Fairwinds Polaris vs KubeLinter

Fairwinds Polaris is an open source policy engine for validating and remediating Kubernetes resource configuration. It includes more than 30 built-in policies, and teams can add their own using JSON Schema. Checks cover security practices such as least privilege, privilege escalation, root execution, and host IPC or PID settings, along with resource requests and limits, readiness and liveness probes, and image tags. Polaris can run as a dashboard, an admission controller, or a command-line tool for checking local YAML files in CI/CD. Its validating webhook rejects workloads that trigger danger-level checks; warning-level findings pass and appear in the dashboard or webhook logs. A mutating webhook or command-line run can automatically remediate supported issues, including missing limits and probes and some unsafe security settings. The dashboard can audit local files or connect to a live cluster, and can be installed with kubectl or Helm. The validating webhook requires a valid TLS certificate. Polaris is free and runs on Linux, macOS, Windows, web, and self-hosted environments.

KubeLinter is a free, open-source static analyzer for Kubernetes YAML files, Helm charts, and Kustomize manifests. It checks production-readiness and security practices, including non-root containers, least privilege, and keeping sensitive information in secrets. Users can enable or disable checks and create custom checks for organizational policies. Failed checks produce remediation recommendations and a non-zero exit code. KubeLinter can generate several output formats in one run, including SARIF and JSON, and supports pull request scanning. Documented installation methods include Go, release binaries, Homebrew or LinuxBrew, nix-shell, and Docker. Container images are signed with cosign, with a public verification key supplied. The project uses the Apache License 2.0 and lists no paid tiers. Its README identifies StackRox as creator and Red Hat as current maintainer. The README also warns that commands, flags, and configuration formats may change. The latest listed release is v0.8.3.