Kubernetes - What Are the Most Important Design Patterns and Principles?

What are the most important Kubernetes design patterns and principles?

kubernetes #externalsecretsoperator #security

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Secrets in Kubernetes - How to Transfer Secrets from One Cluster to Another?

How to transfer secrets from one Kubernetes cluster to another?

kubernetes #externalsecretsoperator #security

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Ep04 - Ask Me Anything About DevOps, Cloud, Kubernetes, Platform Engineering,... w/Scott Rosenberg

There are no restrictions in this AMA session. You can ask anything about DevOps, Cloud, Kubernetes, Platform Engineering, containers, or anything else. We'll have a special guest Scott Rosenberg to help us out.

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Mastering Kubernetes: Volumes (Persistent Volumes and Claims, ConfigMaps, Secrets, etc)

Dive into Kubernetes Volumes in this comprehensive tutorial! We'll cover local volumes like emptyDir, CSI Drivers, Storage Classes, Persistent Volumes, Persistent Volume Claims, ConfigMaps, and Secrets. Learn how to use these essential components in Kubernetes for efficient storage management. Understanding volumes is crucial whether you're developing locally or deploying in production. Follow along with practical examples and commands to master Kubernetes volumes. Perfect for beginners and experts alike.

Kubernetes #Volumes #PersistentStorage #KubernetesTutorial

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▬▬▬▬▬▬ 🔗 Additional Info 🔗 ▬▬▬▬▬▬ ➡ Transcript and commands: https://devopstoolkit.live/kubernetes/mastering-kubernetes-volumes-emptydir,-csi-drivers,-storage-classes,-persistent-volumes-and-persistent-volume-claims,-configmaps,-and-secrets 🔗 Kubernetes: https://kubernetes.io 🎬 Mastering Kubernetes: Workloads APIs (Deployment, StatefulSet, ReplicaSet, Pod, etc.): https://youtu.be/U6weXlzQxoY

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Control Plane - What Are The Main Benefits of Implementing It?

What are the main benefits of developing and implementing Control Planes?

controlplane #kubernetes

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Canary Deployments - What Are Examples Where It Can Be Used Other Than for Cloud Resources?

What are examples where Crossplane can (and should) be used other than for Cloud resources?

crossplane #kubernetes

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Canary Deployments - Is It a Good Practice to Combine Argo Rollouts with Ingress and Istio?

Canary Deployments - Is It a Good Practice to Combine Argo Rollouts with Ingress and Istio?

progressivedelivery #canarydeployments #kubernetes

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Week Ending December 15, 2024

https://lwkd.info/2024/20241216

Developer News

This will be the last LWKD issue of the year. Publication will resume in 2025 with the January 5th edition.

Submissions for the maintainer summit at Kubecon London are due January 12th. The CfP for the main tracks in Kubecon China, Kubecon India, and Kubecon Japan are now open.

Release Schedule

Next Deadline: 1.33 Cycle Begins, January ??

The 1.33 development cycle will begin in early January, but a specific schedule has not been set.

Featured PRs

128718 FG:InPlacePodVerticalScaling- Enable resizing containers without limits

This PR fixes critical bugs in the pod resize code, specifically addressing cases where containers lack resource limits. It ensures proper handling of these scenarios, enabling in-place vertical scaling for such containers. Also, the PR enhances test coverage to prevent regressions, marking a step forward for reliable container resizing in Kubernetes.

KEP of the Week

KEP-3221: Structured Authorization Configuration

Currently, kube-apiserver configures its authorization chain using --authorization-* flags, limiting admins to a single webhook via --authorization-modes. This restricts creating ordered authorization chains with multiple webhooks. This proposal suggests a structured configuration for defining the authorization chain, supporting multiple webhooks with fine-grained controls, including an explicit Deny authorizer.

This KEP is tracked for alpha release in the ongoing v1.32 cycle.

