syntax = "proto3";

import "api/base.proto";

import "google/protobuf/wrappers.proto";

message HealthCheck {
  // The time to wait for a health check response. If the timeout is reached the
  // health check attempt will be considered a failure.
  Duration timeout = 1;
  // The interval between health checks.
  Duration interval = 2;
  // An optional jitter amount in millseconds. If specified, during every
  // internal Envoy will add 0 to interval_jitter to the wait time.
  Duration interval_jitter = 3;

  // The number of unhealthy health checks required before a host is marked
  // unhealthy. Note that for http health checking if a host responds with 503
  // this threshold is ignored and the host is considered unhealthy immediately.
  google.protobuf.UInt32Value unhealthy_threshold = 4;
  // The number of healthy health checks required before a host is marked
  // healthy. Note that during startup, only a single successful health check is
  // required to mark a host healthy.
  google.protobuf.UInt32Value healthy_threshold = 5;

  // Non-serving port for health checking.
  google.protobuf.UInt32Value alt_port = 6;
  // Reuse health check connection between health checks. Default is true.
  google.protobuf.BoolValue reuse_connection = 7;

  // Describes the encoding of the payload bytes in the payload
  message Payload {
    oneof payload {
      google.protobuf.StringValue text = 1;
      google.protobuf.BytesValue binary = 2;
    }
  }
  message HttpHealthCheck {
    // The value of the host header in the HTTPS health check request. If left
    // empty (default value), the IP on behalf of which this health check is
    // performed will be used.
    string host = 1;
    // This parameter is required if the type is http. It species the HTTP path
    // that will be requested during health checking. For example /healthcheck.
    string path = 2;
    Payload send = 3;
    Payload receive = 4;
  }
  message TcpHealthCheck {
    // Empty payloads imply a connect-only health check.
    Payload send = 1;
    Payload receive = 2;
  }
  oneof health_checker {
    HttpHealthCheck http_health_check = 8;
    TcpHealthCheck tcp_health_check = 9;
  }
}

enum HealthStatus {
  // UNKNOWN should be treated by Envoy as HEALTHY.
  UNKNOWN = 0;
  HEALTHY = 1;
  UNHEALTHY = 2;
  // Connection draining in progress -
  // https://aws.amazon.com/blogs/aws/elb-connection-draining-remove-instances-from-service-with-care/
  // and
  // https://cloud.google.com/compute/docs/load-balancing/enabling-connection-draining.
  DRAINING = 3;
  // This value is used by HDS Remote server. From Envoy’s perspective
  // TIMEOUT = UNHEALTHY in case EDS returns HealthStatus.
  TIMEOUT = 4;
}