The Kubernetes team has unloaded a new version – 1.11 – of the container orchestration platform.
Earlier this week, we spoke to Red Hat's Derek Carr on managing extensions for the latest release of K8s. Now, let's take a quick tour of this open-source project's new features.
CoreDNS and IPVS load balancing
CoreDNS, an authoritative DNS server written in Go, has gone to general availability. While KubeDNS remains available, the team warns that CoreDNS will be the default when using kubeadm.
More interestingly, IPVS-based in-cluster service load balancing has also gone live. Pointing to a glorious future where Kubernetes administrators do not need twist their brains around iptables to make things scalable, IPVS offers a simpler programming interface and better performance.
Where iptables provide a sequentially parsed table of routing rules for traffic, IPVS uses a kernel space hash table to speed things along. Unlike CoreDNS, IPVS is not yet the default, but the team reckons it is safe for production traffic if you're feeling saucy.
Need more storage? Don't fancy unmounting? No problem
Users willing to live at the bleeding edge will find alpha features geared around making storage flexible. Persistent volumes can be resized without the user having to unmount the volume first. The count of volumes that can be attached to a node can now be dynamic rather than hard coded or held in an environment variable.
Probably best not pointing those functions at production systems just yet, though. The team hopes they will be stable by release 1.12.
What is stable is the StorageObjectInUseProtection, which does exactly what the name implies. Previously known as "Persistent Volume Claim Protection", the function stops careless deletion of Storage Objects (or Persistent Volumes) that are actually being used.
CRD no longer crud
Custom Resource Definitions (CRD) provide a way to define extensions to the Kubernetes API. This is all well and good, but isn't so good at handling the situation where different versions of the resource exist.
With 1.11, multiple versions can now be defined, allowing resource authors to offer a migration path for their wares. The Kubernetes team plans to further extend this functionality to offer automatic conversions.
Come on in, dear boy, have a SIG
The release also contains the usual swathe of features from Kubernetes' community of Special Interest Groups (SIG). The Azure SIG, for example, allows Azure disks to support external resource groups and VM names to include the underscore character.
Version 1.11, the second release of 2018, is available now. ®