本指南演示了如何为 OSM 托管服务网格的外部目标配置熔断。

先决条件

• Kubernetes 集群运行版本 v1.22.9 或者更高。
• 已安装 OSM。
• 使用 kubectl 与 API server 交互。
• 已安装 osm 命令行工具，用于管理服务网格。
• OSM 版本不低于 v1.1.0

演示

下面的演示展示了一个负载测试客户端 fortio 将流量发送到服务网格的外部 service httpbin 。发送到网格服务外的流量被认为是 出口 流量, 其会被 出口流量策略 进行授权。我们将看到为外部 httpbin service 配置的流量熔断器被触发后，是如何影响 fortio 客户端。

1. 部署 httpbin service 到 httpbin 命名空间。httpbin service 运行在 14001 端口，且没有纳入网格管理，因此可以看成是网格外部的服务。

   # Create the httpbin namespace
   kubectl create namespace httpbin
      
   # Deploy httpbin service in the httpbin namespace
   kubectl apply -f https://raw.githubusercontent.com/openservicemesh/osm-docs/release-v1.2/manifests/samples/httpbin/httpbin.yaml -n httpbin
   

   确认 httpbin service 和 pod 启动并运行。

   $ kubectl get svc -n httpbin
   NAME      TYPE        CLUSTER-IP     EXTERNAL-IP   PORT(S)     AGE
   httpbin   ClusterIP   10.96.198.23   <none>        14001/TCP   20s
   

   $ kubectl get pods -n httpbin
   NAME                     READY   STATUS    RESTARTS   AGE
   httpbin-5b8b94b9-lt2vs   1/1     Running   0          20s
   

2. 将 fortio 负载测试客户端部署到 client 命名空间，并纳入服务网格。

   # Create the client namespace
   kubectl create namespace client
      
   # Add the namespace to the mesh
   osm namespace add client
      
   # Deploy fortio client in the client namespace
   kubectl apply -f https://raw.githubusercontent.com/openservicemesh/osm-docs/release-v1.2/manifests/samples/fortio/fortio.yaml -n client
   

   确认 fortio 客户端 pod 启动并运行

   $ kubectl get pods -n client
   NAME                      READY   STATUS    RESTARTS   AGE
   fortio-6477f8495f-bj4s9   2/2     Running   0          19s
   

3. 配置 Egress 策略允许 client 命名空间下的 fortio 客户端可以与外部的 httpbin service 进行通信。HTTP 请求将被发送到域名 httpbin.httpbin.svc.cluster.local 的 14001 端口。

   kubectl apply -f - <<EOF
   kind: Egress
   apiVersion: policy.openservicemesh.io/v1alpha1
   metadata:
     name: httpbin-external
     namespace: client
   spec:
     sources:
     - kind: ServiceAccount
       name: default
       namespace: client
     hosts:
     - httpbin.httpbin.svc.cluster.local
     ports:
     - number: 14001
       protocol: http
   EOF
   

4. 确认 fortio 客户端可以成功发送 HTTP 请求到外部 service httpbin.httpbin.svc.cluster.local 的 14001 端口。使用 5 个并发（-c 5）发送 50 个请求（-n 50）到外部服务。

   $ export fortio_pod="$(kubectl get pod -n client -l app=fortio -o jsonpath='{.items[0].metadata.name}')"
      
