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Kubernetes version docking object storage

2022-07-24 15:37:00 【InfoQ】

Object storage

Want to create PersistentVolume（PV）/PersistentVolumeClaim（PVC）, And use cloud object storage to mount data volumes for workloads COS

For object storage , stay k8s There is no need for PV/PVC To do resource abstraction , Applications can directly access and use , If you need to k8s Support access , It's going to take a corresponding csi plug-in unit , Support object storage to file storage, such as ： The way of several big factories, Ali ：https://help.aliyun.com/document_detail/130911.html tencent ：https://cloud.tencent.com/document/product/457/44232 Huawei ：https://support.huaweicloud.com/intl/zh-cn/usermanual-cce/cce_01_0267.html

If the docking file is stored , You can use S3fs You can put Bucket Mount as a folder to Linux Inside the system , Use as a system folder .

Community programs

programme 1：Object Storage API (COSI)

Currently in development , immature

Official documents
https://container-object-storage-interface.github.io/docs/
https://container-object-storage-interface.github.io/
https://github.com/kubernetes/enhancements/tree/master/keps/sig-storage/1979-object-storage-support#provisionergetinfo
Kubernetes v1.23 Official release , What are the enhancements ？

Kubernetes Now it has better extended support for file and block storage (CSI), But these do not support object storage very well , Here's why ：

oss In barrels (bucket) To organize and allocate storage units instead of file system mounts or block devices

oss Services are accessed through network calls, not locally POSIX call

oss No trial csi Defined Attach/Detach Logic ( No need to mount / uninstall )

COSI It's about how to container workloads (Pod) Provide object storage services (oss) Standard agreement for . And csi and cni similar ,Kubernetes It aims to communicate with third parties by defining some standard interfaces oss Service provider decoupling .

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programme 2：csi-s3

have access to , But more testing is needed

Official documents
https://github.com/CTrox/csi-s3
https://github.com/majst01/csi-driver-s3
Use s3(minio) by kubernetes Provide pv Storage

Kubernetes requirement

Kubernetes 1.13+（CSI v1.0.0 Compatibility ）

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Kubernetes Privilege containers must be allowed
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Docker Daemons must allow shared mounts （systemd sign
MountFlags=shared
）

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It's very experimental , Not yet used in any production environment . According to the mounting procedure and S3 Storage back end , Unexpected data loss may occur .
</font>

MountFlags

stay 18.09 Previous Docker In the version ,containerd from Docker Engine daemon management .

stay Docker Engine 18.09 in ,containerd from systemd management . because containerd from systemd management , So anything

docker.service

Change the of Mount settings systemd Custom configuration （ for example ,

MountFlags=slave

） Will destroy Docker Engine Daemons and containerd Interaction between , And you will not be able to start the container .

Run the following command to get Of

MountFlags

Current value of property

docker.service

：

$ sudo systemctl show --property=MountFlags docker.service
MountFlags=

If this command is Print non null values , Please update your configuration

MountFlags

, And then restart it docker service .

Why would you S3 Mount to... In the form of file storage Kubernetes platform ?

For applications that used to use local directories to access data , For example, an application system that uses a local disk or a network shared disk to save data , If the user wants to put the data in S3 On , You need to modify the data access method , For example, modify to use SDK or CLI visit S3 Data stored in .

At the same time to realize kubernetes Cluster is the demand of many users , Whether using managed services or self built kubernetes colony , Storage is kubernetes The focus of cluster construction . also docker The deployment method also allows clients to reduce their dependence on the underlying environment . In order to enable users to use the original application system directly without modification S3 service ,

Need to put S3 The bucket is mounted to the user as a directory kubernetes In the cluster worker Node

utilize S3fs take S3 The storage bucket is kubernetes On the platform
sidecar
How to mount to kubernetes Clustered worker Example of pod in , After mounting, you need to read and write the contents of this bucket pod Can read and write to this bucket , To realize the shared storage function .

What is? S3FS ？

S3fs Is based on FUSE File system

, allow Linux and Mac Os X mount S3 Of the buckets in the local file system ,S3fs Be able to keep the original format of the object ,S3FS yes POSIX A large subset of , Including reading / Writing documents 、 Catalog 、 A symbolic link 、 Pattern 、uid/gid And extended properties ,

And

AmazonS3、Google Cloud storage and others

be based on S3 Object storage compatibility

. About S3fs Detailed introduction , Please see the ：https://github.com/s3fs-fuse/s3fs-fuse