服务拓扑

使用服务拓扑实现边缘流量闭环能力

服务拓扑（Service Topology）可以让一个服务根据集群的节点拓扑进行流量路由。 例如，一个服务可以指定流量被优先路由到和客户端 pod 相同的节点或者节点池上。

通过在原生的 Service 上添加 Annotation 实现流量的拓扑配置，相关参数如下所示：

annotation Keyannotation Value说明
openyurt.io/topologyKeyskubernetes.io/hostname流量被路由到相同的节点
openyurt.io/topologyKeysopenyurt.io/nodepool
或
kubernetes.io/zone
流量被路由到相同的节点池

下图为服务拓扑功能的一个例子。service-ud1 添加了注解 openyurt.io/topologyKeys: openyurt.io/nodepool , 当 pod6 访问 service-ud1 的时候，由于 pod6 位于 edge node2，也就是位于杭州节点池，因此其流量只会发往杭州节点池的 pod1 或 pod2上，而不会跨节点池，所以 pod3 和 pod4 收不到。从而实现了同一个节点池中的流量闭环。

service-topology

前提条件

  1. Kubernetes v1.18或以上版本，因为需要支持 EndpointSlice 资源。
  2. 集群中部署了 Yurt-app-manager。

使用方法演示

确保 Kubernetes 版本大于1.18。

  1. $ kubectl get node
  2. NAME                 STATUS   ROLES    AGE     VERSION
  3. kind-control-plane   Ready    master   6m21s   v1.18.19
  4. kind-worker          Ready    <none>   5m42s   v1.18.19
  5. kind-worker2         Ready    <none>   5m42s   v1.18.19

确保集群中部署了 Yurt-app-manager。

  1. $ kubectl get pod -n kube-system 
  2. NAME                                         READY   STATUS    RESTARTS   AGE
  3. coredns-66bff467f8-jxvnw                     1/1     Running   0          7m28s
  4. coredns-66bff467f8-lk8v5                     1/1     Running   0          7m28s
  5. etcd-kind-control-plane                      1/1     Running   0          7m39s
  6. kindnet-5dpxt                                1/1     Running   0          7m28s
  7. kindnet-ckz88                                1/1     Running   0          7m10s
  8. kindnet-sqxs7                                1/1     Running   0          7m10s
  9. kube-apiserver-kind-control-plane            1/1     Running   0          7m39s
  10. kube-controller-manager-kind-control-plane   1/1     Running   0          5m38s
  11. kube-proxy-ddgjt                             1/1     Running   0          7m28s
  12. kube-proxy-j25kr                             1/1     Running   0          7m10s
  13. kube-proxy-jt9cw                             1/1     Running   0          7m10s
  14. kube-scheduler-kind-control-plane            1/1     Running   0          7m39s
  15. yurt-app-manager-699ffdcb78-8m9sf            1/1     Running   0          37s
  16. yurt-app-manager-699ffdcb78-fdqmq            1/1     Running   0          37s
  17. yurt-controller-manager-6c95788bf-jrqts      1/1     Running   0          6m17s
  18. yurt-hub-kind-control-plane                  1/1     Running   0          3m36s
  19. yurt-hub-kind-worker                         1/1     Running   0          4m50s
  20. yurt-hub-kind-worker2                        1/1     Running   0          4m50s

配置 kube-proxy

开启 kube-proxy 的 EndpointSliceProxying [特性门控](特性门控 | Kubernetes)，并配置其连接 Yurthub。

  1. $ kubectl edit cm -n kube-system kube-proxy
  2. apiVersion: v1
  3. data:
  4.   config.conf: |-
  5.     apiVersion: kubeproxy.config.k8s.io/v1alpha1
  6.     bindAddress: 0.0.0.0
  7.     featureGates: # 1. enable EndpointSliceProxying feature gate.
  8.       EndpointSliceProxying: true
  9.     clientConnection:
  10.       acceptContentTypes: ""
  11.       burst: 0
  12.       contentType: ""
  13.       #kubeconfig: /var/lib/kube-proxy/kubeconfig.conf # 2. comment this line.
  14.       qps: 0
  15.     clusterCIDR: 10.244.0.0/16
  16.     configSyncPeriod: 0s

重启 kube-proxy。

  1. $ kubectl delete pod --selector k8s-app=kube-proxy -n kube-system
  2. pod "kube-proxy-cbsmj" deleted
  3. pod "kube-proxy-cqwcs" deleted
  4. pod "kube-proxy-m9dgk" deleted

