简介:本文侧重介绍了通过 ACK One 的多集群应用分发功能,可以帮助企业管理多集群环境,通过多集群主控示例提供的统一的应用下发入口,实现应用的多集群分发,差异化配置,工作流管理等分发策略。结合 GTM 全局流量管理,快速搭建管理两地三中心的应用容灾系统。
作者:宇汇,壮怀,先河
概述
两地三中心是指在两个城市部署三个业务处理中心,即:生产中心、同城容灾中心、异地容灾中心。在一个城市部署 2 套环境形成同城双中心,同时处理业务并通过高速链路实现数据同步,可切换运行。在另一城市部署1套环境做异地灾备中心,做数据备份,当双中心同时故障时,异地灾备中心可切换处理业务。两地三中心容灾方案可以极大程度的保证业务的连续运行。
使用 ACK One 的多集群管理应用分发功能,可以帮助企业统一管理 3 个 K8s 集群,实现应用在 3 个 K8s 集群快速部署升级,同时实现应用在 3 个 K8s 集群上的差异化配置。配合使用 GTM(全局流量管理)可以实现在故障发生时业务流量在 3 个 K8s 集群的自动切换。对 RDS 数据层面的数据复制,本实践不做具体介绍,可参考 DTS 数据传输服务。
方案架构
前提条件
开启多集群管理主控实例[1]
通过管理关联集群[2],添加 3 个 K8s 集群到主控实例中,构建两地三中心。本实践中,作为示例,在北京部署 2 个 K8s 集群(cluster1-beijing 和 cluster2-beijing),在杭州部署 1 个 K8s 集群(cluster1-hangzhou)。
创建 GTM 实例[3]
应用部署
通过 ACK One 主控实例的应用分发功能[4],在 3 个 K8s 集群中分发应用。对比传统的脚本部署,使用 ACK One 的应用分发可获得如下收益。
本实践中,示例应用为 web 应用,包含 K8s Deployment/Service/Ingress/Configmap 资源,Service/Ingress 对外暴露服务,Deployment 读取 Configmap 中的配置参数。通过创建应用分发规则,将应用分发到 3 个 K8s 集群,包括 2 个北京集群,1 个杭州集群,实现两地三中心。分发过程中对 deployment 和 configmap 资源做差异化配置,以适应不用地点的集群,同时分发过程实现人工审核的灰度控制,限制错误的爆炸半径。
- 执行一下命令创建命名空间 demo。
kubectl create namespace demo
- 使用以下内容,创建 app-meta.yaml 文件。
apiVersion: apps/v1
kind: Deployment
metadata:
labels:
app: web-demo
name: web-demo
namespace: demo
spec:
replicas: 5
selector:
matchLabels:
app: web-demo
template:
metadata:
labels:
app: web-demo
spec:
containers:
- image: acr-multiple-clusters-registry.cn-hangzhou.cr.aliyuncs.com/ack-multiple-clusters/web-demo:0.4.0
name: web-demo
env:
- name: ENV_NAME
value: cluster1-beijing
volumeMounts:
- name: config-file
mountPath: "/config-file"
readOnly: true
volumes:
- name: config-file
configMap:
items:
- key: config.json
path: config.json
name: web-demo
---
apiVersion: v1
kind: Service
metadata:
name: web-demo
namespace: demo
labels:
app: web-demo
spec:
selector:
app: web-demo
ports:
- protocol: TCP
port: 80
targetPort: 8080
---
apiVersion: networking.k8s.io/v1
kind: Ingress
metadata:
name: web-demo
namespace: demo
labels:
app: web-demo
spec:
rules:
- host: web-demo.example.com
http:
paths:
- path: /
pathType: Prefix
backend:
service:
name: web-demo
port:
number: 80
---
apiVersion: v1
kind: ConfigMap
metadata:
name: web-demo
namespace: demo
labels:
app: web-demo
data:
config.json: |
{
database-host: "beijing-db.pg.aliyun.com"
}
- 执行以下命令,在主控实例上部署应用 web-demo。注意:在主控实例上创建 kube 资源并不会下发到子集群,此 kube 资源作为原数据,被后续 Application(步骤 4b)中引用。
kubectl apply -f app-meta.yaml
- 创建应用分发规则。
a. 执行以下命令,查看主控实例管理的关联集群,确定应用的分发目标
kubectl amc get managedcluster
预期输出:
Name Alias HubAccepted
managedcluster-cxxx cluster1-hangzhou true
managedcluster-cxxx cluster2-beijing true
managedcluster-cxxx cluster1-beijing true
b. 使用以下内容,创建应用分发规则 app.yaml。替换示例中的和 managedcluster-cxxx 为实际待发布集群名称。分发规则定义的最佳实践在注释中说明。
在 app.yaml 中,包含以下资源类型:Policy (type:topology) 分发目标,Policy (type: override)差异化规则, Workflow 工作流,Application 应用。具体可参考:应用复制分发[5]、应用分发差异化配置[6]和应用集群间灰度分发[7]。
apiVersion: core.oam.dev/v1alpha1
kind: Policy
metadata:
name: cluster1-beijing
namespace: demo
type: topology
properties:
clusters: [""] #分发目标集群1 cluster1-beijing
---
apiVersion: core.oam.dev/v1alpha1
kind: Policy
metadata:
name: cluster2-beijing
namespace: demo
type: topology
properties:
clusters: [""] #分发目标集群2 cluster2-beijing
---
apiVersion: core.oam.dev/v1alpha1
kind: Policy
metadata:
name: cluster1-hangzhou
namespace: demo
type: topology
