New in Kubernetes 1.7: More extensibility with Custom Resource Definitions and API Aggregation

By Luis Pabón, June 29, 2017

Originally published on the CoreOS blog (archived copy) . Re-published with the authors' permission.

Kubernetes, the open source platform for managing containers at scale, is releasing version 1.7 this week. Over 375 different individuals had a hand stabilizing and adding new features to this version, and we would like to thank all of them for their effort, and celebrate our team members that also contributed to this release. Version 1.7 brings in a new set of features, plus it continues the construction of new interfaces to make Kubernetes more extensible with a more reliable core. This release showcases the new technologies which allow the creation of customized services extending the core of Kubernetes.

New Kubernetes feature updates at a glance

On every release, a number of new projects are introduced as alpha features. These new features give users a glimpse of what is to come, but at a risk to the stability of the feature due to its state. Some of these features are consumed by users quite heavily which helps developers mature the project and release it in future releases as a beta feature. At this stage, developers continue to harden and stabilize the feature including input from users and the community until the project moves into a stable state.

The table below shows how Kubernetes 1.7 continues advancement in innovation by introducing 19 new alpha features. This release also celebrates the maturing of previous features which can be now released as beta or stable.

Number of Features	Status
4	Stable
7	Beta
19	Alpha

New Kubernetes features: highlights for enterprises

Kubernetes brings in a new set of features to make it more extensible. Ultimately, its goal is to make it so that developers can deploy new features based on a stable, featureful, core Kubernetes system, enabling new features to be added on demand.

Here are some of the features available in version 1.7:

Custom Resource Definitions: CRDs are now beta and replace the previous alpha based Third Party Resources feature. CRD is an extremely important feature allowing the creation of custom objects used by applications managing resources on Kubernetes. For example, Operators will continue to benefit from this feature to provide users with self managed resources. Check out our post on CRDs for more details.
API Aggregation: Along with CRDs to continue the extensibility of Kubernetes, API Aggregation is moving to beta status and it enables Kubernetes to completely defer the request and response to another server. Whereas CRDs are a lightweight way of having the Kubernetes allocate scratch space for custom resources, aggregation is a completely pluggable way to customize Kubernetes’ API handling including specialized resource validation, or ACL filtering not available for normal resources.
Local persistent storage: Local persistent storage is now an alpha feature which allows users to request from a StorageClass that their Pods be executed on nodes with locally attached storage. This method will be a more reliable model of storing local persistent data as compared to hostPath. Check the storage volumes docs for more details.
Limit node access to API server: The API server can now prevent a node from reading resources, such a secrets, that are not needed by pods scheduled to it. This pairs with ongoing kubelet TLS bootstrapping work, a mechanism for delivering unique credentials for each node, a requirement for node restriction.
Encryption of secrets at rest: Alpha support for encrypting API resources, including secrets, at rest has been added. This allows the API server to symmetrically encrypt data before passing it to etcd.

What does that mean for Tectonic?

Our work in upstream Kubernetes helps CoreOS release the latest version of Kubernetes in CoreOS Tectonic quickly while at the same time allowing others to build off of our open source contributions. Tectonic uses pure, upstream Kubernetes, and this release will be available to Tectonic soon.

Join the Kubernetes community

CoreOS will lead a webinar on July 18 at 10 AM PT to dive into the new features of Kubernetes 1.7. Register here and join us to get your questions answered live.

Join the CoreOS team and get involved in the Kubernetes community!

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