Falco vs Open Policy Agent Gatekeeper

Falco is a free, open source runtime security project for Linux and self-hosted environments. It monitors hosts, containers, Kubernetes, and cloud environments for abnormal behavior, potential threats, and compliance violations in real time. Events are compared with built-in detection rules, and users can create rules for their own environments. Sources include Linux kernel system calls, Kubernetes audit logs, cloud events such as AWS CloudTrail, and events from GitHub and Okta. For kernel event monitoring, Falco uses an eBPF driver by default and offers a kernel module for wider compatibility. Installation options cover Linux hosts, Docker containers, and Kubernetes, including official Helm charts; supported architectures include x86_64 and ARM64. Falcosidekick can forward events to more than 50 systems, including email, chat, message queues, serverless functions, and databases. Falco is hosted by the CNCF as a graduated project. Detection depends on having appropriate rules in place, while resource use varies with server load and workload. The project recommends testing performance in the target environment.

Open Policy Agent Gatekeeper is a free, open-source Kubernetes policy controller for Linux and self-hosted deployments. It runs as a validating and mutating webhook, enforcing CRD-based policies evaluated by Open Policy Agent. Validation constraints can deny requests, warn, run in dry-run mode or report violations without changing resources. Mutation policies can alter matching resources during admission before validation checks the final object. An audit function periodically evaluates existing cluster resources against constraints to identify pre-existing misconfigurations. The project includes an extensible policy library with parameterized examples, and provider connections to external data such as image registries and directory services. Named integrations or backed services include Azure Policy for Kubernetes, Google Kubernetes Engine Policy Controller, Rancher, AWS EKS Blueprints and Alibaba Cloud. Installation options include prebuilt, development or locally built images and Helm. Gatekeeper requires Kubernetes resources introduced in version 1.16 and cluster-admin permissions for installation. The gator CLI is documented as beta from version 3.11.