properties:
clusters: [""] #分发目标集群3 cluster1-hangzhou
---
apiVersion: core.oam.dev/v1alpha1
kind: Policy
metadata:
name: override-env-cluster2-beijing
namespace: demo
type: override
properties:
components:
- name: "deployment"
traits:
- type: env
properties:
containerName: web-demo
env:
ENV_NAME: cluster2-beijing #对集群cluster2-beijing的deployment做环境变量的差异化配置
---
apiVersion: core.oam.dev/v1alpha1
kind: Policy
metadata:
name: override-env-cluster1-hangzhou
namespace: demo
type: override
properties:
components:
- name: "deployment"
traits:
- type: env
properties:
containerName: web-demo
env:
ENV_NAME: cluster1-hangzhou #对集群cluster1-hangzhou的deployment做环境变量的差异化配置
---
apiVersion: core.oam.dev/v1alpha1
kind: Policy
metadata:
name: override-replic-cluster1-hangzhou
namespace: demo
type: override
properties:
components:
- name: "deployment"
traits:
- type: scaler
properties:
replicas: 1 #对集群cluster1-hangzhou的deployment做副本数的差异化配置
---
apiVersion: core.oam.dev/v1alpha1
kind: Policy
metadata:
name: override-configmap-cluster1-hangzhou
namespace: demo
type: override
properties:
components:
- name: "configmap"
traits:
- type: json-merge-patch #对集群cluster1-hangzhou的deployment做configmap的差异化配置
properties:
data:
config.json: |
{
database-address: "hangzhou-db.pg.aliyun.com"
}
---
apiVersion: core.oam.dev/v1alpha1
kind: Workflow
metadata:
name: deploy-demo
namespace: demo
steps: #顺序部署cluster1-beijing,cluster2-beijing,cluster1-hangzhou。
- type: deploy
name: deploy-cluster1-beijing
properties:
policies: ["cluster1-beijing"]
- type: deploy
name: deploy-cluster2-beijing
properties:
auto: false #部署cluster2-beijing前需要人工审核
policies: ["override-env-cluster2-beijing", "cluster2-beijing"] #在部署cluster2-beijing时做环境变量的差异化
- type: deploy
name: deploy-cluster1-hangzhou
properties:
policies: ["override-env-cluster1-hangzhou", "override-replic-cluster1-hangzhou", "override-configmap-cluster1-hangzhou", "cluster1-hangzhou"]
#在部署cluster2-beijing时做环境变量,副本数,configmap的差异化
---
apiVersion: core.oam.dev/v1beta1
kind: Application
metadata:
annotations:
app.oam.dev/publishVersion: version8
name: web-demo
namespace: demo
spec:
components:
- name: deployment #独立引用deployment,方便差异化配置
type: ref-objects
properties:
objects:
- apiVersion: apps/v1
kind: Deployment
name: web-demo
- name: configmap #独立引用configmap,方便差异化配置
type: ref-objects
properties:
objects:
- apiVersion: v1
kind: ConfigMap
name: web-demo
- name: same-resource #不做差异化配置
type: ref-objects
properties:
objects:
- apiVersion: v1
kind: Service
name: web-demo
- apiVersion: networking.k8s.io/v1
kind: Ingress
name: web-demo
workflow:
ref: deploy-demo
- 执行以下命令,在主控实例上部署分发规则 app.yaml。
kubectl apply -f app.yaml
- 查看应用的部署状态。
kubectl get app web-demo -n demo
预期输出,workflowSuspending 表示部署暂停
NAME COMPONENT TYPE PHASE HEALTHY STATUS AGE
web-demo deployment ref-objects workflowSuspending true 47h
- 查看应用在各个集群上的运行状态
kubectl amc get deployment web-demo -n demo -m all
预期输出:
Run on ManagedCluster managedcluster-cxxx (cluster1-hangzhou)
No resources found in demo namespace #第一次新部署应用,工作流还没有开始部署cluster1-hangzhou
Run on ManagedCluster managedcluster-cxxx (cluster2-beijing)
No resources found in demo namespace #第一次新部署应用,工作流还没有开始部署cluster2-beijiing,等待人工审核
Run on ManagedCluster managedcluster-cxxx (cluster1-beijing)
NAME READY UP-TO-DATE AVAILABLE AGE
