从 OKR 部署中获得的 7 项关键经验(从前慢)
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2022-05-29
Kubernetes 是什么
Kubernetes 是一个开源的,用于管理云平台中多个主机上的容器化的应用,Kubernetes 的目标是让部署容器化的应用简单并且高效,Kubernetes 提供了应用部署,规划,更新,维护的一种机制。
Kubernetes 在设计结构上定义了一系列的构建模块,其目的是为了提供一个可以部署、维护和扩展应用程序的机制,组成 Kubernetes 的组件设计概念为松耦合和可扩展的,这样可以使之满足多种不同的工作负载。可扩展性在很大程度上由 Kubernetes
API 提供,此 API 主要被作为扩展的内部组件以及 Kubernetes 上运行的容器来使用。
Kubernetes 主要由以下几个核心组件组成:
etcd 保存了整个集群的状态
apiserver 提供了资源操作的唯一入口,并提供认证、授权、访问控制、API注册和发现等机制
controller manager 负责维护集群的状态,比如故障检测、自动扩展、滚动更新等
scheduler 负责资源的调度,按照预定的调度策略将Pod调度到相应的机器上
kubelet 负责维护容器的生命周期,同时也负责 Volume和网络的管理
Container runtime 负责镜像管理以及 Pod 和容器的真正运行(CRI)
kube-proxy 负责为 Service 提供 cluster 内部的服务发现和负载均衡
除了核心组件,还有一些推荐的 Add-ons:
kube-dns 负责为整个集群提供 DNS 服务
Ingress Controller 为服务提供外网入口
Heapster 提供资源监控
Dashboard 提供 GUI
Federation 提供跨可用区的集群
Fluentd-elasticsearch 提供集群日志采集、存储与查询
Kubernetes 和数据库
数据库容器化是最近的一大热点,那么 Kubernetes 能为数据库带来什么好处呢?
故障恢复: Kubernetes 提供故障恢复的功能,数据库应用如果宕掉,Kubernetes 可以将其自动重启,或者将数据库实例迁移到集群中其他节点上
存储管理: Kubernetes 提供了丰富的存储接入方案,数据库应用能透明地使用不同类型的存储系统
负载均衡: Kubernetes Service 提供负载均衡功能,能将外部访问平摊给不同的数据库实例副本上
水平拓展: Kubernetes 可以根据当前数据库集群的资源利用率情况,缩放副本数目,从而提升资源的利用率
目前很多数据库,如:MySQL,MongoDB 和 TiDB 在 Kubernetes 集群中都能运行很良好。
Nebula Graph在Kubernetes中的实践
Nebula Graph 是一个分布式的开源图数据库,主要组件有:Query Engine 的 graphd,数据存储的 storaged,和元数据的 meted。在 Kubernetes 实践过程中,它主要给图数据库 Nebula Graph 带来了以下的好处:
Kubernetes 能分摊 nebula graphd,metad 和 storaged 不副本之间的负载。graphd,metad 和 storaged 可以通过 Kubernetes 的域名服务自动发现彼此。
通过 storageclass,pvc 和 pv 可以屏蔽底层存储细节,无论使用本地卷还是云盘,Kubernetes 均可以屏蔽这些细节。
通过 Kubernetes 可以在几秒内成功部署一套 Nebula 集群,Kubernetes 也可以无感知地实现 Nebula 集群的升级。
Nebula 集群通过 Kubernetes 可以做到自我恢复,单体副本 crash,Kubernetes 可以重新将其拉起,无需运维人员介入。
Kubernetes 可以根据当前 Nebula 集群的资源利用率情况水平伸缩 Nebula 集群,从而提供集群的性能。
下面来讲解下具体的实践内容。
集群部署
这里主要罗列下本文部署涉及到的机器、操作系统参数
操作系统使用的 CentOS-7.6.1810 x86_64
虚拟机配置
4 CPU
8G 内存
50G 系统盘
50G 数据盘A
50G 数据盘B
Kubernetes 集群版本 v1.16
Nebula 版本为 v1.0.0-rc3
使用本地 PV 作为数据存储
以下为集群清单
安装 Helm
准备本地磁盘,并安装本地卷插件
安装 nebula 集群
安装 ingress-controller
安装 Helm
Helm 是 Kubernetes 集群上的包管理工具,类似 CentOS 上的 yum,Ubuntu 上的 apt-get。使用 Helm 可以极大地降低使用 Kubernetes 部署应用的门槛。由于本篇文章不做 Helm 详细介绍,有兴趣的小伙伴可自行阅读《Helm 入门指南》
使用下面命令在终端执行即可安装 Helm
[root@nebula ~]# wget https://get.helm.sh/helm-v3.0.1-linux-amd64.tar.gz [root@nebula ~]# tar -zxvf helm/helm-v3.0.1-linux-amd64.tgz[root@nebula ~]# mv linux-amd64/helm /usr/bin/helm[root@nebula ~]# chmod +x /usr/bin/helm
执行 helm version 命令即可查看对应的 Helm 版本,以文本为例,以下为输出结果:
version.BuildInfo{ Version:"v3.0.1", GitCommit:"7c22ef9ce89e0ebeb7125ba2ebf7d421f3e82ffa", GitTreeState:"clean", GoVersion:"go1.13.4"}
设置本地磁盘
在每台机器上做如下配置
[root@nebula ~]# sudo mkdir -p /mnt/disks
[root@nebula ~]# sudo mkfs.ext4 /dev/diskA [root@nebula ~]# sudo mkfs.ext4 /dev/diskB
[root@nebula ~]# DISKA_UUID=$(blkid -s UUID -o value /dev/diskA) [root@nebula ~]# DISKB_UUID=$(blkid -s UUID -o value /dev/diskB) [root@nebula ~]# sudo mkdir /mnt/disks/$DISKA_UUID[root@nebula ~]# sudo mkdir /mnt/disks/$DISKB_UUID[root@nebula ~]# sudo mount -t ext4 /dev/diskA /mnt/disks/$DISKA_UUID[root@nebula ~]# sudo mount -t ext4 /dev/diskB /mnt/disks/$DISKB_UUID[root@nebula ~]# echo UUID=`sudo blkid -s UUID -o value /dev/diskA` /mnt/disks/$DISKA_UUID ext4 defaults 0 2 | sudo tee -a /etc/fstab[root@nebula ~]# echo UUID=`sudo blkid -s UUID -o value /dev/diskB` /mnt/disks/$DISKB_UUID ext4 defaults 0 2 | sudo tee -a /etc/fstab
部署本地卷插件
[root@nebula ~]# curl https://github.com/kubernetes-sigs/sig-storage-local-static-provisioner/archive/v2.3.3.zip[root@nebula ~]# unzip v2.3.3.zip
