金丝雀发布
先在小范围公布，然后大范围。
一般情况：先发布v1，然后发布v2，然后扩大v2，缩小v1，直到v1版本全部被替换。
部署策略对比：蓝绿部署、金丝雀发布及其他_DevOps_Jason Skowronski_InfoQ精选文章
介绍
金丝雀部署(canary deployment)也被称为灰度发布。
早期，工人下矿井之前会放入一只金丝雀检测井下是否存在有毒气体。
采用金丝雀部署，你可以在生产环境的基础设施中小范围的部署新的应用代码。
一旦应用签署发布，只有少数用户被路由到它，最大限度的降低影响。
如果没有错误发生，则将新版本逐渐推广到整个基础设施。
如果没有错误发生，则将新版本逐渐推广到整个基础设施。
部署过程
发布第一个版本v1
发布v1版本的应用，镜像使用nginx:1.22,数量为 3。
- 创建Namespace
- 创建Deployment
- 创建外部访问的Service
apiVersion: v1 kind: Namespace metadata: name: dev --- apiVersion: apps/v1 kind: Deployment metadata: name: nginx-deployment-v1 namespace: dev labels: app: nginx-deployment-v1 spec: replicas: 3 selector: matchLabels: # 跟template.metadata.labels一致 app: nginx template: metadata: labels: app: nginx spec: containers: - name: nginx image: nginx:1.22 ports: - containerPort: 80 --- apiVersion: v1 kind: Service metadata: name: canary-demo namespace: dev spec: type: NodePort selector: # 跟Deployment中的selector一致 app: nginx ports: # By default and for convenience, the `targetPort` is set to the same value as the `port` field. - port: 80 targetPort: 80 # Optional field # By default and for convenience, the Kubernetes control plane will allocate a port from a range (default: 30000-32767) nodePort: 30008
发布第一个版本v1
[root@k8s home]# vim deploy-v1.yaml [root@k8s home]# kubectl apply -f deploy-v1.yaml namespace/dev created deployment.apps/nginx-deployment-v1 created service/canary-demo created
查看命名空间的的信息，并访问服务ip，查看服务详情
[root@k8s home]# kubectl get all -n=dev NAME READY STATUS RESTARTS AGE pod/nginx-deployment-v1-645549fcf7-r872x 1/1 Running 0 14s pod/nginx-deployment-v1-645549fcf7-wth5r 1/1 Running 0 14s pod/nginx-deployment-v1-645549fcf7-rkm5m 1/1 Running 0 14s NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE service/canary-demo NodePort 10.43.139.107 <none> 80:30008/TCP 14s NAME READY UP-TO-DATE AVAILABLE AGE deployment.apps/nginx-deployment-v1 3/3 3 3 14s NAME DESIRED CURRENT READY AGE replicaset.apps/nginx-deployment-v1-645549fcf7 3 3 3 14s [root@k8s home]# curl 10.43.139.107 <!DOCTYPE html> <html> <head> <title>Welcome to nginx!</title> <style> html { color-scheme: light dark; } body { width: 35em; margin: 0 auto; font-family: Tahoma, Verdana, Arial, sans-serif; } </style> </head> <body> <h1>Welcome to nginx!</h1> <p>If you see this page, the nginx web server is successfully installed and working. Further configuration is required.</p> <p>For online documentation and support please refer to <a href="http://nginx.org/">nginx.org</a>.<br/> Commercial support is available at <a href="http://nginx.com/">nginx.com</a>.</p> <p><em>Thank you for using nginx.</em></p> </body> </html> [root@k8s home]# kubectl describe svc canary-demo -n=dev Name: canary-demo Namespace: dev Labels: <none> Annotations: <none> Selector: app=nginx Type: NodePort IP Family Policy: SingleStack IP Families: IPv4 IP: 10.43.139.107 IPs: 10.43.139.107 Port: <unset> 80/TCP TargetPort: 80/TCP NodePort: <unset> 30008/TCP Endpoints: 10.42.0.49:80,10.42.1.37:80,10.42.2.32:80 Session Affinity: None External Traffic Policy: Cluster Events: <none>
发布第二个版本Canary
发布新版本的应用，镜像使用docker/getting-started，数量为 1。
apiVersion: apps/v1 kind: Deployment metadata: name: nginx-deployment-canary namespace: dev labels: app: nginx-deployment-canary spec: replicas: 1 selector: matchLabels: # 跟template.metadata.labels一致 app: nginx template: metadata: labels: app: nginx track: canary spec: containers: - name: new-nginx image: docker/getting-started ports: - containerPort: 80
发布第二个版本
[root@k8s home]# vim deploy-canary.yaml [root@k8s home]# kubectl apply -f deploy-canary.yaml deployment.apps/nginx-deployment-canary created
查看命名空间对象，发现创建了
一个新的部署---deployment.apps/nginx-deployment-canary
对应的副本集---replicaset.apps/nginx-deployment-canary-74577469b5
对应运行的pod---pod/nginx-deployment-canary-74577469b5-gnkfw