创建节点池

  • 创建用于测试的节点池。
  1. $ cat << EOF | kubectl apply -f -
  2. apiVersion: apps.openyurt.io/v1alpha1
  3. kind: NodePool
  4. metadata:
  5.   name: beijing
  6. spec:
  7.   type: Cloud
  9. ---
  11. apiVersion: apps.openyurt.io/v1alpha1
  12. kind: NodePool
  13. metadata:
  14.   name: hangzhou
  15. spec:
  16.   type: Edge
  17.   annotations:
  18.     apps.openyurt.io/example: test-hangzhou
  19.   labels:
  20.     apps.openyurt.io/example: test-hangzhou
  22. ---
  24. apiVersion: apps.openyurt.io/v1alpha1
  25. kind: NodePool
  26. metadata:
  27.   name: shanghai
  28. spec:
  29.   type: Edge
  30.   annotations:
  31.     apps.openyurt.io/example: test-shanghai
  32.   labels:
  33.     apps.openyurt.io/example: test-shanghai
  34. EOF
  • 将主节点 kind-control-plane 加入到北京节点池，工作节点 kind-worker 加入到杭州节点池， kind-worker2 加入到上海节点池。
  1. $ kubectl label node kind-control-plane apps.openyurt.io/desired-nodepool=beijing
  2. node/kind-control-plane labeled
  4. $ kubectl label node kind-worker apps.openyurt.io/desired-nodepool=hangzhou
  5. node/kind-worker labeled
  7. $ kubectl label node kind-worker2 apps.openyurt.io/desired-nodepool=shanghai
  8. node/kind-worker2 labeled
  • 查看节点池信息。
  1. $ kubectl get np
  2. NAME       TYPE    READYNODES   NOTREADYNODES   AGE
  3. beijing    Cloud   1            0               63s
  4. hangzhou   Edge    1            0               63s
  5. shanghai   Edge    1            0               63s

创建 UnitedDeployment

  • 创建 united-deployment1 用于测试。为了便于测试，我们使用 serve_hostname 镜像，当访问 9376 端口时，容器会返回它自己的主机名。
  1. $ cat << EOF | kubectl apply -f -
  2. apiVersion: apps.openyurt.io/v1alpha1
  3. kind: UnitedDeployment
  4. metadata:
  5.   labels:
  6.     controller-tools.k8s.io: "1.0"
  7.   name: united-deployment1
  8. spec:
  9.   selector:
  10.     matchLabels:
  11.       app: united-deployment1
  12.   workloadTemplate:
  13.     deploymentTemplate:
  14.       metadata:
  15.         labels:
  16.           app: united-deployment1
  17.       spec:
  18.         template:
  19.           metadata:
  20.             labels:
  21.               app: united-deployment1
  22.           spec:
  23.             containers:
  24.               - name: hostname
  25.                 image: mirrorgooglecontainers/serve_hostname
  26.                 ports:
  27.                 - containerPort: 9376
  28.                   protocol: TCP
  29.   topology:
  30.     pools:
  31.     - name: hangzhou
  32.       nodeSelectorTerm:
  33.         matchExpressions:
  34.         - key: apps.openyurt.io/nodepool
  35.           operator: In
  36.           values:
  37.           - hangzhou
  38.       replicas: 2
  39.     - name: shanghai
  40.       nodeSelectorTerm:
  41.         matchExpressions:
  42.         - key: apps.openyurt.io/nodepool
  43.           operator: In
  44.           values:
  45.           - shanghai
  46.       replicas: 2
  47.   revisionHistoryLimit: 5
  48. EOF
  • 创建 united-deployment2 用于测试。这里我们使用nginx 镜像，用来访问由 united-deployment1 创建的 hostname pod。
  1. $ cat << EOF | kubectl apply -f -
  2. apiVersion: apps.openyurt.io/v1alpha1
  3. kind: UnitedDeployment
  4. metadata:
  5.   labels:
  6.     controller-tools.k8s.io: "1.0"
  7.   name: united-deployment2
  8. spec:
  9.   selector:
  10.     matchLabels:
  11.       app: united-deployment2
  12.   workloadTemplate:
  13.     deploymentTemplate:
  14.       metadata:
  15.         labels:
  16.           app: united-deployment2
  17.       spec:
  18.         template:
  19.           metadata:
  20.             labels:
  21.               app: united-deployment2
  22.           spec:
  23.             containers:
  24.               - name: nginx
  25.                 image: nginx:1.19.3
  26.                 ports:
  27.                 - containerPort: 80
  28.                   protocol: TCP
  29.   topology:
  30.     pools:
  31.     - name: hangzhou
  32.       nodeSelectorTerm:
  33.         matchExpressions:
  34.         - key: apps.openyurt.io/nodepool
  35.           operator: In
  36.           values:
  37.           - hangzhou
  38.       replicas: 2
  39.     - name: shanghai
  40.       nodeSelectorTerm:
  41.         matchExpressions:
  42.         - key: apps.openyurt.io/nodepool
  43.           operator: In
  44.           values:
  45.           - shanghai
  46.       replicas: 2
  47.   revisionHistoryLimit: 5
  48. EOF
  • 查看由上述 unitedDeployment 创建出来的 pod 信息。
  1. $ kubectl get pod -l "app in (united-deployment1,united-deployment2)" -o wide
  2. NAME                                                 READY   STATUS    RESTARTS   AGE   IP           NODE           NOMINATED NODE   READINESS GATES
  3. united-deployment1-hangzhou-fv6th-66ff6fd958-f2694   1/1     Running   0          18m   10.244.2.3   kind-worker    <none>           <none>
  4. united-deployment1-hangzhou-fv6th-66ff6fd958-twf95   1/1     Running   0          18m   10.244.2.2   kind-worker    <none>           <none>
  5. united-deployment1-shanghai-5p8zk-84bdd476b6-hr6xt   1/1     Running   0          18m   10.244.1.3   kind-worker2   <none>           <none>
  6. united-deployment1-shanghai-5p8zk-84bdd476b6-wjck2   1/1     Running   0          18m   10.244.1.2   kind-worker2   <none>           <none>
  7. united-deployment2-hangzhou-lpkzg-6d958b67b6-gf847   1/1     Running   0          15m   10.244.2.4   kind-worker    <none>           <none>
  8. united-deployment2-hangzhou-lpkzg-6d958b67b6-lbnwl   1/1     Running   0          15m   10.244.2.5   kind-worker    <none>           <none>
  9. united-deployment2-shanghai-tqgd4-57f7555494-9jvjb   1/1     Running   0          15m   10.244.1.5   kind-worker2   <none>           <none>
  10. united-deployment2-shanghai-tqgd4-57f7555494-rn8n8   1/1     Running   0          15m   10.244.1.4   kind-worker2   <none>           <none>