修改 v2.3.3/helm/provisioner/values.yaml
## Common options.#common: # # Defines whether to generate service account and role bindings. # rbac: true # # Defines the namespace where provisioner runs # namespace: default # # Defines whether to create provisioner namespace # createNamespace: false # # Beta PV.NodeAffinity field is used by default. If running against pre-1.10 # k8s version, the `useAlphaAPI` flag must be enabled in the configMap. # useAlphaAPI: false # # Indicates if PVs should be dependents of the owner Node. # setPVOwnerRef: false # # Provisioner clean volumes in process by default. If set to true, provisioner # will use Jobs to clean. # useJobForCleaning: false # # Provisioner name contains Node.UID by default. If set to true, the provisioner # name will only use Node.Name. # useNodeNameOnly: false # # Resync period in reflectors will be random between minResyncPeriod and # 2*minResyncPeriod. Default: 5m0s. # #minResyncPeriod: 5m0s # # Defines the name of configmap used by Provisioner # configMapName: "local-provisioner-config" # # Enables or disables Pod Security Policy creation and binding # podSecurityPolicy: false## Configure storage classes.#classes:- name: fast-disks # Defines name of storage classe. # Path on the host where local volumes of this storage class are mounted # under. hostDir: /mnt/fast-disks # Optionally specify mount path of local volumes. By default, we use same # path as hostDir in container. # mountDir: /mnt/fast-disks # The volume mode of created PersistentVolume object. Default to Filesystem # if not specified. volumeMode: Filesystem # Filesystem type to mount. # It applies only when the source path is a block device, # and desire volume mode is Filesystem. # Must be a filesystem type supported by the host operating system. fsType: ext4 blockCleanerCommand: # Do a quick reset of the block device during its cleanup. # - "/scripts/quick_reset.sh" # or use dd to zero out block dev in two iterations by uncommenting these lines # - "/scripts/dd_zero.sh" # - "2" # or run shred utility for 2 iteration.s - "/scripts/shred.sh" - "2" # or blkdiscard utility by uncommenting the line below. # - "/scripts/blkdiscard.sh" # Uncomment to create storage class object with default configuration. # storageClass: true # Uncomment to create storage class object and configure it. # storageClass: # reclaimPolicy: Delete # Available reclaim policies: Delete/Retain, defaults: Delete. # isDefaultClass: true # set as default class## Configure DaemonSet for provisioner.#daemonset: # # Defines the name of a Provisioner # name: "local-volume-provisioner" # # Defines Provisioner's image name including container registry. # image: quay.io/external_storage/local-volume-provisioner:v2.3.3 # # Defines Image download policy, see kubernetes documentation for available values. # #imagePullPolicy: Always # # Defines a name of the service account which Provisioner will use to communicate with API server. # serviceAccount: local-storage-admin # # Defines a name of the Pod Priority Class to use with the Provisioner DaemonSet # # Note that if you want to make it critical, specify "system-cluster-critical" # or "system-node-critical" and deploy in kube-system namespace. # Ref: https://k8s.io/docs/tasks/administer-cluster/guaranteed-scheduling-critical-addon-pods/#marking-pod-as-critical # #priorityClassName: system-node-critical # If configured, nodeSelector will add a nodeSelector