第五节 Istio 灰度发布与技术实现
大纲
- 典型发布类型对比
- Istio流量治理技术解析
- 智能灰度发布介绍
- 灰度发布功能展示Demo
1、发布类型
- 蓝绿发布
- 灰度发布(金丝雀发布)
- A/B Test
1-1 蓝绿发布
- Green * 3 => ELB
- Blue * 3 CREATED
- Blue * 3 => ELB
- Green * 3 Deleted
1-2 金丝雀发布
- Green * 3 * 100% => ELB
- Blue * 3 CREATED
- Green * 3 * 90% + Blue * 3 * 10% => ELB
- Blue * 3 * 100% => ELB
1-3 A/B Test
-
V1 * 3 + V2 * 3 => ELB
-
配置策略
- 监控指标
- 分析数据
- 作出决策
- 执行决策
A/B Test主要对特定用户采样后，对收集到的反馈数据做相关对比，然后根据比对结果作出决策。
用来测试应用功能表现的方法，侧重应用的可用性，受欢迎程度等。
2、Istio 流量管理
2-1 配置规则 👍
VirtualService在 Istio 服务网格中定义路由规则，控制路由如何路由到服务上。DestinationRule是VirtualService路由生效后，配置应用与请求的策略集。ServiceEntry是通常用于在 Istio 服务网格之外启用对服务的请求。Gateway为HTTP/TCP流量配置负载均衡器，最常见的是在网格的边缘的操作，以启用应用程序的入口流量。
2-2 DestinationRule
apiVersion: networking.istio.io/v1alpha3
kind: DestinationRule
metadata:
name: bookinfo-ratings
spec:
host: ratings.prod.svc.cluster.local
trafficPolicy:
loadBalancer:
simple: RANDOM
subsets:
- name: v3
labels:
version: v3
trafficPolicy:
loadBalancer:
simple: ROUND_ROBIN
DestinationRule 所定义的策略，决定了经过路由处理之后的流量的访问策略。
- host —— 目标服务的名称
- trafficPolicy —— 流量策略(负载均衡配置、连接池配置和熔断配置)。
- subsets —— 一个或多个服务版本
2-3 Virtualservice
apiVersion: networking.istio.io/v1alpha3
kind: VirtualService
metadata:
name: myapp-route
spec:
gateways:
- mesh
hosts:
- myapp
http:
- match:
- port: 3711
route:
- destination:
host: myapp
port:
number: 8080
subset: v1
tcp:
- match:
- port: 3721
route:
- destination:
host: myapp
port:
number: 8009
VirtualService 定义了一系列针对指定服务的流量路由规则。
hosts—— 流量的目标主机gateways—— Gateway名称列表http——HTTP流量规则(HTTPRoute)的列表tcp——tcp流量规则(TCPRoute)的列表tls——tls和https(TLSRoute)流量规则的列表
HTTPRoute
HttpMatchRequest(uri,headers,port,method......)
DestinationWeight(destination，weight)
Redirect
Rewrite
Timeout
Retries
......
TCPRoute
L4MatchAttributes(destinationSubnets,port......)
DestinationWeight(destination，weight)
2-4 基于权重的路由
apiVersion: ...
kind: VirtualService
metadata:
name: vs-svcb
spec:
hosts:
- svcb
http:
route:
- destination:
name: v1
weight: 20
- destination:
name: v2
weight: 80
2-5 基于请求内容的路由
apiVersion: ...
kind: VirtualService
metadata:
name: ratings-route
spec:
hosts:
- svcb
http:
- match:
- headers: cookie:
exact: “group=dev”
route:
- destination:
name: v1
- route:
- destination:
name: v2
2-6 复杂灰度场景下的VirtualService
apiVersion: networking.istio.io/v1alpha3
kind: VirtualService
metadata:
name: helloworld
spec:
hosts:
- helloworld
http:
- match:
- headers:
cookie:
regex: "^(.*?;)?(email=[^;]*@some-company-name.com)(;.*)?$"
route:
- destination:
host: helloworld
subset: v1
weight: 50
- destination:
host: helloworld
subset: v2
weight: 50
- route:
- destination:
host: helloworld
subset: v1
2-7 灰度版本存在形式
kind: Deployment
metadata:
name: rating-v1
spec:
replicas: 2
template:
metadata:
labels:
app: rating
version: v1
spec:
containers:
- image: rating-v1
...
kind: Deployment
metadata:
name: rating-v2
spec:
replicas: 3
template:
metadata:
labels:
app: rating
version: v2
spec:
containers:
- image: rating-v2
...
2-8 灰度发布流程
3、智能灰度发布
目标:细粒度控制的自动化的持续交付
3-1 特点:
- 用户细分
- 流量管理
- 关键指标可观测
- 发布流程自动化
3-2 智能灰度发布
3-3 自适应灰度发布参数
- 负载健康状态
- 请求成功率
- 平均请求时延
- 流量权重步长
- 回滚门限值
3-4 监控指标
RED
- (Request) Rate - the number of requests, per second, your services are serving.
- (Request) Errors - the number of failed requests per second.
- (Request) Duration - The amount of time each request takes expressed as a time interval
USE(utilization，saturation，errors)
- CPUs: sockets, cores, hardware threads (virtual CPUs)
- Memory: capacity
- Network interfaces
- Storage devices: I/O, capacity
- Controllers: storage, network cards
- Interconnects: CPUs, memory, I/O
3-5 flagger
Flagger is a Kubernetes operator that automates the promotion of canary deployments using Istio routing for traffic shifting and Prometheus metrics for canary analysis.