Other Merges

kubectl apply now coerces null values for labels and annotations in manifests to empty string values

Configure watch cache history window based on request timeout

kubectl: improved test coverage for cordon command

Removed the limitation on exposing port 10250 externally in service

kube-proxy extends the schema of metrics/ endpoints to incorporate info about corresponding IP family

Fix for data race in CBOR serializer’s custom marshaler type cache

kubelet: Improvements to reboot event reporting

kubeadm: removed preflight check for ip, iptables, ethtool and tc on Linux nodes

docs: example added for set-based requirement for -l/–selector flag

Drop use of winreadlinkvolume godebug option

kubelet: fix for issue mounting CSI volumes on Windows nodes in 1.32.0 release candidates

Added validation to versioned feature specs

Added kubelet validation for containerLogMaxFiles

scheduler: Renamed UpdatePodTolerations for code style consistency

kubeadm: Fix to not read kubeconfig from disk repeatedly in the init phase

Added a /flagz endpoint for kube-proxy

Adjustments to throughput threshold for new tests based on historical times to avoid flakiness.

Record dataTimestamp from external signers at float granularity

Use autoscalingv2 in kubectl autoscale

DRA: validations for labels in node selectors

Fix for memory leak in kube-proxy EndpointSliceCache

FG:InPlacePodVerticalScaling Remove ResizePolicy defaulting

Use generic sets rather than deprecated sets.String

Test EndpointSlice in dual-stack e2e tests

Fix for linting issue in TestNodeDeletionReleaseCIDR

Cleanup for ServiceChangeTracker and EndpointsChangeTracker

Improvements to validation for missing storedVersion

Documententation added for the existence of nftables as a kube-proxy mode

Fixed kubectl wait –for=create behavior with label selectors

Added non graceful shutdown integration test

Added validation for NodeSelectorRequirement’s values

Fix to prevent unnecessary resolving of iscsi/fc devices

Optionally set the User.UID from an x509 client cert

Fine-grained QHints for interpodaffinity plugin

Allow ContainerResource calculations to continue with missing metrics like Resource calculations

Added warning for duplicate port name definition

Deprecated

Removed support for v1alpha1 version of ValidatingAdmissionPolicy and ValidatingAdmissionPolicyBinding API kinds.

kube-apiserver: inactive serving code is removed for authentication.k8s.io/v1alpha1 APIs

Deprecated pod_scheduling_duration_seconds metric is removed

Version Updates

Bump kubedns and nodelocaldns to 1.24.0

Bump kube-openapi

x/crypto/ssh dependency to v0.31.0

cri-tools to v1.32.0

Update publishing-bot rules to Go 1.22.9

hnslib to v0.0.8

Shoutouts

Big 1.32 Shoutout from Federico Muñoz: With Kubernetes v1.32 out, I want to acknowledge those that made it possible: my Release Lead shadows @Nina Polshakova @Sreeram Venkitesh @Mohammad Reza Saleh @Vyom Yadav, Enhancements Lead @tjons and shadows @Jenny Shu @Sepideh @Dipesh, Release Signal lead @Drew Hagen, and shadows @Amim Knabben @ChengHao Yang (tico88612) @Wendy Ha @sbaumer, Docs lead @dchan, and shadows @anshuman @Rod @James Spurin @Shedrack Akintayo @Michelle Nguyen, Release Notes lead @satyampsoni, and shadows @Augustin Tsang @jefftrojan @Lavish Pal @Melony Q. (aka.cloudmelon ) @rayandas @Sneha, Comms lead @Matteo, and shadows @Edith @Rashan @Ryota @Will-I-Am, Release Managers @jimangel and @Mickey and our EA @Kat Cosgrove (plus @Grace Nguyen from SIG Release). The success of this is much more the result of all your tireless work than anything else.

via Last Week in Kubernetes Development https://lwkd.info/

December 16, 2024 at 05:00PM

What Do I Hate About Kubernetes?

What are the things I dislike about Kubernetes? What should be improved?

kubernetes #k8s

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Contact Chris Short

https://chrisshort.net/contact/

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December 17, 2024 at 07:00PM

Kubernetes 1.32: Moving Volume Group Snapshots to Beta

https://kubernetes.io/blog/2024/12/18/kubernetes-1-32-volume-group-snapshot-beta/

Volume group snapshots were introduced as an Alpha feature with the Kubernetes 1.27 release. The recent release of Kubernetes v1.32 moved that support to beta. The support for volume group snapshots relies on a set of extension APIs for group snapshots. These APIs allow users to take crash consistent snapshots for a set of volumes. Behind the scenes, Kubernetes uses a label selector to group multiple PersistentVolumeClaims for snapshotting. A key aim is to allow you restore that set of snapshots to new volumes and recover your workload based on a crash consistent recovery point.

