// Copyright 2019 The gRPC Authors
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

// This file contains the eds protocol and its dependency.
//
// TODO(juanlishen): This file is a hack to avoid a problem we're
// currently having where we can't depend on a proto file in an external
// repo due to bazel limitations.  Once that's fixed, this should be
// removed.  Until this, it should be used in the gRPC tests only, or else it
// will cause a conflict due to the same proto messages being defined in
// multiple files in the same binary.

syntax = "proto3";

package envoy.service.load_stats.v2;

import "google/protobuf/duration.proto";
import "src/proto/grpc/testing/xds/eds_for_test.proto";

// [#not-implemented-hide:] Not configuration. TBD how to doc proto APIs.
message EndpointLoadMetricStats {
  // Name of the metric; may be empty.
  string metric_name = 1;

  // Number of calls that finished and included this metric.
  uint64 num_requests_finished_with_metric = 2;

  // Sum of metric values across all calls that finished with this metric for
  // load_reporting_interval.
  double total_metric_value = 3;
}

message UpstreamLocalityStats {
  // Name of zone, region and optionally endpoint group these metrics were
  // collected from. Zone and region names could be empty if unknown.
  envoy.api.v2.Locality locality = 1;

  // The total number of requests successfully completed by the endpoints in the
  // locality.
  uint64 total_successful_requests = 2;

  // The total number of unfinished requests
  uint64 total_requests_in_progress = 3;

  // The total number of requests that failed due to errors at the endpoint,
  // aggregated over all endpoints in the locality.
  uint64 total_error_requests = 4;

  // The total number of requests that were issued by this Envoy since
  // the last report. This information is aggregated over all the
  // upstream endpoints in the locality.
  uint64 total_issued_requests = 8;

  // Stats for multi-dimensional load balancing.
  repeated EndpointLoadMetricStats load_metric_stats = 5;

//  // Endpoint granularity stats information for this locality. This information
//  // is populated if the Server requests it by setting
//  // :ref:`LoadStatsResponse.report_endpoint_granularity<envoy_api_field_load_stats.LoadStatsResponse.report_endpoint_granularity>`.
//  repeated UpstreamEndpointStats upstream_endpoint_stats = 7;

  // [#not-implemented-hide:] The priority of the endpoint group these metrics
  // were collected from.
  uint32 priority = 6;
}

// Per cluster load stats. Envoy reports these stats a management server in a
// :ref:`LoadStatsRequest<envoy_api_msg_load_stats.LoadStatsRequest>`
// [#not-implemented-hide:] Not configuration. TBD how to doc proto APIs.
// Next ID: 7
message ClusterStats {
  // The name of the cluster.
  string cluster_name = 1;

  // The eds_cluster_config service_name of the cluster.
  // It's possible that two clusters send the same service_name to EDS,
  // in that case, the management server is supposed to do aggregation on the load reports.
  string cluster_service_name = 6;

  // Need at least one.
  repeated UpstreamLocalityStats upstream_locality_stats = 2;

  // Cluster-level stats such as total_successful_requests may be computed by
  // summing upstream_locality_stats. In addition, below there are additional
  // cluster-wide stats.
  //
  // The total number of dropped requests. This covers requests
  // deliberately dropped by the drop_overload policy and circuit breaking.
  uint64 total_dropped_requests = 3;

  message DroppedRequests {
    // Identifier for the policy specifying the drop.
    string category = 1;
    // Total number of deliberately dropped requests for the category.
    uint64 dropped_count = 2;
  }
  // Information about deliberately dropped requests for each category specified
  // in the DropOverload policy.
  repeated DroppedRequests dropped_requests = 5;

  // Period over which the actual load report occurred. This will be guaranteed to include every
  // request reported. Due to system load and delays between the *LoadStatsRequest* sent from Envoy
  // and the *LoadStatsResponse* message sent from the management server, this may be longer than
  // the requested load reporting interval in the *LoadStatsResponse*.
  google.protobuf.Duration load_report_interval = 4;
}

// [#protodoc-title: Load reporting service]

service LoadReportingService {
  // 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.
  rpc StreamLoadStats(stream LoadStatsRequest) returns (stream LoadStatsResponse) {
  }
}

// A load report Envoy sends to the management server.
// [#not-implemented-hide:] Not configuration. TBD how to doc proto APIs.
message LoadStatsRequest {
  // Node identifier for Envoy instance.
  envoy.api.v2.Node node = 1;

  // A list of load stats to report.
  repeated ClusterStats cluster_stats = 2;
}

// 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.
message LoadStatsResponse {
  // Clusters to report stats for.
  repeated string clusters = 1;

  // 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.
  google.protobuf.Duration load_reporting_interval = 2;

  // Set to *true* if the management server supports endpoint granularity
  // report.
  bool report_endpoint_granularity = 3;
}
