Dockle vs Kyverno

Dockle is a free, self-hosted container image linter focused on security and Docker best practices. It scans images for vulnerabilities and checks settings against CIS Docker Image Benchmarks, along with Docker- and Linux-specific issues such as empty passwords and duplicate user or group IDs. Results can be displayed or saved in JSON and SARIF formats. Users can set an exit level and ignore selected checkpoints through command options, environment variables, or a .dockleignore file. The project documents continuous-integration use and provides a GitHub Action, with examples for Travis CI, CircleCI, and GitLab CI. Dockle can access private images in Docker Hub, Amazon ECR, Google Container Registry, and self-hosted registries. It can also scan an image archive created with docker save by using the --input option. Installation routes include Homebrew, Linux distribution packages, Windows binaries, version managers, source builds, and Docker. Dockle runs on Linux, macOS, and Windows and is listed under the Apache-2.0 license.

Kyverno is a free, open-source policy engine for defining and enforcing policy as code in Kubernetes. Its stable policy types can validate, mutate, generate or delete resources, and verify container image signatures and attestations. The Kyverno CLI can test policies against Kubernetes resource manifests in CI before they are applied to a live cluster. Documentation describes use with Helm, YAML manifests, GitHub Actions and GitOps tools such as ArgoCD. Kyverno is installed in a Kubernetes cluster; Helm is recommended for production, and YAML manifests are also available. A standard installation requires an admission controller, while background, reports and cleanup controllers are optional. Production installations should use high availability mode. The project supports CEL-based policy types and describes applying Kubernetes-style policies outside Kubernetes as part of its mission. Its webhooks default to fail-closed, so matching requests can fail if the API server cannot reach Kyverno. The project documents Cosign signatures for images and manifests, and lists CLI binaries for Linux, macOS and Windows.