容器存储接口 CSI

Container Storage Interface (CSI) 是从 v1.9 引入的容器存储接口，并于 v1.13 版本正式 GA。实际上，CSI 是整个容器生态的标准存储接口，同样适用于 Mesos、Cloud Foundry 等其他的容器集群调度系统。

版本信息

Kubernetes	CSI Spec	Status
v1.9	v0.1.0	Alpha
v1.10	v0.2.0	Beta
v1.11-v1.12	v0.3.0	Beta
v1.13	v0.3.0, v1.0.0	GA

Kubernetes

CSI Spec

Status

v1.9

v0.1.0

Alpha

v1.10

v0.2.0

Beta

v1.11-v1.12

v0.3.0

Beta

v1.13

v0.3.0, v1.0.0

Sidecar 容器版本

Container Name	Description	CSI spec	Latest Release Tag
external-provisioner	Watch PVC and create PV	v1.0.0	v1.0.1
external-attacher	Operate VolumeAttachment	v1.0.0	v1.0.1
external-snapshotter	Operate VolumeSnapshot	v1.0.0	v1.0.1
node-driver-registrar	Register kubelet plugin	v1.0.0	v1.0.2
cluster-driver-registrar	Register CSIDriver Object	v1.0.0	v1.0.1
livenessprobe	Monitors health of CSI driver	v1.0.0	v1.0.2

Container Name

Description

CSI spec

Latest Release Tag

external-provisioner

Watch PVC and create PV

v1.0.0

v1.0.1

external-attacher

Operate VolumeAttachment

v1.0.0

v1.0.1

external-snapshotter

Operate VolumeSnapshot

v1.0.0

v1.0.1

node-driver-registrar

v1.0.0

v1.0.2

cluster-driver-registrar

v1.0.0

v1.0.1

livenessprobe

Monitors health of CSI driver

v1.0.0

v1.0.2

原理

类似于 CRI，CSI 也是基于 gRPC 实现。详细的 CSI SPEC 可以参考这里，它要求插件开发者要实现三个 gRPC 服务：

Identity Service：用于 Kubernetes 与 CSI 插件协调版本信息
Controller Service：用于创建、删除以及管理 Volume 存储卷
Node Service：用于将 Volume 存储卷挂载到指定的目录中以便 Kubelet 创建容器时使用（需要监听在 /var/lib/kubelet/plugins/[SanitizedCSIDriverName]/csi.sock）

由于 CSI 监听在 unix socket 文件上， kube-controller-manager 并不能直接调用 CSI 插件。为了协调 Volume 生命周期的管理，并方便开发者实现 CSI 插件，Kubernetes 提供了几个 sidecar 容器并推荐使用下述方法来部署 CSI 插件：

该部署方法包括：

StatefuelSet：副本数为 1 保证只有一个实例运行，它包含三个容器
- 用户实现的 CSI 插件
- External Attacher：Kubernetes 提供的 sidecar 容器，它监听 VolumeAttachment 和 PersistentVolume 对象的变化情况，并调用 CSI 插件的 ControllerPublishVolume 和 ControllerUnpublishVolume 等 API 将 Volume 挂载或卸载到指定的 Node 上
- External Provisioner：Kubernetes 提供的 sidecar 容器，它监听 PersistentVolumeClaim 对象的变化情况，并调用 CSI 插件的 ControllerPublish 和 ControllerUnpublish 等 API 管理 Volume
Daemonset：将 CSI 插件运行在每个 Node 上，以便 Kubelet 可以调用。它包含 2 个容器
- 用户实现的 CSI 插件
- Driver Registrar：注册 CSI 插件到 kubelet 中，并初始化 NodeId（即给 Node 对象增加一个 Annotation csi.volume.kubernetes.io/nodeid）

配置

API Server 配置：

--allow-privileged=true
--feature-gates=CSIPersistentVolume=true,MountPropagation=true
--runtime-config=storage.k8s.io/v1alpha1=true

Controller-manager 配置：

--feature-gates=CSIPersistentVolume=true

Kubelet 配置：

--allow-privileged=true
--feature-gates=CSIPersistentVolume=true,MountPropagation=true

示例

Kubernetes 提供了几个 CSI 示例，包括 NFS、ISCSI、HostPath、Cinder 以及 FlexAdapter 等。在实现 CSI 插件时，这些示例可以用作参考。

