Linode Kubernetes Engine v1.21.0

• Added support for Graceful Node Shutdown in v1.20 and v1.21 clusters. Existing clusters must recycle their nodes to finish the upgrade.
• Added support for optional eBPF data planes by having new LKE nodes mount the BPF filesystem on startup.

• Upgraded clusters using Kubernetes 1.20 to patch version 1.20.7.
• Upgraded clusters using Kubernetes 1.19 to patch version 1.19.11.
• Upgraded clusters using Kubernetes 1.18 to patch version 1.18.19.
• Upgraded coreDNS image from v1.8.0 to v1.8.4
• Upgraded Calico CNI from v3.10.4 to v3.19.0

• Disabled rpcbind by default on new LKE nodes, to avoid having unnecessary ports open.
• Fixed bug where kubelet and kubeadm configs in v1.21 clusters would still mention v1.20 text.