This new feature is only supported for CSI volume drivers.

An overview of volume group snapshots

Some storage systems provide the ability to create a crash consistent snapshot of multiple volumes. A group snapshot represents copies made from multiple volumes, that are taken at the same point-in-time. A group snapshot can be used either to rehydrate new volumes (pre-populated with the snapshot data) or to restore existing volumes to a previous state (represented by the snapshots).

Why add volume group snapshots to Kubernetes?

The Kubernetes volume plugin system already provides a powerful abstraction that automates the provisioning, attaching, mounting, resizing, and snapshotting of block and file storage.

Underpinning all these features is the Kubernetes goal of workload portability: Kubernetes aims to create an abstraction layer between distributed applications and underlying clusters so that applications can be agnostic to the specifics of the cluster they run on and application deployment requires no cluster specific knowledge.

There was already a VolumeSnapshot API that provides the ability to take a snapshot of a persistent volume to protect against data loss or data corruption. However, there are other snapshotting functionalities not covered by the VolumeSnapshot API.

Some storage systems support consistent group snapshots that allow a snapshot to be taken from multiple volumes at the same point-in-time to achieve write order consistency. This can be useful for applications that contain multiple volumes. For example, an application may have data stored in one volume and logs stored in another volume. If snapshots for the data volume and the logs volume are taken at different times, the application will not be consistent and will not function properly if it is restored from those snapshots when a disaster strikes.

It is true that you can quiesce the application first, take an individual snapshot from each volume that is part of the application one after the other, and then unquiesce the application after all the individual snapshots are taken. This way, you would get application consistent snapshots.

However, sometimes the application quiesce can be so time consuming that you want to do it less frequently, or it may not be possible to quiesce an application at all. For example, a user may want to run weekly backups with application quiesce and nightly backups without application quiesce but with consistent group support which provides crash consistency across all volumes in the group.

Kubernetes APIs for volume group snapshots

Kubernetes' support for volume group snapshots relies on three API kinds that are used for managing snapshots:

VolumeGroupSnapshot

Created by a Kubernetes user (or perhaps by your own automation) to request creation of a volume group snapshot for multiple persistent volume claims. It contains information about the volume group snapshot operation such as the timestamp when the volume group snapshot was taken and whether it is ready to use. The creation and deletion of this object represents a desire to create or delete a cluster resource (a group snapshot).

VolumeGroupSnapshotContent

Created by the snapshot controller for a dynamically created VolumeGroupSnapshot. It contains information about the volume group snapshot including the volume group snapshot ID. This object represents a provisioned resource on the cluster (a group snapshot). The VolumeGroupSnapshotContent object binds to the VolumeGroupSnapshot for which it was created with a one-to-one mapping.

VolumeGroupSnapshotClass

Created by cluster administrators to describe how volume group snapshots should be created, including the driver information, the deletion policy, etc.

These three API kinds are defined as CustomResourceDefinitions (CRDs). These CRDs must be installed in a Kubernetes cluster for a CSI Driver to support volume group snapshots.

What components are needed to support volume group snapshots

Volume group snapshots are implemented in the external-snapshotter repository. Implementing volume group snapshots meant adding or changing several components:

Added new CustomResourceDefinitions for VolumeGroupSnapshot and two supporting APIs.

Volume group snapshot controller logic is added to the common snapshot controller.

Adding logic to make CSI calls into the snapshotter sidecar controller.

The volume snapshot controller and CRDs are deployed once per cluster, while the sidecar is bundled with each CSI driver.

Therefore, it makes sense to deploy the volume snapshot controller and CRDs as a cluster addon.

The Kubernetes project recommends that Kubernetes distributors bundle and deploy the volume snapshot controller and CRDs as part of their Kubernetes cluster management process (independent of any CSI Driver).

What's new in Beta?

The VolumeGroupSnapshot feature in CSI spec moved to GA in the v1.11.0 release.

