Kubernetes v1.27 Update Brings Chill Vibes
Kubernetes v1.27, the first K8s release of 2023, has been announced. The v1.27 release includes 60 enhancements, 18 of which are alpha, 29 are beta and 13 are stable at the time of writing. Due to a surprisingly easy release process, the maintainers have coined v1.27 the Chill Vibes release.
Many enhancements are simply graduations of preexisting features, but there are some new advancements that developers should pay attention to hidden in the release notes. I met with the lead maintainer for v1.27, Xander Grzywinski, senior product manager, Microsoft, to get the inside scoop.
Key Updates in Kubernetes v1.27
First, one update of note is that the newer image registry, registry.k8s.io, is replacing k8s.gcr.io. This change is something that’s been on the radar for a while, but registry.k8s.io is now the official default registry in v1.27.
The release notes also highlight that the SeccompDefault feature graduated to stable. This capability allows kubelet to run a stronger set of security defaults on a per-node basis. Another graduated feature is mutable scheduling directives for Jobs, which has reached GA. This enables more nuanced controls over parallel jobs.
The release announcement also cites some other other enhancements:
- DownwardAPIHugePages graduates to stable
- Pod Scheduling Readiness goes to beta
- Node log access via Kubernetes API
- ReadWriteOncePod PersistentVolume access mode goes to beta
- Respect PodTopologySpread after rolling upgrades
- Faster SELinux volume relabeling using mounts
- Robust VolumeManager reconstruction goes to beta
- Mutable Pod Scheduling Directives goes to beta
Diving Deeper Into Alpha Features
While the above topline themes may interest some users, Grzywinski notes that some other advancements may be more exciting for developers working with Kubernetes.
For example, he’s excited about in-place vertical pod autoscaling, which has reached an alpha state. This feature allows you to scale the request and limit numbers when you deploy a pod. “This can help scale the resource requests of a pod based on usage in place without having to redeploy a pod or scale horizontally,” explains Grzywinski. In-place vertical pod autoscaling could bring more intelligent capacity planning to developers packing their nodes and running larger clusters.
Although there is still some debate on the approach, Grzywinski highlights the growing interest in using sidecars. And Kubernetes v1.27 brings a way to define sidecars as a specific container type. “Having a mechanism by which kublet treats them differently to support that usage pattern will be helpful for a lot of people,” he says.
Lastly, Grzywinski mentions the new ReadWriteOnce storage access method, which restricts storage volumes to only be accessible by one pod at a time. Storage primitives and Persistent Volumes have come a long way, and these new features will further enable persistent storage on Kubernetes. “There’s been a lot of work done to get storage on Kubernetes to a point where it’s production safe,” says Grzywinski.
Boring Ain’t All That Bad
“It seems like this is one of the first big ‘boring’ releases. Big in that there’s a lot of content; boring in that there’s a lot of refinement,” he says.
At this point, Kubernetes’ core functionality is pretty fleshed out. And the latest work has been focused on refining things and making it function for as many users as possible, says Grzywinski.
Over the years, the Kubernetes maintainers have made many improvements to the feature tracking process, making v1.27 one of the most seamless releases to date. They encountered zero exception requests after the enhancement freeze, which is almost unheard of. “Hopefully, it makes things easier for engineers to get features in. The release process, to some degree, has put itself on autopilot.”
Looking ahead to the future roadmap, Grzywinski is excited about more KMS V2 improvements, led by the SIG Auth, which will help how Kubernetes users encrypt their etcd data using keys managed by cloud providers.
The full details of the v1.27 Kubernetes release can be found in the release notes. Grzywinski also recommends reading the deprecations and removal notes and especially keeping the new image registry change in mind.