Kubernetes 1.11: IPVS GA, CoreDNS GA & kubeadm Maturity

Introduction

On June 27 2018, Kubernetes 1.11 was officially released.
This release marks a continued evolution of scalability, flexibility and production‐readiness in Kubernetes, with major features graduating to GA, etcd receiving an upgrade, and cluster lifecycle tooling reaching new maturity.

Official Highlights

1. IPVS-Based In-Cluster Load Balancing (GA)

Kubernetes 1.11 graduates IPVS-based in-cluster load-balancing to General Availability, replacing the slower iptables mode and unlocking higher network throughput, lower latency and better scaling for Services.

2. CoreDNS as Default DNS Add-on Option (GA)

The CoreDNS plugin becomes a GA option for cluster DNS, offering a lighter, faster and more extensible DNS subsystem.

3. CRD Versioning & Subresources (Beta)

Custom Resource Definitions (CRDs) gain support for versioning and sub-resources, making it easier to evolve custom APIs and Operator frameworks.

4. Storage & Provider Integration Improvements

• Storage plugins (via Container Storage Interface/CSI) continue to mature, with out-of-tree drivers gaining richer sidecars and topology awareness.
• GCE PD regional EBS volumes arrive, Azure managed disks improve stability, and AWS ALB ingress controller integrations smooth out multi-zone clusters.

5. kubeadm Enhancements

• kubeadm configuration API hit beta, enabling declarative cluster configs stored in Git.
• CoreDNS became the default addon for kubeadm-created clusters, with built-in upgrades from kube-dns.
• HA cluster bootstrapping and phase workflows (kubeadm init phase) simplified control-plane expansion.

6. etcd 3.2 Upgrade & Control Plane Polish

• Default etcd version bumped to 3.2.18, improving snapshot compaction, gRPC proxy reliability, and disaster recovery tooling.
• Cloud Controller Manager (CCM) feature gates progressed, with external cloud providers (GCP, AWS, Azure) getting clearer separation from the core controller manager.

Field Notes & Best Practices

• IPVS adoption: ensure kube-proxy runs with --proxy-mode=ipvs and that kernel modules (ip_vs, ip_vs_rr, nf_conntrack_ipv4) are preloaded to avoid fallback to iptables.
• CoreDNS migration: validate custom stub domains rewrite properly in Corefile; leverage our CoreDNS 1.2 guide for plugin tuning.
• kubeadm configs: check rendered ClusterConfiguration via kubeadm config view after upgrades, and commit YAML to version control for audit trails.

Upgrade Watch-outs

• Back up etcd snapshots before upgrading—etcd 3.0 or 3.1 clusters require the one-time upgrade path documented by SIG-Cluster-Lifecycle.
• If you use admission controllers that depended on Initializers, replace them with mutating admission webhooks (alpha in 1.11).
• Verify custom cloud-controller integrations; some in-tree cloud provider code paths now require separate CCM deployments.

Milestones Timeline

Patch Releases for 1.11

Patch releases in the 1.11.x branch include bug fixes, security updates, compatibility patches and further stability refinements.

Legacy and Impact

Kubernetes 1.11 further solidified Kubernetes as a high‐throughput, enterprise‐grade platform, by delivering GA features in networking (IPVS), DNS (CoreDNS), extensibility (CRDs versioning), and storage integration.
These advancements enabled production clusters to scale more efficiently, integrate more providers and support richer custom APIs, while kubeadm and etcd upgrades made day-two operations more dependable.

Deprecations & Gotchas

• Dynamic Kubelet Config remained beta but now expects kubelet-config.v1beta1; convert older ConfigMaps before applying.
• The Aggregated API server now enforces stricter TLS requirements—ensure aggregated services present valid cert chains.
• kube-apiserver flag --insecure-port is on the deprecation path; migrate automation away from port 8080 access.

Summary

Next in the Series

Up next: Kubernetes 1.12 (September 2018) — we’ll explore TLS bootstrap for kubelets, Azure VMSS support and more infrastructure enhancements.