   $ kubectl exec "$fortio_pod" -c fortio -n client -- /usr/bin/fortio load -c 5 -qps 0 -n 50 -loglevel Warning http://httpbin.httpbin.svc.cluster.local:14001/get
   19:56:34 I logger.go:127> Log level is now 3 Warning (was 2 Info)
   Fortio 1.17.1 running at 0 queries per second, 8->8 procs, for 50 calls: http://httpbin.httpbin.svc.cluster.local:14001/get
   Starting at max qps with 5 thread(s) [gomax 8] for exactly 50 calls (10 per thread + 0)
   Ended after 36.3659ms : 50 calls. qps=1374.9
   Aggregated Function Time : count 50 avg 0.003374618 +/- 0.0007546 min 0.0013124 max 0.0066215 sum 0.1687309
   # range, mid point, percentile, count
   >= 0.0013124 <= 0.002 , 0.0016562 , 4.00, 2
   > 0.002 <= 0.003 , 0.0025 , 10.00, 3
   > 0.003 <= 0.004 , 0.0035 , 86.00, 38
   > 0.004 <= 0.005 , 0.0045 , 98.00, 6
   > 0.006 <= 0.0066215 , 0.00631075 , 100.00, 1
   # target 50% 0.00352632
   # target 75% 0.00385526
   # target 90% 0.00433333
   # target 99% 0.00631075
   # target 99.9% 0.00659043
   Sockets used: 5 (for perfect keepalive, would be 5)
   Jitter: false
   Code 200 : 50 (100.0 %)
   Response Header Sizes : count 50 avg 230 +/- 0 min 230 max 230 sum 11500
   Response Body/Total Sizes : count 50 avg 460 +/- 0 min 460 max 460 sum 23000
   All done 50 calls (plus 0 warmup) 3.375 ms avg, 1374.9 qps
   

   如上所示，全部请求成功。

   Code 200 : 50 (100.0 %)
   

5. 使用 UpstreamTrafficSetting 资源为请求到外部域名 httpbin.httpbin.svc.cluster.local 的流量应用配置熔断器，并将最大并发连接数和请求数限制为1。为外部（出口）流量应用 UpstreamTrafficSetting 配置时，UpstreamTrafficSetting 资源还必须在 Egress 配置中指定为匹配项，并且与匹配的 Egress 资源属于同一命名空间。这是为外部流量执行熔断限制时所必需的。因此，我们也要在之前应用的 Egress 配置中更新添加一个 matches 字段。

   kubectl apply -f - <<EOF
   apiVersion: policy.openservicemesh.io/v1alpha1
   kind: UpstreamTrafficSetting
   metadata:
     name: httpbin-external
     namespace: client
   spec:
     host: httpbin.httpbin.svc.cluster.local
     connectionSettings:
       tcp:
         maxConnections: 1
       http:
         maxPendingRequests: 1
         maxRequestsPerConnection: 1
   ---
   kind: Egress
   apiVersion: policy.openservicemesh.io/v1alpha1
   metadata:
     name: httpbin-external
     namespace: client
   spec:
     sources:
     - kind: ServiceAccount
       name: default
       namespace: client
     hosts:
     - httpbin.httpbin.svc.cluster.local
     ports:
     - number: 14001
       protocol: http
     matches:
     - apiGroup: policy.openservicemesh.io/v1alpha1
       kind: UpstreamTrafficSetting
       name: httpbin-external
   EOF
   

