package envoy.service.load_stats.v2

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• rpc StreamLoadStats (stream LoadStatsRequest, stream LoadStatsResponse)

  lrs.proto:49

  Advanced API to allow for multi-dimensional load balancing by remote server. For receiving LB assignments, the steps are: 1, The management server is configured with per cluster/zone/load metric capacity configuration. The capacity configuration definition is outside of the scope of this document. 2. Envoy issues a standard {Stream,Fetch}Endpoints request for the clusters to balance. Independently, Envoy will initiate a StreamLoadStats bidi stream with a management server: 1. Once a connection establishes, the management server publishes a LoadStatsResponse for all clusters it is interested in learning load stats about. 2. For each cluster, Envoy load balances incoming traffic to upstream hosts based on per-zone weights and/or per-instance weights (if specified) based on intra-zone LbPolicy. This information comes from the above {Stream,Fetch}Endpoints. 3. When upstream hosts reply, they optionally add header <define header name> with ASCII representation of EndpointLoadMetricStats. 4. Envoy aggregates load reports over the period of time given to it in LoadStatsResponse.load_reporting_interval. This includes aggregation stats Envoy maintains by itself (total_requests, rpc_errors etc.) as well as load metrics from upstream hosts. 5. When the timer of load_reporting_interval expires, Envoy sends new LoadStatsRequest filled with load reports for each cluster. 6. The management server uses the load reports from all reported Envoys from around the world, computes global assignment and prepares traffic assignment destined for each zone Envoys are located in. Goto 2.

  message LoadStatsRequest

  lrs.proto:55

  A load report Envoy sends to the management server. [#not-implemented-hide:] Not configuration. TBD how to doc proto APIs.

  • optional api.v2.core.Node node = 1

    Node identifier for Envoy instance.

  • repeated api.v2.endpoint.ClusterStats cluster_stats = 2

    A list of load stats to report.

  message LoadStatsResponse

  lrs.proto:66

  The management server sends envoy a LoadStatsResponse with all clusters it is interested in learning load stats about. [#not-implemented-hide:] Not configuration. TBD how to doc proto APIs.

  • repeated string clusters = 1

    Clusters to report stats for. Not populated if *send_all_clusters* is true.

  • bool send_all_clusters = 4

    If true, the client should send all clusters it knows about. Only clients that advertise the "envoy.lrs.supports_send_all_clusters" capability in their :ref:`client_features<envoy_api_field_core.Node.client_features>` field will honor this field.

  • optional google.protobuf.Duration load_reporting_interval = 2

    The minimum interval of time to collect stats over. This is only a minimum for two reasons: 1. There may be some delay from when the timer fires until stats sampling occurs. 2. For clusters that were already feature in the previous *LoadStatsResponse*, any traffic that is observed in between the corresponding previous *LoadStatsRequest* and this *LoadStatsResponse* will also be accumulated and billed to the cluster. This avoids a period of inobservability that might otherwise exists between the messages. New clusters are not subject to this consideration.

  • bool report_endpoint_granularity = 3

    Set to *true* if the management server supports endpoint granularity report.