syntax = "proto3";

package envoy.api.v2;

import "api/address.proto";
import "api/base.proto";
import "api/health_check.proto";
import "api/protocol.proto";
import "api/tls_context.proto";

import "google/api/annotations.proto";
import "google/protobuf/duration.proto";
import "google/protobuf/wrappers.proto";

// Return list of all clusters this proxy will load balance to.
service ClusterDiscoveryService {
  rpc StreamClusters(stream DiscoveryRequest)
      returns (stream DiscoveryResponse) {
  }

  rpc FetchClusters(DiscoveryRequest)
      returns (DiscoveryResponse) {
    option (google.api.http) = {
      post: "/v2/discovery:clusters"
      body: "*"
    };
  }
}

// Circuit breaking settings can be specified individually for each defined
// priority.
message CircuitBreakers {
  message Thresholds {
    RoutingPriority priority = 1;
    // The maximum number of connections that Envoy will make to the upstream
    // cluster. If not specified, the default is 1024. See the circuit
    // breaking overview for more information.
    google.protobuf.UInt32Value max_connections = 2;
    // The maximum number of pending requests that Envoy will allow to the
    // upstream cluster. If not specified, the default is 1024. See the circuit
    // breaking overview for more information.
    google.protobuf.UInt32Value max_pending_requests = 3;
    // The maximum number of parallel requests that Envoy will make to the
    // upstream cluster. If not specified, the default is 1024. See the circuit
    // breaking overview for more information.
    google.protobuf.UInt32Value max_requests = 4;
    // The maximum number of parallel retries that Envoy will allow to the
    // upstream cluster. If not specified, the default is 3. See the circuit
    // breaking overview for more information.
    google.protobuf.UInt32Value max_retries = 5;
  }
  repeated Thresholds thresholds = 1;
}

message Cluster {
  // Supplies the name of the cluster which must be unique across all clusters.
  // The cluster name is used when emitting statistics. The cluster name can be
  // at most 60 characters long, and must not contain :.
  string name = 1;

  // The service discovery type to use for resolving the cluster.
  enum DiscoveryType {
    STATIC = 0;
    STRICT_DNS = 1;
    LOGICAL_DNS = 2;
    EDS = 3;
    ORIGINAL_DST = 4;
  }
  DiscoveryType type = 2;

  // Only valid when discovery type is EDS.
  message EdsClusterConfig {
    ConfigSource eds_config = 1;
    // Optional alternative to cluster name to present to EDS. This does not
    // have the same restrictions as cluster name, i.e. it may be arbritary
    // length and contain ':'.
    string service_name = 2;
  }
  EdsClusterConfig eds_cluster_config = 3;

  // The timeout for new network connections to hosts in the cluster.
  google.protobuf.Duration connect_timeout = 4;
  // Soft limit on size of the cluster’s connections read and write buffers. If
  // unspecified, an implementation defined default is applied (1MiB).
  google.protobuf.UInt32Value per_connection_buffer_limit_bytes = 5;

  // The load balancer type to use when picking a host in the cluster.
  enum LbPolicy {
    ROUND_ROBIN = 0;
    LEAST_REQUEST = 1;
    RING_HASH = 2;
    RANDOM = 3;
    ORIGINAL_DST_LB = 4;
  }
  LbPolicy lb_policy = 6;

  // If the service discovery type is static, static_hosts is required. If the
  // service discovery type is strict_dns or logical_dns, dns_hosts is required.
  oneof hosts_specifier {
    ResolvedAddresses static_hosts = 7;
    UnresolvedAddresses dns_hosts = 8;
  }

  // Optional active health checking configuration for the cluster. If no
  // configuration is specified no health checking will be done and all cluster
  // members will be considered healthy at all times.
  repeated HealthCheck health_checks = 9;

  // Optional maximum requests for a single upstream connection. This parameter
  // is respected by both the HTTP/1.1 and HTTP/2 connection pool
  // implementations. If not specified, there is no limit. Setting this
  // parameter to 1 will effectively disable keep alive.
  google.protobuf.UInt32Value max_requests_per_connection = 10;

  // Optional circuit breaking settings for the cluster.
  CircuitBreakers circuit_breakers = 11;

  // The TLS configuration for connections to the upstream cluster. If no TLS
  // configuration is specified, TLS will not be used for new connections.
  UpstreamTlsContext tls_context = 12;

  oneof protocol_options {
    TcpProtocolOptions tcp_protocol_options = 13;
    Http1ProtocolOptions http_protocol_options  = 14;
    // Even if default HTTP2 protocol options are desired, this field must be
    // set so that Envoy will assume that the upstream supports HTTP/2 when
    // making new HTTP connection pool connections. Currently, Envoy only
    // supports prior knowledge for upstream connections. Even if TLS is used
    // with ALPN, http2 must be specified. As an aside this allows HTTP/2
    // connections to happen over plain text.
    Http2ProtocolOptions http2_protocol_options  = 15;
    GrpcProtocolOptions grpc_protocol_options  = 16;
  }