The snapshot validation webhook was deprecated in external-snapshotter v8.0.0 and it is now removed. Most of the validation webhook logic was added as validation rules into the CRDs. Minimum required Kubernetes version is 1.25 for these validation rules. One thing in the validation webhook not moved to CRDs is the prevention of creating multiple default volume snapshot classes and multiple default volume group snapshot classes for the same CSI driver. With the removal of the validation webhook, an error will still be raised when dynamically provisioning a VolumeSnapshot or VolumeGroupSnapshot when multiple default volume snapshot classes or multiple default volume group snapshot classes for the same CSI driver exist.

The enable-volumegroup-snapshot flag in the snapshot-controller and the CSI snapshotter sidecar has been replaced by a feature gate. Since VolumeGroupSnapshot is a new API, the feature moves to Beta but the feature gate is disabled by default. To use this feature, enable the feature gate by adding the flag --feature-gates=CSIVolumeGroupSnapshot=true when starting the snapshot-controller and the CSI snapshotter sidecar.

The logic to dynamically create the VolumeGroupSnapshot and its corresponding individual VolumeSnapshot and VolumeSnapshotContent objects are moved from the CSI snapshotter to the common snapshot-controller. New RBAC rules are added to the common snapshot-controller and some RBAC rules are removed from the CSI snapshotter sidecar accordingly.

How do I use Kubernetes volume group snapshots

Creating a new group snapshot with Kubernetes

Once a VolumeGroupSnapshotClass object is defined and you have volumes you want to snapshot together, you may request a new group snapshot by creating a VolumeGroupSnapshot object.

The source of the group snapshot specifies whether the underlying group snapshot should be dynamically created or if a pre-existing VolumeGroupSnapshotContent should be used.

A pre-existing VolumeGroupSnapshotContent is created by a cluster administrator. It contains the details of the real volume group snapshot on the storage system which is available for use by cluster users.

One of the following members in the source of the group snapshot must be set.

selector - a label query over PersistentVolumeClaims that are to be grouped together for snapshotting. This selector will be used to match the label added to a PVC.

volumeGroupSnapshotContentName - specifies the name of a pre-existing VolumeGroupSnapshotContent object representing an existing volume group snapshot.

Dynamically provision a group snapshot

In the following example, there are two PVCs.

NAME STATUS VOLUME CAPACITY ACCESS MODES STORAGECLASS VOLUMEATTRIBUTESCLASS AGE pvc-0 Bound pvc-6e1f7d34-a5c5-4548-b104-01e72c72b9f2 100Mi RWO csi-hostpath-sc <unset> 2m15s pvc-1 Bound pvc-abc640b3-2cc1-4c56-ad0c-4f0f0e636efa 100Mi RWO csi-hostpath-sc <unset> 2m7s

Label the PVCs.

% kubectl label pvc pvc-0 group=myGroup persistentvolumeclaim/pvc-0 labeled

% kubectl label pvc pvc-1 group=myGroup persistentvolumeclaim/pvc-1 labeled

For dynamic provisioning, a selector must be set so that the snapshot controller can find PVCs with the matching labels to be snapshotted together.

apiVersion: groupsnapshot.storage.k8s.io/v1beta1 kind: VolumeGroupSnapshot metadata: name: snapshot-daily-20241217 namespace: demo-namespace spec: volumeGroupSnapshotClassName: csi-groupSnapclass source: selector: matchLabels: group: myGroup

In the VolumeGroupSnapshot spec, a user can specify the VolumeGroupSnapshotClass which has the information about which CSI driver should be used for creating the group snapshot. A VolumGroupSnapshotClass is required for dynamic provisioning.

apiVersion: groupsnapshot.storage.k8s.io/v1beta1 kind: VolumeGroupSnapshotClass metadata: name: csi-groupSnapclass annotations: kubernetes.io/description: "Example group snapshot class" driver: example.csi.k8s.io deletionPolicy: Delete

As a result of the volume group snapshot creation, a corresponding VolumeGroupSnapshotContent object will be created with a volumeGroupSnapshotHandle pointing to a resource on the storage system.

Two individual volume snapshots will be created as part of the volume group snapshot creation.

NAME READYTOUSE SOURCEPVC RESTORESIZE SNAPSHOTCONTENT AGE snapshot-0962a745b2bf930bb385b7b50c9b08a