field to the DaemonSet PodSpec. # # NodeSelector constraint for local-volume-provisioner scheduling to nodes. # Ref: https://kubernetes.io/docs/concepts/configuration/assign-pod-node/#nodeselector nodeSelector: {} # # If configured KubeConfigEnv will (optionally) specify the location of kubeconfig file on the node. # kubeConfigEnv: KUBECONFIG # # List of node labels to be copied to the PVs created by the provisioner in a format: # # nodeLabels: # - failure-domain.beta.kubernetes.io/zone # - failure-domain.beta.kubernetes.io/region # # If configured, tolerations will add a toleration field to the DaemonSet PodSpec. # # Node tolerations for local-volume-provisioner scheduling to nodes with taints. # Ref: https://kubernetes.io/docs/concepts/configuration/taint-and-toleration/ tolerations: [] # # If configured, resources will set the requests/limits field to the Daemonset PodSpec. # Ref: https://kubernetes.io/docs/concepts/configuration/manage-compute-resources-container/ resources: {}## Configure Prometheus monitoring#prometheus: operator: ## Are you using Prometheus Operator? enabled: false serviceMonitor: ## Interval at which Prometheus scrapes the provisioner interval: 10s # Namespace Prometheus is installed in namespace: monitoring ## Defaults to whats used if you follow CoreOS [Prometheus Install Instructions](https://github.com/coreos/prometheus-operator/tree/master/helm#tldr) ## [Prometheus Selector Label](https://github.com/coreos/prometheus-operator/blob/master/helm/prometheus/templates/prometheus.yaml#L65) ## [Kube Prometheus Selector Label](https://github.com/coreos/prometheus-operator/blob/master/helm/kube-prometheus/values.yaml#L298) selector: prometheus: kube-prometheus
将hostDir: /mnt/fast-disks 改成hostDir: /mnt/disks
将# storageClass: true 改成 storageClass: true
然后执行:
#安装[root@nebula ~]# helm install local-static-provisioner v2.3.3/helm/provisioner#查看local-static-provisioner部署情况[root@nebula ~]# helm list
部署 nebula 集群
# 下载nebula[root@nebula ~]# wget https://github.com/vesoft-inc/nebula/archive/master.zip # 解压[root@nebula ~]# unzip master.zip
下面是 Kubernetes 节点列表,我们需要设置 slave 节点的调度标签。可以将 _192.168.0.2_,_192.168.0.3_,_192.168.0.4_ 打上 nebula: "yes" 的标签。
具体操作如下:
[root@nebula ~]# kubectl label node 192.168.0.2 nebula="yes" --overwrite [root@nebula ~]# kubectl label node 192.168.0.3 nebula="yes" --overwrite[root@nebula ~]# kubectl label node 192.168.0.4 nebula="yes" --overwrite
nebula helm-chart 包目录如下:
master/kubernetes/ └── helm ├── Chart.yaml ├── templates │ ├── configmap.yaml │ ├── deployment.yaml │ ├── _helpers.tpl │ ├── ingress-configmap.yaml\ │ ├── NOTES.txt │ ├── pdb.yaml │ ├── service.yaml │ └── statefulset.yaml └── values.yaml 2 directories, 10 files
我们需要调整 master/kubernetes/values.yaml 里面的 MetadHosts 的值,将这个 IP List 替换本环境的 3 个 k8s worker 的 ip。
MetadHosts: - 192.168.0.2:44500 - 192.168.0.3:44500 - 192.168.0.4:44500
# 安装[root@nebula ~]# helm install nebula master/kubernetes/helm # 查看[root@nebula ~]# helm status nebula# 查看k8s集群上nebula部署情况[root@nebula ~]# kubectl get pod | grep nebulanebula-graphd-579d89c958-g2j2c 1/1 Running 0 1m nebula-graphd-579d89c958-p7829 1/1 Running 0 1m nebula-graphd-579d89c958-q74zx 1/1 Running 0 1m nebula-metad-0 1/1 Running 0 1m nebula-metad-1 1/1 Running 0 1m nebula-metad-2 1/1 Running 0 1m nebula-storaged-0 1/1 Running 0 1m nebula-storaged-1 1/1 Running 0 1m nebula-storaged-2 1/1 Running 0 1m
部署 Ingress-controller