  // If the dns refresh rate is specified and the cluster type is either
  // strict_dns, or logical_dns, this value is used as the cluster’s dns refresh
  // rate. If this setting is not specified, the value defaults to 5000. For
  // cluster types other than strict_dns and logical_dns this setting is
  // ignored.
  google.protobuf.Duration dns_refresh_rate = 17;

  // The DNS IP address resolution policy. The options are v4_only, v6_only, and
  // auto. If this setting is not specified, the value defaults to v4_only. When
  // v4_only is selected, the DNS resolver will only perform a lookup for
  // addresses in the IPv4 family. If v6_only is selected, the DNS resolver will
  // only perform a lookup for addresses in the IPv6 family. If auto is
  // specified, the DNS resolver will first perform a lookup for addresses in
  // the IPv6 family and fallback to a lookup for addresses in the IPv4 family.
  // For cluster types other than strict_dns and logical_dns, this setting is
  // ignored.
  enum DnsLookupFamily {
    AUTO = 0;
    V4_ONLY = 1;
    V6_ONLY = 2;
  }
  DnsLookupFamily dns_lookup_family = 18;

  // If DNS resolvers are specified and the cluster type is either strict_dns,
  // or logical_dns, this value is used to specify the cluster’s dns resolvers.
  // If this setting is not specified, the value defaults to the default
  // resolver, which uses /etc/resolv.conf for configuration. For cluster types
  // other than strict_dns and logical_dns this setting is ignored.
  ResolvedAddresses dns_resolvers = 19;

  // If specified, outlier detection will be enabled for this upstream cluster.
  message OutlierDetection {
    // The number of consecutive 5xx responses before a consecutive 5xx ejection
    // occurs. Defaults to 5.
    google.protobuf.UInt32Value consecutive_5xx = 1;
    // The time interval between ejection analysis sweeps. This can result in
    // both new ejections as well as hosts being returned to service. Defaults
    // to 10000ms or 10s.
    google.protobuf.Duration interval = 2;
    // The base time that a host is ejected for. The real time is equal to the
    // base time multiplied by the number of times the host has been ejected.
    // Defaults to 30000ms or 30s.
    google.protobuf.Duration base_ejection_time = 3;
    // The maximum % of an upstream cluster that can be ejected due to outlier
    // detection. Defaults to 10%.
    google.protobuf.UInt32Value max_ejection_percent = 4;
    // The % chance that a host will be actually ejected when an outlier status
    // is detected through consecutive 5xx. This setting can be used to disable
    // ejection or to ramp it up slowly. Defaults to 100.
    google.protobuf.UInt32Value enforcing_consecutive_5xx = 5;
    // The % chance that a host will be actually ejected when an outlier status
    // is detected through success rate statistics. This setting can be used to
    // disable ejection or to ramp it up slowly. Defaults to 100.
    google.protobuf.UInt32Value enforcing_success_rate = 6;
    // The number of hosts in a cluster that must have enough request volume to
    // detect success rate outliers. If the number of hosts is less than this
    // setting, outlier detection via success rate statistics is not performed
    // for any host in the cluster. Defaults to 5.
    google.protobuf.UInt32Value success_rate_minimum_hosts = 7;
    // The minimum number of total requests that must be collected in one
    // interval (as defined by the interval duration above) to include this host
    // in success rate based outlier detection. If the volume is lower than this
    // setting, outlier detection via success rate statistics is not performed
    // for that host. Defaults to 100.
    google.protobuf.UInt32Value success_rate_request_volume = 8;
    // This factor is used to determine the ejection threshold for success rate
    // outlier ejection. The ejection threshold is the difference between the
    // mean success rate, and the product of this factor and the standard
    // deviation of the mean success rate: mean - (stdev *
    // success_rate_stdev_factor). This factor is divided by a thousand to get a
    // double. That is, if the desired factor is 1.9, the runtime value should
    // be 1900. Defaults to 1900.
    google.protobuf.UInt32Value success_rate_stdev_factor = 9;
  }
  OutlierDetection outlier_detection = 20;

  // The interval for removing stale hosts from a cluster type
  // original_dst.  Hosts are considered stale if they have not been used
  // as upstream destinations during this interval.  New hosts are added
  // to original destination clusters on demand as new connections are
  // redirected to Envoy, causing the number of hosts in the cluster to
  // grow over time.  Hosts that are not stale (they are actively used as
  // destinations) are kept in the cluster, which allows connections to
  // them remain open, saving the latency that would otherwise be spent
  // on opening new connections.  If this setting is not specified, the
  // value defaults to 5000ms. For cluster types other than original_dst
  // this setting is ignored.
  google.protobuf.Duration cleanup_interval = 21;
}