web-demo 5/5 5 5 47h #Deployment在cluster1-beijing集群上运行正常
- 人工审核通过,部署集群 cluster2-beijing,cluster1-hangzhou。
kubectl amc workflow resume web-demo -n demo
Successfully resume workflow: web-demo
- 查看应用的部署状态。
kubectl get app web-demo -n demo
预期输出,running 表示应用运行正常
NAME COMPONENT TYPE PHASE HEALTHY STATUS AGE
web-demo deployment ref-objects running true 47h
- 查看应用在各个集群上的运行状态
kubectl amc get deployment web-demo -n demo -m all
预期输出:
Run on ManagedCluster managedcluster-cxxx (cluster1-hangzhou)
NAME READY UP-TO-DATE AVAILABLE AGE
web-demo 1/1 1 1 47h
Run on ManagedCluster managedcluster-cxxx (cluster2-beijing)
NAME READY UP-TO-DATE AVAILABLE AGE
web-demo 5/5 5 5 2d
Run on ManagedCluster managedcluster-cxxx (cluster1-beijing)
NAME READY UP-TO-DATE AVAILABLE AGE
web-demo 5/5 5 5 47h
- 查看应用在各个集群上的 Ingress 状态
kubectl amc get ingress -n demo -m all
预期结果,每个集群的 Ingress 运行正常,公网 IP 分配成功。
Run on ManagedCluster managedcluster-cxxx (cluster1-hangzhou)
NAME CLASS HOSTS ADDRESS PORTS AGE
web-demo nginx web-demo.example.com 47.xxx.xxx.xxx 80 47h
Run on ManagedCluster managedcluster-cxxx (cluster2-beijing)
NAME CLASS HOSTS ADDRESS PORTS AGE
web-demo nginx web-demo.example.com 123.xxx.xxx.xxx 80 2d
Run on ManagedCluster managedcluster-cxxx (cluster1-beijing)
NAME CLASS HOSTS ADDRESS PORTS AGE
web-demo nginx web-demo.example.com 182.xxx.xxx.xxx 80 2d
流量管理
通过配置全局流量管理,自动检测应用运行状态,并在异常发生时,自动切换流量到监控集群。
- 配置全局流量管理实例,web-demo.example.com 为示例应用的域名,请替换为实际应用的域名,并设置 DNS 解析到全局流量管理的 CNAME 接入域名。
- 在已创建的 GTM 示例中,创建 2 个地址池:
pool-beijing:包含 2 个北京集群的 Ingress IP 地址,负载均衡策略为返回全部地址,实现北京 2 个集群的负载均衡。Ingress IP 地址可通过在主控实例上运行 “kubectl amc get ingress -n demo -m all” 获取。
pool-hangzhou:包含 1 个杭州集群的 Ingress IP 地址。
- 在地址池中开启健康检查,检查失败的地址将从地址池中移除,不再接收流量。
- 配置访问策略,设置主地址池为北京地址池,备地址池为杭州地址池。正常流量都有北京集群应用处理,当所有北京集群应用不可用时,自动切换到杭州集群应用处理。
部署验证
- 正常情况,所有有流量都有北京的 2 个集群上的应用处理,每个集群各处理 50% 流量。
for i in {1..50}; do curl web-demo.example.com; sleep 3; done
This is env cluster1-beijing !
Config file is {
database-host: "beijing-db.pg.aliyun.com"
}
This is env cluster1-beijing !
Config file is {
database-host: "beijing-db.pg.aliyun.com"
}
This is env cluster2-beijing !
Config file is {
database-host: "beijing-db.pg.aliyun.com"
}
This is env cluster1-beijing !
Config file is {
database-host: "beijing-db.pg.aliyun.com"
}
This is env cluster2-beijing !
Config file is {
database-host: "beijing-db.pg.aliyun.com"
}
This is env cluster2-beijing !
Config file is {
database-host: "beijing-db.pg.aliyun.com"
}
- 当集群 cluster1-beijing 上的应用异常时,GTM 将所有的流量路由到 cluster2-bejing 集群处理。
for i in {1..50}; do curl web-demo.example.com; sleep 3; done
...
503 Service Temporarily Unavailable
503 Service Temporarily Unavailable
nginx
This is env cluster2-beijing !
Config file is {
database-host: "beijing-db.pg.aliyun.com"
}
This is env cluster2-beijing !
Config file is {
database-host: "beijing-db.pg.aliyun.com"
}
This is env cluster2-beijing !
Config file is {
database-host: "beijing-db.pg.aliyun.com"
}
This is env cluster2-beijing !
Config file is {
database-host: "beijing-db.pg.aliyun.com"
}
- 当集群 cluster1-beijing 和 cluster2-beijing 上的应用同时异常时,GTM 将流量路由到 cluster1-hangzhou 集群处理。
for i in {1..50}; do curl web-demo.example.com; sleep 3; done
503 Service Temporarily Unavailable
503 Service Temporarily Unavailable
nginx