6. 确认由于上面配置的连接和请求级别熔断限制，fortio客户端无法发出与以前相同数量的成功请求。

   $ kubectl exec "$fortio_pod" -c fortio -n client -- /usr/bin/fortio load -c 5 -qps 0 -n 50 -loglevel Warning http://httpbin.httpbin.svc.cluster.local:14001/get
   19:58:48 I logger.go:127> Log level is now 3 Warning (was 2 Info)
   Fortio 1.17.1 running at 0 queries per second, 8->8 procs, for 50 calls: http://httpbin.httpbin.svc.cluster.local:14001/get
   Starting at max qps with 5 thread(s) [gomax 8] for exactly 50 calls (10 per thread + 0)
   19:58:48 W http_client.go:806> [0] Non ok http code 503 (HTTP/1.1 503)
   19:58:48 W http_client.go:806> [2] Non ok http code 503 (HTTP/1.1 503)
   19:58:48 W http_client.go:806> [2] Non ok http code 503 (HTTP/1.1 503)
   19:58:48 W http_client.go:806> [2] Non ok http code 503 (HTTP/1.1 503)
   19:58:48 W http_client.go:806> [2] Non ok http code 503 (HTTP/1.1 503)
   19:58:48 W http_client.go:806> [2] Non ok http code 503 (HTTP/1.1 503)
   19:58:48 W http_client.go:806> [1] Non ok http code 503 (HTTP/1.1 503)
   19:58:48 W http_client.go:806> [2] Non ok http code 503 (HTTP/1.1 503)
   19:58:48 W http_client.go:806> [2] Non ok http code 503 (HTTP/1.1 503)
   19:58:48 W http_client.go:806> [1] Non ok http code 503 (HTTP/1.1 503)
   19:58:48 W http_client.go:806> [4] Non ok http code 503 (HTTP/1.1 503)
   19:58:48 W http_client.go:806> [3] Non ok http code 503 (HTTP/1.1 503)
   19:58:48 W http_client.go:806> [3] Non ok http code 503 (HTTP/1.1 503)
   19:58:48 W http_client.go:806> [2] Non ok http code 503 (HTTP/1.1 503)
   19:58:48 W http_client.go:806> [3] Non ok http code 503 (HTTP/1.1 503)
   19:58:48 W http_client.go:806> [2] Non ok http code 503 (HTTP/1.1 503)
   19:58:48 W http_client.go:806> [3] Non ok http code 503 (HTTP/1.1 503)
   19:58:48 W http_client.go:806> [1] Non ok http code 503 (HTTP/1.1 503)
   19:58:48 W http_client.go:806> [3] Non ok http code 503 (HTTP/1.1 503)
   19:58:48 W http_client.go:806> [1] Non ok http code 503 (HTTP/1.1 503)
   19:58:48 W http_client.go:806> [4] Non ok http code 503 (HTTP/1.1 503)
   Ended after 33.1549ms : 50 calls. qps=1508.1
   Aggregated Function Time : count 50 avg 0.002467842 +/- 0.001827 min 0.0003724 max 0.0067697 sum 0.1233921
   # range, mid point, percentile, count
   >= 0.0003724 <= 0.001 , 0.0006862 , 34.00, 17
   > 0.001 <= 0.002 , 0.0015 , 50.00, 8
   > 0.002 <= 0.003 , 0.0025 , 60.00, 5
   > 0.003 <= 0.004 , 0.0035 , 84.00, 12
   > 0.004 <= 0.005 , 0.0045 , 88.00, 2
   > 0.005 <= 0.006 , 0.0055 , 92.00, 2
   > 0.006 <= 0.0067697 , 0.00638485 , 100.00, 4
   # target 50% 0.002
   # target 75% 0.003625
   # target 90% 0.0055
   # target 99% 0.00667349
   # target 99.9% 0.00676008
   Sockets used: 25 (for perfect keepalive, would be 5)
   Jitter: false
   Code 200 : 29 (58.0 %)
   Code 503 : 21 (42.0 %)
   Response Header Sizes : count 50 avg 133.4 +/- 113.5 min 0 max 230 sum 6670
   Response Body/Total Sizes : count 50 avg 368.02 +/- 108.1 min 241 max 460 sum 18401
   All done 50 calls (plus 0 warmup) 2.468 ms avg, 1508.1 qps
   

   如上所示，只有 58% 的请求成功，其余的请求在熔断器打开时失败

   Code 200 : 29 (58.0 %)
   Code 503 : 21 (42.0 %)
   

7. 检查 Envoy sidecar 统计信息以查看与触发断路器的请求有关的统计信息。

   $ osm proxy get stats $fortio_pod -n client | grep 'httpbin.*pending'
   cluster.httpbin_httpbin_svc_cluster_local_14001.circuit_breakers.default.remaining_pending: 1
   cluster.httpbin_httpbin_svc_cluster_local_14001.circuit_breakers.default.rq_pending_open: 0
   cluster.httpbin_httpbin_svc_cluster_local_14001.circuit_breakers.high.rq_pending_open: 0
   cluster.httpbin_httpbin_svc_cluster_local_14001.upstream_rq_pending_active: 0
   cluster.httpbin_httpbin_svc_cluster_local_14001.upstream_rq_pending_failure_eject: 0
   cluster.httpbin_httpbin_svc_cluster_local_14001.upstream_rq_pending_overflow: 21
   cluster.httpbin_httpbin_svc_cluster_local_14001.upstream_rq_pending_total: 29
   

   cluster.httpbin_httpbin_svc_cluster_local_14001.upstream_rq_pending_overflow: 21 表示有 21 个请求触发了熔断器，这与上一步中看到的失败请求数相匹配：Code 200 : 29 (58.0 %)。

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