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Hack The Garden 09/2022 Wrap Up

IPv6

  • There is an open PR which adapts some assumptions about the IPv4 CIDRs in gardener/gardener (changes are rather minimal).
  • Shoot creation currently stops at 83%.
  • DNSRecord extension needs to be adapted to support AAAA records.
  • Focus was on the local setup only for now (which comes with its own issues). As a follow-up, we want to try the same with real infrastructures.
  • Everybody is invited to try the IPv6 setup at home (where you have IPv6 internet access) and provide feedback in the open PR.
  • With IPv6, the network CIDRs cannot be defined before shoot cretion (which is different compared to how it works with IPv4 today). We need to discuss the target picture.

Canary Rollout

  • There is a PoC which marks Seeds as canaries and works with both extensions and new gardenlet versions.
  • A new freeze controller would stop gardenlets from continuing reconciling Shoots in case too many clusters became unhealthy after the update.
  • The ManagedSeed controller now also uses ControllerDeployments for rolling out gardenlets.
  • There are still some open questions, e.g. "how to validate provider extensions" (given that a seed cluster is typically only responsible for one provider) and "how to determine the canary seeds".
  • We have to discuss the approach and solve the open questions before writing up a GEP.

Registry Cache Extension

  • There is a new controller (gardener/gardener-extension-registry-cache) for Extension resources which deploys the Docker registries (one per upstream repository) into the shoot cluster.
  • The containerd configuration for the mirrors is stored in a ConfigMap and picked up by a DaemonSet from there which applies it and restarts the containerd.
  • The DaemonSet pods are quite privileged and we need to discuss how to improve security concerns here (don't use it in production for now).
  • Some unit and integration tests (and docs) are missing and have to be added, however Prow is already connected to it.
  • There is an issue with containerd which only allows mirrors to be configured from one file.
  • There was also a bug in gardener/gardener which prevented additional containerd imports from working properly.
  • Another issue in gardener/gardener was found regarding removing the extension from shoot clusters (still needs to be investigated).
  • Potentially, we should refactor the current implementation to rely on OperatingSystemConfig webhooks.

Access Control For Shoot Clusters

  • The open PR from Gerrit in gardener/gardener was closed in favor of an extension developed by StackIT.
  • It needs to be adapted to a new approach using EnvoyFilters instead of AuthorizationPolicys (otherwise, we would risk kube-apiserver outages).
  • End-users should not be bothered with specifying the "right" IPs (source IPs vs. proxy protocol). For this, the provider extension need to be adapted to make this convenient for the users. (This is only for convenience - the extension can operate on its own).
  • The 23T colleagues created a new GitHub organization called gardener-community which might be a good place to host this new extension.

Cilium Support For Metal Stack

  • The Cilium extension was enhanced to support some more configuration options which make Cilium now possible on Metal Stack.
  • In addition, Cilium was tested successfully with provider-local (works out of the box).

Kubelet Server Certificate

  • The kubelet was still using a self-signed server certificate (valid for 1y) and was now adapted to create CertificateSigningRequest resources (same process compared to what it does to retrieve its client certificate).
  • There is a new controller in gardener-resource-manager which approves such CSRs so that kube-controller-manager can issue the certificate.
  • With this, the server certificate is only valid for 30d and rotated regularly.
  • Documentation and tests are still missing and need to be adapted.
  • OpenShift follows a similar approach (they have their own CSR approver controller).

Replacement Of The Last Remaining Shell Script In Metal Stack

  • Awesome

Resource Manager Health Check Watches

  • Previously, the health controller was polling periodically which caused quite some delays in reporting the actual status of the world.
  • This prolonged various operations unnecessarily.
  • Now, it watches all resources it detects in the status of the ManagedResource which makes it reacting MUCH faster. 🎉
  • This only works for the ManagedResources in the seed since we currently disable the cache for shoot clusters (however, enabling it comes with quite more memory usage, so we have to check).