- Base-images: Update to debian-iptables:buster-v1.4.0
  - Uses iptables 1.8.5
  - base-images: Update to debian-base:buster-v1.3.0
  - cluster/images/etcd: Build etcd:3.4.13-2 image
    - Uses debian-base:buster-v1.3.0 ([#98401](https://github.com/kubernetes/kubernetes/pull/98401), [@pacoxu](https://github.com/pacoxu)) [SIG Testing]

### Cluster Lifecycle

#### kubeadm

* [beta] A new `upgrade` subcommand allows you to automatically upgrade a self-hosted cluster created with kubeadm. ([#296](https://github.com/kubernetes/enhancements/issues/296), [@luxas](https://github.com/luxas))

- Deprecated `genericclioptions.IOStreams` and used `genericiooptions.IOStreams`. ([#117102](https://github.com/kubernetes/kubernetes/pull/117102), [@ardaguclu](https://github.com/ardaguclu))

- Base images: Updated to
  - debian-base:buster-v1.6.0
  - debian-iptables:buster-v1.6.0 ([#100976](https://github.com/kubernetes/kubernetes/pull/100976), [@jindijamie](https://github.com/jindijamie))
- Base-images: Update to `debian-base:buster-v1.7.1` ([#102594](https://github.com/kubernetes/kubernetes/pull/102594), [@mengjiao-liu](https://github.com/mengjiao-liu))

      endpoints, rather than waiting until all of the terminating
      endpoints have terminated even when those terminating endpoints
      were not being used.
  
    - Chains for endpoints that won't be used are no longer output to
      iptables, saving a bit of memory/time/cpu. ([#106030](https://github.com/kubernetes/kubernetes/pull/106030), [@danwinship](https://github.com/danwinship)) [SIG Network]

- Some interfaces' signatures in the scheduler were updated: - PluginsRunner: used NodeInfo in `RunPreScorePlugins` and `RunScorePlugins`. - PreScorePlugin: used NodeInfo in `PreScore`. - Extender: used NodeInfo in `Filter` and `Prioritize`.
   ([#121954](https://github.com/kubernetes/kubernetes/pull/121954), [@AxeZhan](https://github.com/AxeZhan))

- Listed the pods using `<PVC>` as an ephemeral storage volume in "Used by:" part of the output of `kubectl describe pvc <PVC>` command. ([#120427](https://github.com/kubernetes/kubernetes/pull/120427), [@MaGaroo](https://github.com/MaGaroo))

plugin and the `kubernetes.io/enforce-mountable-secrets` annotation are used together with ephemeral containers.

**Note**: This only impacts the cluster if the ServiceAccount admission plugin is used (most cluster should have this on by default as recommended in https://kubernetes.io/docs/reference/access-authn-authz/admission-controllers/#serviceaccount), the `kubernetes.io/enforce-mountable-secrets` annotation is used by a service account (this annotation is not added by default), and...