AWS Control Tower vs Cloud Custodian

AWS Control Tower sets up and governs multi-account AWS environments, bringing account structure, identity and policy enforcement under centralized management. It automates landing zone setup for new or existing AWS Organizations, including federated access and central backup integrations. Account Factory provisions accounts from configurable templates, with support for custom resources and requirements. Organizations can also use the Control Catalog on its own: it contains 750+ managed controls for security, cost, durability and operations. Controls can be detective, preventive or proactive; proactive controls use AWS CloudFormation Hooks to identify and block noncompliant deployments. Predefined integrations include AWS Organizations, IAM Identity Center, AWS Config, AWS Backup and AWS CloudTrail. AWS Marketplace also offers integrated third-party solutions. Control Tower has an API. The service has a free plan and no additional charge for Control Tower itself; underlying AWS services are billed based on usage, and optional controls or configured resources may add costs. The landing zone’s home Region cannot be changed after creation, and some detective and proactive controls do not work in every supported Region.

Cloud Custodian manages cloud resources through policies written in YAML. Each policy names a resource type, filters for selecting resources, and actions to apply to matches. It supports security policy enforcement, compliance, tag policies, cleanup of unused resources, and cost management for AWS, Azure, and Google Cloud Platform resources. Policies can respond to provider events through serverless features or run on a cron schedule. Users can validate policies and preview matching resources in dry-run mode before actions execute. Runs can produce policy metrics, structured resource records, and logs for cloud metrics, storage, and logging services. Documented event connections include AWS CloudWatch Events and Config Rules, Azure EventGrid, and GCP AuditLog and Pub/Sub. Installation is documented for Linux, macOS, and Windows, with Docker and Kubernetes operation also described. Kubernetes, Tencent Cloud, and OpenStack support are in beta; Terraform integration is in alpha. Cloud Custodian is free at free and open source under Apache 2.0. An AWS constraint is that event-triggered policies run only in the same region and account, while periodic policies may run elsewhere.