Ingress-controller 是 Kubernetes 的一个 Add-Ons。Kubernetes 通过 ingress-controller 将 Kubernetes 内部署的服务暴露给外部用户访问。Ingress-controller 还提供负载均衡的功能,可以将外部访问流量平摊给 k8s 中应用的不同的副本。
选择一个节点部署 Ingress-controller
[root@nebula ~]# kubectl get node NAME STATUS ROLES AGE VERSION 192.168.0.1 Ready master 82d v1.16.1 192.168.0.2 Ready
编写 ingress-nginx.yaml 部署文件
apiVersion: v1 kind: Namespace metadata: name: ingress-nginx labels: app.kubernetes.io/name: ingress-nginx app.kubernetes.io/part-of: ingress-nginx --- kind: ConfigMap apiVersion: v1 metadata: name: nginx-configuration namespace: ingress-nginx labels: app.kubernetes.io/name: ingress-nginx app.kubernetes.io/part-of: ingress-nginx --- kind: ConfigMap apiVersion: v1 metadata: name: tcp-services namespace: ingress-nginx labels: app.kubernetes.io/name: ingress-nginx app.kubernetes.io/part-of: ingress-nginx --- kind: ConfigMap apiVersion: v1 metadata: name: udp-services namespace: ingress-nginx labels: app.kubernetes.io/name: ingress-nginx app.kubernetes.io/part-of: ingress-nginx --- apiVersion: v1 kind: ServiceAccount metadata: name: nginx-ingress-serviceaccount namespace: ingress-nginx labels: app.kubernetes.io/name: ingress-nginx app.kubernetes.io/part-of: ingress-nginx --- apiVersion: rbac.authorization.k8s.io/v1beta1 kind: ClusterRole metadata: name: nginx-ingress-clusterrole labels: app.kubernetes.io/name: ingress-nginx app.kubernetes.io/part-of: ingress-nginx rules: - apiGroups: - "" resources: - configmaps - endpoints - nodes - pods - secrets verbs: - list - watch - apiGroups: - "" resources: - nodes verbs: - get - apiGroups: - "" resources: - services verbs: - get - list - watch - apiGroups: - "extensions" - "networking.k8s.io" resources: - ingresses verbs: - get - list - watch - apiGroups: - "" resources: - events verbs: - create - patch - apiGroups: - "extensions" - "networking.k8s.io" resources: - ingresses/status verbs: - update --- apiVersion: rbac.authorization.k8s.io/v1beta1 kind: Role metadata: name: nginx-ingress-role namespace: ingress-nginx labels: app.kubernetes.io/name: ingress-nginx app.kubernetes.io/part-of: ingress-nginx rules: - apiGroups: - "" resources: - configmaps - pods - secrets - namespaces verbs: - get - apiGroups: - "" resources: - configmaps resourceNames: # Defaults to "
部署 ingress-nginx
# 部署[root@nebula ~]# kubectl create -f ingress-nginx.yaml# 查看部署情况[root@nebula ~]# kubectl get pod -n ingress-nginx NAME READY STATUS RESTARTS AGE nginx-ingress-controller-mmms7 1/1 Running 2 1m
访问 nebula 集群
查看 ingress-nginx 所在的节点:
[root@nebula ~]# kubectl get node -l ingress=yes -owide NAME STATUS ROLES AGE VERSION INTERNAL-IP EXTERNAL-IP OS-IMAGE KERNEL-VERSION CONTAINER-RUNTIME 192.168.0.4 Ready
访问 nebula 集群:
[root@nebula ~]# docker run --rm -ti --net=host vesoft/nebula-console:nightly --addr=192.168.0.4 --port=3699
FAQ
搭建高可用的 Kubernetes 可以参考社区文档:https://kubernetes.io/docs/setup/production-environment/tools/kubeadm/high-availability/
你也可以通过 minikube 搭建本地的 Kubernetes 集群,参考文档:https://kubernetes.io/docs/setup/learning-environment/minikube/
在使用 helm install 时,使用 --set 可以设置部署参数,从而覆盖掉 helm chart 中 values.yaml 中的变量。参考文档:https://helm.sh/docs/intro/using_helm/
使用kubectl get pod | grep nebula命令,或者直接在 Kubernetes dashboard 上查看 nebula 集群的运行状况。
参考文档:https://kubernetes.io/zh/docs/concepts/storage/storage-classes/
参考资料
Helm 入门指南
详解 k8s 组件 Ingress 边缘路由器并落地到微服务
附录
Nebula Graph:一个开源的分布式图数据库
GitHub:https://github.com/vesoft-inc/nebula
知乎:zhihu.com/org/nebulagraph/posts
微博:weibo.com/nebulagraph
存储 Kubernetes
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