[root@k8s home]# kubectl get all -n=dev NAME READY STATUS RESTARTS AGE pod/nginx-deployment-v1-645549fcf7-r872x 1/1 Running 0 8m59s pod/nginx-deployment-v1-645549fcf7-wth5r 1/1 Running 0 8m59s pod/nginx-deployment-v1-645549fcf7-rkm5m 1/1 Running 0 8m59s pod/nginx-deployment-canary-74577469b5-gnkfw 1/1 Running 0 68s NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE service/canary-demo NodePort 10.43.139.107 <none> 80:30008/TCP 8m59s NAME READY UP-TO-DATE AVAILABLE AGE deployment.apps/nginx-deployment-v1 3/3 3 3 8m59s deployment.apps/nginx-deployment-canary 1/1 1 1 68s NAME DESIRED CURRENT READY AGE replicaset.apps/nginx-deployment-v1-645549fcf7 3 3 3 8m59s replicaset.apps/nginx-deployment-canary-74577469b5 1 1 1 68s
查看服务，发现出现了 + 1 more...表示有个新的pod加入到服务中
[root@k8s home]# kubectl describe svc -n=dev Name: canary-demo Namespace: dev Labels: <none> Annotations: <none> Selector: app=nginx Type: NodePort IP Family Policy: SingleStack IP Families: IPv4 IP: 10.43.139.107 IPs: 10.43.139.107 Port: <unset> 80/TCP TargetPort: 80/TCP NodePort: <unset> 30008/TCP Endpoints: 10.42.0.49:80,10.42.1.37:80,10.42.2.32:80 + 1 more... Session Affinity: None External Traffic Policy: Cluster Events: <none>
我们多次访问该服务ip，会出现新的页面
[root@k8s home]# curl 10.43.139.107 <!doctype html><html lang=en class=no-js> <head><meta charset=utf-8><meta name=viewport content="width=device-width,initial-scale=1"><meta http-equiv=x-ua-compatible content="ie=edge"><meta name=description content="Getting Started with Docker"><script>var anchor=window.location.hash.substr(1);location.href="/tutorial/"+(anchor?"#"+anchor:"")</script><meta http-equiv=refresh content="0; url=/tutorial/"><meta name=robots content=noindex><link href=/tutorial/ rel=canonical><meta name=author content=Docker><meta name=lang:clipboard.copy content="Copy to clipboard"><meta name=lang:clipboard.copied content="Copied to clipboard"><meta name=lang:search.language content=en><meta name=lang:search.pipeline.stopwords content=True><meta name=lang:search.pipeline.trimmer content=True><meta name=lang:search.result.none content="No matching documents"><meta name=lang:search.result.one content="1 matching document"><meta name=lang:search.result.other content="# 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稳定后调整比例
当稳定后可以将第二个版本的pod从1变为3，扩大试用范围，将部署的v2版本数量调整为3，v1和v2的数量都是3个。
[root@k8s home]# kubectl scale deploy nginx-deployment-canary --replicas=3 -n=dev deployment.apps/nginx-deployment-canary scaled
再次查看发现新版本pod变为3
[root@k8s home]# kubectl get all -n=dev NAME READY STATUS RESTARTS AGE pod/nginx-deployment-v1-645549fcf7-r872x 1/1 Running 0 15m pod/nginx-deployment-v1-645549fcf7-wth5r 1/1 Running 0 15m pod/nginx-deployment-v1-645549fcf7-rkm5m 1/1 Running 0 15m pod/nginx-deployment-canary-74577469b5-gnkfw 1/1 Running 0 7m11s pod/nginx-deployment-canary-74577469b5-z2fhp 1/1 Running 0 23s pod/nginx-deployment-canary-74577469b5-k5hxd 1/1 Running 0 23s NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE service/canary-demo NodePort 10.43.139.107 <none> 80:30008/TCP 15m NAME READY UP-TO-DATE AVAILABLE AGE deployment.apps/nginx-deployment-v1 3/3 3 3 15m deployment.apps/nginx-deployment-canary 3/3 3 3 7m11s NAME DESIRED CURRENT READY AGE replicaset.apps/nginx-deployment-v1-645549fcf7 3 3 3 15m replicaset.apps/nginx-deployment-canary-74577469b5 3 3 3 7m11s
下线旧版本
最后下线所有v1版本，所有服务升级为v2版本。
下线v1--replicas=0
[root@k8s home]# kubectl scale deploy nginx-deployment-v1 --replicas=0 -n=dev deployment.apps/nginx-deployment-v1 scaled
查看pod，发现v1版本下线了，此时都行线上都是新版本
[root@k8s home]# kubectl get all -n=dev NAME READY STATUS RESTARTS AGE pod/nginx-deployment-canary-74577469b5-gnkfw 1/1 Running 0 28m pod/nginx-deployment-canary-74577469b5-z2fhp 1/1 Running 0 21m pod/nginx-deployment-canary-74577469b5-k5hxd 1/1 Running 0 21m NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE service/canary-demo NodePort 10.43.139.107 <none> 80:30008/TCP 36m NAME READY UP-TO-DATE AVAILABLE AGE deployment.apps/nginx-deployment-canary 3/3 3 3 28m deployment.apps/nginx-deployment-v1 0/0 0 0 36m NAME DESIRED CURRENT READY AGE replicaset.apps/nginx-deployment-canary-74577469b5 3 3 3 28m replicaset.apps/nginx-deployment-v1-645549fcf7 0 0 0 36m
清空环境
kubectl delete all --all -n=dev
局限性
按照 Kubernetes 默认支持的这种方式进行金丝雀发布，有一定的局限性：
- 不能根据用户注册时间、地区等请求中的内容属性进行流量分配
- 同一个用户如果多次调用该 Service，有可能第一次请求到了旧版本的 Pod，第二次请求到了新版本的 Pod
在 Kubernetes 中不能解决上述局限性的原因是：Kubernetes Service 只在 TCP 层面解决负载均衡的问题，并不对请求响应的消息内容做任何解析和识别。如果想要更完善地实现金丝雀发布，可以考虑Istio灰度发布。
