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typhoon/docs/topics/security.md

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Security

Typhoon aims to be minimal and secure. We're running it ourselves after all.

Overview

Kubernetes

  • etcd with peer-to-peer and client-auth TLS
  • Kubelets TLS bootstrap certificates (72 hours)
  • Generated TLS certificate (365 days) for admin kubeconfig
  • NodeRestriction is enabled to limit Kubelet authorization
  • Role-Based Access Control is enabled. Apps must define RBAC policies for API access
  • Workloads run on worker nodes only, unless they tolerate the master taint
  • Kubernetes Network Policy and Calico NetworkPolicy support 1

Hosts

  • Container Linux auto-updates are enabled
  • Hosts limit logins to SSH key-based auth (user "core")
  • SELinux enforcing mode 2

Platform

  • Cloud firewalls limit access to ssh, kube-apiserver, and ingress
  • No cluster credentials are stored in Matchbox (used for bare-metal)
  • No cluster credentials are stored in Digital Ocean metadata
  • Cluster credentials are stored in AWS metadata (for ASGs)
  • Cluster credentials are stored in Azure metadata (for scale sets)
  • Cluster credentials are stored in Google Cloud metadata (for managed instance groups)
  • No account credentials are available to Digital Ocean droplets
  • No account credentials are available to AWS EC2 instances (no IAM permissions)
  • No account credentials are available to Azure instances (no IAM permissions)
  • No account credentials are available to Google Cloud instances (no IAM permissions)

Precautions

Typhoon limits exposure to many security threats, but it is not a silver bullet. As usual,

  • Do not run untrusted images or accept manifests from strangers
  • Do not give untrusted users a shell behind your firewall
  • Define network policies for your namespaces

Container Images

Typhoon uses upstream container images (where possible) and upstream binaries.

!!! note Kubernetes releases kubelet as a binary for distros to package, either as a DEB/RPM on traditional distros or as a container image for container-optimized operating systems.

Typhoon packages the upstream Kubelet and its dependencies as a container image. Builds fetch the upstream Kubelet binary and verify its checksum.

The Kubelet image is published to Quay.io and Dockerhub.

Two tag styles indicate the build strategy used.

  • Typhoon internal infra publishes single and multi-arch images (e.g. v1.18.4, v1.18.4-amd64, v1.18.4-arm64, v1.18.4-2-g23228e6-amd64, v1.18.4-2-g23228e6-arm64)
  • Quay and Dockerhub automated builds publish verifiable images (e.g. build-SHA on Quay, build-TAG on Dockerhub)

The Typhoon-built Kubelet image is used as the official image. Automated builds provide an alternative image for those preferring to trust images built by Quay/Dockerhub (albeit lacking multi-arch). To use the fallback registry or an alternative tag, see customization.

flannel-cni

Typhoon packages the flannel-cni container image to provide security patches.

Disclosures

If you find security issues, please email security@psdn.io. If the issue lies in upstream Kubernetes, please inform upstream Kubernetes as well.

  1. Requires networking = "calico". Calico is the default on all platforms (AWS, Azure, bare-metal, DigitalOcean, and Google Cloud). ↩︎

  2. SELinux is enforcing on Fedora CoreOS, permissive on Flatcar Linux. ↩︎