Name	Status	More Information
Cinder	v0.2.0	A Container Storage Interface (CSI) Storage Plug-in for Cinder
DigitalOcean Block Storage	v0.0.1 (alpha)	A Container Storage Interface (CSI) Driver for DigitalOcean Block Storage
AWS Elastic Block Storage	v0.0.1(alpha)	A Container Storage Interface (CSI) Driver for AWS Elastic Block Storage (EBS)
GCE Persistent Disk	Alpha	A Container Storage Interface (CSI) Storage Plugin for Google Compute Engine Persistent Disk
OpenSDS	Beta	For more information, please visit releases and https://github.com/opensds/nbp/tree/master/csi
Portworx	0.2.0	CSI implementation is available here which can be used as an example also.
RBD	v0.2.0	A Container Storage Interface (CSI) Storage RBD Plug-in for Ceph
CephFS	v0.2.0	A Container Storage Interface (CSI) Storage Plug-in for CephFS
ScaleIO	v0.1.0	A Container Storage Interface (CSI) Storage Plugin for DellEMC ScaleIO
vSphere	v0.1.0	A Container Storage Interface (CSI) Storage Plug-in for VMware vSphere
NetApp	v0.2.0 (alpha)	A Container Storage Interface (CSI) Storage Plug-in for NetApp's Trident container storage orchestrator
Ember CSI	v0.2.0 (alpha)	Multi-vendor CSI plugin supporting over 80 storage drivers to provide block and mount storage to Container Orchestration systems.
Nutanix	beta	A Container Storage Interface (CSI) Storage Driver for Nutanix
Quobyte	v0.2.0	A Container Storage Interface (CSI) Plugin for Quobyte

Name

Status

More Information

Cinder

v0.2.0

A Container Storage Interface (CSI) Storage Plug-in for Cinder

DigitalOcean Block Storage

v0.0.1 (alpha)

A Container Storage Interface (CSI) Driver for DigitalOcean Block Storage

AWS Elastic Block Storage

v0.0.1(alpha)

A Container Storage Interface (CSI) Driver for AWS Elastic Block Storage (EBS)

GCE Persistent Disk

Alpha

A Container Storage Interface (CSI) Storage Plugin for Google Compute Engine Persistent Disk

OpenSDS

Beta

For more information, please visit releases and https://github.com/opensds/nbp/tree/master/csi

Portworx

0.2.0

CSI implementation is available here which can be used as an example also.

RBD

v0.2.0

A Container Storage Interface (CSI) Storage RBD Plug-in for Ceph

CephFS

v0.2.0

A Container Storage Interface (CSI) Storage Plug-in for CephFS

ScaleIO

v0.1.0

A Container Storage Interface (CSI) Storage Plugin for DellEMC ScaleIO

vSphere

v0.1.0

A Container Storage Interface (CSI) Storage Plug-in for VMware vSphere

NetApp

v0.2.0 (alpha)

A Container Storage Interface (CSI) Storage Plug-in for NetApp's Trident container storage orchestrator

Ember CSI

v0.2.0 (alpha)

Multi-vendor CSI plugin supporting over 80 storage drivers to provide block and mount storage to Container Orchestration systems.

Nutanix

beta

A Container Storage Interface (CSI) Storage Driver for Nutanix

Quobyte

v0.2.0

A Container Storage Interface (CSI) Plugin for Quobyte

下面以 NFS 为例来看一下 CSI 插件的使用方法。

首先需要部署 NFS 插件：

git clone https://github.com/kubernetes-csi/drivers
cd drivers/pkg/nfs
kubectl create -f deploy/kubernetes

然后创建一个使用 NFS 存储卷的容器

kubectl create -f examples/kubernetes/nginx.yaml

该例中已直接创建 PV 的方式使用 NFS

apiVersion: v1
kind: PersistentVolume
metadata:
  name: data-nfsplugin
  labels:
    name: data-nfsplugin
  annotations:
    csi.volume.kubernetes.io/volume-attributes: '{"server":"10.10.10.10","share":"share"}'
spec:
  accessModes:
  - ReadWriteOnce
  capacity:
    storage: 100Gi
  csi:
    driver: csi-nfsplugin
    volumeHandle: data-id
---
apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: data-nfsplugin
spec:
  accessModes:
  - ReadWriteOnce
  resources:
    requests:
      storage: 100Gi
  selector:
    matchExpressions:
    - key: name
      operator: In
      values: ["data-nfsplugin"]

也可以用在 StorageClass 中

kind: StorageClass
apiVersion: storage.k8s.io/v1
metadata:
  name: csi-sc-nfsplugin
provisioner: csi-nfsplugin
parameters:

---
apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: request-for-storage
spec:
  accessModes:
  - ReadWriteOnce
  resources:
    requests:
      storage: 5Gi
  storageClassName: csi-sc-nfsplugin

参考文档

最后更新于1年前