envoy-02-lbsusets-原理及示例

 

 Envoy还支持在一个集群中基于子集实现更细粒度的流量分发

  首先，在集群的上游主机上添加元数据(键值标签)，并使用子集选择器(分类元数据)将上游主机划分为子集；

  而后，在路由配置中指定负载均衡器可以选择的且必须具有匹配的元数据的上游主机，从而实现向特定子集的路由；

  各子集内的主机间的负载均衡采用集群定义的策略(lb_policy)；

配置了子集，但路由并未指定元数据或不存在与指定元数据匹配的子集时，则子集均衡均衡

器为其应用“回退策略”

  NO_FALLBACK：请求失败，类似集群中不存在任何主机；此为默认策略；

  ANY_ENDPOINT：在所有主机间进行调度，不再考虑主机元数据；

  DEFAULT_SUBSET：调度至默认的子集，该子集需要事先定义；

 

子集必须预定义方可由子集负载均衡器在调度时使用

  定义主机元数据：键值数据

  主机的子集元数据必须要定义在“envoy.lb”过滤器下；

  仅当使用ClusterLoadAssignments定义主机时才支持主机元数据

通过EDS发现的端点

root@user:/opt/servicemesh_in_practise/Cluster-Manager/lb-subsets# cat front-envoy.yaml 

admin:
  access_log_path: "/dev/null"
  address:
    socket_address: { address: 0.0.0.0, port_value: 9901 }

static_resources:
  listeners:
  - address:
      socket_address: { address: 0.0.0.0, port_value: 80 }
    name: listener_http
    filter_chains:
    - filters:
      - name: envoy.filters.network.http_connection_manager
        typed_config:
          "@type": type.googleapis.com/envoy.extensions.filters.network.http_connection_manager.v3.HttpConnectionManager
          codec_type: auto
          stat_prefix: ingress_http
          route_config:
            name: local_route
            virtual_hosts:
            - name: backend
              domains:
              - "*"
              routes:
              - match:
                  prefix: "/"
                  headers:
                  - name: x-custom-version
                    exact_match: pre-release
                route:
                  cluster: webcluster1
                  metadata_match:
                    filter_metadata:
                      envoy.lb:
                        version: "1.2-pre"
                        stage: "dev"
              - match:
                  prefix: "/"
                  headers:
                  - name: x-hardware-test
                    exact_match: memory
                route:
                  cluster: webcluster1
                  metadata_match:
                    filter_metadata:
                      envoy.lb:
                        type: "bigmem"
                        stage: "prod"
              - match:
                  prefix: "/"
                route:
                  weighted_clusters:
                    clusters:
                    - name: webcluster1
                      weight: 90
                      metadata_match:
                        filter_metadata:
                          envoy.lb:
                            version: "1.0"
                    - name: webcluster1
                      weight: 10
                      metadata_match:
                        filter_metadata:
                          envoy.lb:
                            version: "1.1"
                  metadata_match:
                    filter_metadata:
                      envoy.lb:
                        stage: "prod"
          http_filters:
          - name: envoy.filters.http.router

  clusters:
  - name: webcluster1
    connect_timeout: 0.5s
    type: STRICT_DNS
    lb_policy: ROUND_ROBIN
    load_assignment:
      cluster_name: webcluster1
      endpoints:
      - lb_endpoints:
        - endpoint:
            address:
              socket_address:
                address: e1
                port_value: 80
          metadata:
            filter_metadata:
              envoy.lb:
                stage: "prod"
                version: "1.0"
                type: "std"
                xlarge: true
        - endpoint:
            address:
              socket_address:
                address: e2
                port_value: 80
          metadata:
            filter_metadata:
              envoy.lb:
                stage: "prod"
                version: "1.0"
                type: "std"
        - endpoint:
            address:
              socket_address:
                address: e3
                port_value: 80
          metadata:
            filter_metadata:
              envoy.lb:
                stage: "prod"
                version: "1.1"
                type: "std"
        - endpoint:
            address:
              socket_address:
                address: e4
                port_value: 80
          metadata:
            filter_metadata:
              envoy.lb:
                stage: "prod"
                version: "1.1"
                type: "std"
        - endpoint:
            address:
              socket_address:
                address: e5
                port_value: 80
          metadata:
            filter_metadata:
              envoy.lb:
                stage: "prod"
                version: "1.0"
                type: "bigmem"
        - endpoint:
            address:
              socket_address:
                address: e6
                port_value: 80
          metadata:
            filter_metadata:
              envoy.lb:
                stage: "prod"
                version: "1.1"
                type: "bigmem"
        - endpoint:
            address:
              socket_address:
                address: e7
                port_value: 80
          metadata:
            filter_metadata:
              envoy.lb:
                stage: "dev"
                version: "1.2-pre"
                type: "std"
    lb_subset_config:
      fallback_policy: DEFAULT_SUBSET            
      default_subset:
        stage: "prod"
        version: "1.0"
        type: "std"
      subset_selectors:
      - keys: ["stage", "type"]
      - keys: ["stage", "version"]
      - keys: ["version"]
      - keys: ["xlarge", "version"]
    health_checks:
    - timeout: 5s
      interval: 10s
      unhealthy_threshold: 2
      healthy_threshold: 1
      http_health_check:
        path: /livez
        expected_statuses:
          sroot@user:/opt/servicemesh_in_practise/Cluster-Manager/lb-subsets# cat admin  acce

 

root@user:/opt/servicemesh_in_practise/Cluster-Manager/lb-subsets# ./test.sh 172.31.33.2
Requests: v1.0:v1.1 = 179:21

 

root@user:/opt/servicemesh_in_practise/Cluster-Manager/lb-subsets# curl  -H "x-custom-version: pre-release" 172.31.33.2/hostname
ServerName: e7

 

root@user:/opt/servicemesh_in_practise/Cluster-Manager/lb-subsets# curl  -H "x-hardware-test: memory" 172.31.33.2/hostname
ServerName: e6