Kubernetes: KubeInvaders, CSI Ephemeral Inline Volumes and Reviewing 2019 in Docs
-
KubeInvaders - Gamified Chaos Engineering Tool for Kubernetes
Some months ago, I released my latest project called KubeInvaders. The first time I shared it with the community was during an Openshift Commons Briefing session. Kubenvaders is a Gamified Chaos Engineering tool for Kubernetes and Openshift and helps test how resilient your Kubernetes cluster is, in a fun way.
-
CSI Ephemeral Inline Volumes
Typically, volumes provided by an external storage driver in Kubernetes are persistent, with a lifecycle that is completely independent of pods or (as a special case) loosely coupled to the first pod which uses a volume (late binding mode). The mechanism for requesting and defining such volumes in Kubernetes are Persistent Volume Claim (PVC) and Persistent Volume (PV) objects. Originally, volumes that are backed by a Container Storage Interface (CSI) driver could only be used via this PVC/PV mechanism.
But there are also use cases for data volumes whose content and lifecycle is tied to a pod. For example, a driver might populate a volume with dynamically created secrets that are specific to the application running in the pod. Such volumes need to be created together with a pod and can be deleted as part of pod termination (ephemeral). They get defined as part of the pod spec (inline).
Since Kubernetes 1.15, CSI drivers can also be used for such ephemeral inline volumes. The CSIInlineVolume feature gate had to be set to enable it in 1.15 because support was still in alpha state. In 1.16, the feature reached beta state, which typically means that it is enabled in clusters by default.
CSI drivers have to be adapted to support this because although two existing CSI gRPC calls are used (NodePublishVolume and NodeUnpublishVolume), the way how they are used is different and not covered by the CSI spec: for ephemeral volumes, only NodePublishVolume is invoked by kubelet when asking the CSI driver for a volume. All other calls (like CreateVolume, NodeStageVolume, etc.) are skipped. The volume parameters are provided in the pod spec and from there copied into the NodePublishVolumeRequest.volume_context field. There are currently no standardized parameters; even common ones like size must be provided in a format that is defined by the CSI driver. Likewise, only NodeUnpublishVolume gets called after the pod has terminated and the volume needs to be removed.
-
Reviewing 2019 in Docs
Hi, folks! I’m one of the co-chairs for the Kubernetes documentation special interest group (SIG Docs). This blog post is a review of SIG Docs in 2019. Our contributors did amazing work last year, and I want to highlight their successes.
Although I review 2019 in this post, my goal is to point forward to 2020. I observe some trends in SIG Docs–some good, others troubling. I want to raise visibility before those challenges increase in severity.
- Login or register to post comments
- Printer-friendly version
- 2469 reads
- PDF version
More in Tux Machines
- Highlights
- Front Page
- Latest Headlines
- Archive
- Recent comments
- All-Time Popular Stories
- Hot Topics
- New Members
digiKam 7.7.0 is releasedAfter three months of active maintenance and another bug triage, the digiKam team is proud to present version 7.7.0 of its open source digital photo manager. See below the list of most important features coming with this release. |
Dilution and Misuse of the "Linux" Brand
|
Samsung, Red Hat to Work on Linux Drivers for Future TechThe metaverse is expected to uproot system design as we know it, and Samsung is one of many hardware vendors re-imagining data center infrastructure in preparation for a parallel 3D world. Samsung is working on new memory technologies that provide faster bandwidth inside hardware for data to travel between CPUs, storage and other computing resources. The company also announced it was partnering with Red Hat to ensure these technologies have Linux compatibility. |
today's howtos
|
Recent comments
1 year 11 weeks ago
1 year 11 weeks ago
1 year 11 weeks ago
1 year 11 weeks ago
1 year 11 weeks ago
1 year 11 weeks ago
1 year 11 weeks ago
1 year 11 weeks ago
1 year 11 weeks ago
1 year 11 weeks ago