource - cloud entity targeted by policies (EC2, S3, IAM, etc.)

policies/ - YAML policy files

scripts/ - optional Python scripts for custom actions

reports/ - output reports from policy runs

logs/ - execution logs

README.md - documentation of policy purpose

Write a policy YAML defining resource, filters, and actions

Run `custodian run policy.yml` to test

Schedule policies using cron or event triggers

Integrate notifications or reporting actions

Iterate and refine policy definitions

Beginner: single resource type, basic filter/action

Intermediate: multiple resource filters with notifications

Advanced: multi-cloud policies with automated remediation

Expert: complex policies with custom filters/actions

Enterprise: governance automation at large scale

Cloud Custodian vs Terraform: policy enforcement vs infrastructure provisioning

Cloud Custodian vs AWS Config: richer multi-cloud policy definitions

Cloud Custodian vs Open Policy Agent: specialized vs generic policy engine

Cloud Custodian vs Chef Inspec: cloud governance vs compliance testing

Cloud Custodian vs native cloud console scripts: automated and scalable

2016 - Initial release by Capital One

2017 - Open-sourced under Apache 2.0 license

2018 - Added Azure and GCP support

2019 - Event-driven execution and notifications introduced

2025 - Mature multi-cloud policy engine with large community adoption

Policy - YAML definition of cloud governance rules

Filter - criteria to select resources

Action - operation to perform on resources

Mode - execution method (event or schedule)

Resource - cloud entity targeted by policies