创建含有 openyurt.io/topologyKeys 注解的服务

  1. $ cat << EOF | kubectl apply -f -
  2. apiVersion: v1
  3. kind: Service
  4. metadata:
  5.   name: svc-ud1
  6.   annotations:
  7.     openyurt.io/topologyKeys: openyurt.io/nodepool
  8. spec:
  9.   selector:
  10.     app: united-deployment1
  11.   type: ClusterIP
  12.   ports:
  13.   - port: 80
  14.     targetPort: 9376
  15. EOF

创建不含 openyurt.io/topologyKeys 注解的服务

  1. $ cat << EOF | kubectl apply -f -
  2. apiVersion: v1
  3. kind: Service
  4. metadata:
  5.   name: svc-ud1-without-topology
  6. spec:
  7.   selector:
  8.     app: united-deployment1
  9.   type: ClusterIP
  10.   ports:
  11.   - port: 80
  12.     targetPort: 9376
  13. EOF

测试服务拓扑功能

通过使用上海节点池中的 pod 访问上述创建的两个服务来测试服务拓扑功能。当访问含有 openyurt.io/topologyKeys 注解的服务时，流量会被路由到位于上海节点池中的节点上。

为了进行比较，我们首先测试没有openyurt.io/topologyKeys注解的服务。结果如下，可以看到它的流量既可以被杭州节点池接收，也能被上海节点池接收，并不受节点池的限制。

  1. $ kubectl exec -it united-deployment2-shanghai-tqgd4-57f7555494-9jvjb bash
  2. root@united-deployment2-shanghai-tqgd4-57f7555494-9jvjb:/# curl svc-ud1-without-topology:80
  3. united-deployment1-hangzhou-fv6th-66ff6fd958-twf95
  4. root@united-deployment2-shanghai-tqgd4-57f7555494-9jvjb:/# curl svc-ud1-without-topology:80
  5. united-deployment1-shanghai-5p8zk-84bdd476b6-hr6xt
  6. root@united-deployment2-shanghai-tqgd4-57f7555494-9jvjb:/# curl svc-ud1-without-topology:80
  7. united-deployment1-hangzhou-fv6th-66ff6fd958-twf95
  8. root@united-deployment2-shanghai-tqgd4-57f7555494-9jvjb:/# curl svc-ud1-without-topology:80
  9. united-deployment1-hangzhou-fv6th-66ff6fd958-f2694

然后我们测试含有openyurt.io/topologyKeys注解的服务。结果如下，可以看到其流量只能路由到上海节点池中的节点。

  1. $ kubectl exec -it united-deployment2-shanghai-tqgd4-57f7555494-9jvjb bash
  2. root@united-deployment2-shanghai-tqgd4-57f7555494-9jvjb:/# curl svc-ud1:80
  3. united-deployment1-shanghai-5p8zk-84bdd476b6-wjck2
  4. root@united-deployment2-shanghai-tqgd4-57f7555494-9jvjb:/# curl svc-ud1:80
  5. united-deployment1-shanghai-5p8zk-84bdd476b6-hr6xt
  6. root@united-deployment2-shanghai-tqgd4-57f7555494-9jvjb:/# curl svc-ud1:80
  7. united-deployment1-shanghai-5p8zk-84bdd476b6-wjck2
  8. root@united-deployment2-shanghai-tqgd4-57f7555494-9jvjb:/# curl svc-ud1:80
  9. united-deployment1-shanghai-5p8zk-84bdd476b6-hr6xt