Merge pull request #27583 from zhiguo-lu/zh-trans-concepts-service-internal-traffic-policy

[zh] translate concepts/Service Internal Traffic Policy

Author: k8s-ci-robot

content/zh/docs/concepts/services-networking/service-traffic-policy.md

@@ -0,0 +1,128 @@
+---
+title: 服务内部流量策略
+content_type: concept
+weight: 45
+---
+<!-- 
+---
+reviewers:
+- maplain
+title: Service Internal Traffic Policy
+content_type: concept
+weight: 45
+---
+-->
+
+<!-- overview -->
+
+{{< feature-state for_k8s_version="v1.21" state="alpha" >}}
+
+<!-- 
+_Service Internal Traffic Policy_ enables internal traffic restrictions to only route
+internal traffic to endpoints within the node the traffic originated from. The
+"internal" traffic here refers to traffic originated from Pods in the current
+cluster. This can help to reduce costs and improve performance.
+-->
+_服务内部流量策略_ 开启了内部流量限制，只路由内部流量到和发起方处于相同节点的服务端点。
+这里的”内部“流量指当前集群中的 Pod 所发起的流量。
+这种机制有助于节省开销，提升效率。
+
+<!-- body -->
+
+<!-- 
+## Using Service Internal Traffic Policy
+-->
+## 使用服务内部流量策略 {#using-service-internal-traffic-policy}
+
+<!-- 
+Once you have enabled the `ServiceInternalTrafficPolicy`
+[feature gate](/docs/reference/command-line-tools-reference/feature-gates/),
+you can enable an internal-only traffic policy for a
+{{< glossary_tooltip text="Services" term_id="service" >}}, by setting its
+`.spec.internalTrafficPolicy` to `Local`.
+This tells kube-proxy to only use node local endpoints for cluster internal traffic.
+-->
+一旦你启用了 `ServiceInternalTrafficPolicy` 这个
+[特性门控](/zh/docs/reference/command-line-tools-reference/feature-gates/),
+你就可以通过将 {{< glossary_tooltip text="Services" term_id="service" >}} 的 
+`.spec.internalTrafficPolicy` 项设置为 `Local`，
+来为它指定一个内部专用的流量策略。
+此设置就相当于告诉 kube-proxy 对于集群内部流量只能使用本地的服务端口。
+
+<!-- 
+For pods on nodes with no endpoints for a given Service, the Service
+behaves as if it has zero endpoints (for Pods on this node) even if the service
+does have endpoints on other nodes.
+-->
+{{< note >}}
+如果某节点上的 Pod 均不提供指定 Service 的服务端点，
+即使该 Service 在其他节点上有可用的服务端点，
+Service 的行为看起来也像是它只有 0 个服务端点（只针对此节点上的 Pod）。
+{{< /note >}}
+
+<!-- 
+The following example shows what a Service looks like when you set
+`.spec.internalTrafficPolicy` to `Local`:
+-->
+以下示例展示了把 Service 的 `.spec.internalTrafficPolicy` 项设为 `Local` 时，
+Service 的样子：
+
+
+```yaml
+apiVersion: v1
+kind: Service
+metadata:
+  name: my-service
+spec:
+  selector:
+    app: MyApp
+  ports:
+    - protocol: TCP
+      port: 80
+      targetPort: 9376
+  internalTrafficPolicy: Local
+```
+
+<!-- 
+## How it works
+-->
+## 工作原理 {#how-it-works}
+
+<!-- 
+The kube-proxy filters the endpoints it routes to based on the
+`spec.internalTrafficPolicy` setting. When it's set to `Local`, only node local
+endpoints are considered. When it's `Cluster` or missing, all endpoints are
+considered.
+When the [feature gate](/docs/reference/command-line-tools-reference/feature-gates/)
+`ServiceInternalTrafficPolicy` is enabled, `spec.internalTrafficPolicy` defaults to "Cluster".
+-->
+kube-proxy 基于 `spec.internalTrafficPolicy` 的设置来过滤路由的目标服务端点。
+当它的值设为 `Local` 时，只选择节点本地的服务端点。
+当它的值设为 `Cluster` 或缺省时，则选择所有的服务端点。
+启用[特性门控](/zh/docs/reference/command-line-tools-reference/feature-gates/)
+`ServiceInternalTrafficPolicy` 后，
+`spec.internalTrafficPolicy` 的值默认设为 `Cluster`。
+
+<!-- 
+## Constraints
+-->
+## 限制 {#constraints}
+
+<!-- 
+* Service Internal Traffic Policy is not used when `externalTrafficPolicy` is set
+  to `Local` on a Service. It is possible to use both features in the same cluster
+  on different Services, just not on the same Service.
+-->
+* 在一个Service上，当 `externalTrafficPolicy` 已设置为 `Local`时，服务内部流量策略无法使用。
+  换句话说，在一个集群的不同 Service 上可以同时使用这两个特性，但在一个 Service 上不行。
+
+## {{% heading "whatsnext" %}}
+
+<!-- 
+* Read about [enabling Topology Aware Hints](/docs/tasks/administer-cluster/enabling-topology-aware-hints)
+* Read about [Service External Traffic Policy](/docs/tasks/access-application-cluster/create-external-load-balancer/#preserving-the-client-source-ip)
+* Read [Connecting Applications with Services](/docs/concepts/services-networking/connect-applications-service/)
+-->
+* 请阅读[启用拓扑感知提示](/zh/docs/tasks/administer-cluster/enabling-topology-aware-hints)
+* 请阅读[Service 的外部流量策略](/zh/docs/tasks/access-application-cluster/create-external-load-balancer/#preserving-the-client-source-ip)
+* 请阅读[用 Service 连接应用](/zh/docs/concepts/services-networking/connect-applications-service/)