// Copyright 2018 Istio 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.
syntax = "proto3";

import "google/api/field_behavior.proto";
import "google/protobuf/duration.proto";
import "networking/v1alpha3/virtual_service.proto";
import "gogoproto/gogo.proto";

// $title: Destination Rule
// $description: Configuration affecting load balancing, outlier detection, etc.
// $location: https://istio.io/docs/reference/config/networking/destination-rule.html
// $aliases: [/docs/reference/config/networking/v1alpha3/destination-rule]

// `DestinationRule` defines policies that apply to traffic intended for a
// service after routing has occurred. These rules specify configuration
// for load balancing, connection pool size from the sidecar, and outlier
// detection settings to detect and evict unhealthy hosts from the load
// balancing pool. For example, a simple load balancing policy for the
// ratings service would look as follows:
//
// ```yaml
// apiVersion: networking.istio.io/v1alpha3
// kind: DestinationRule
// metadata:
//   name: bookinfo-ratings
// spec:
//   host: ratings.prod.svc.cluster.local
//   trafficPolicy:
//     loadBalancer:
//       simple: LEAST_CONN
// ```
//
// Version specific policies can be specified by defining a named
// `subset` and overriding the settings specified at the service level. The
// following rule uses a round robin load balancing policy for all traffic
// going to a subset named testversion that is composed of endpoints (e.g.,
// pods) with labels (version:v3).
//
// ```yaml
// apiVersion: networking.istio.io/v1alpha3
// kind: DestinationRule
// metadata:
//   name: bookinfo-ratings
// spec:
//   host: ratings.prod.svc.cluster.local
//   trafficPolicy:
//     loadBalancer:
//       simple: LEAST_CONN
//   subsets:
//   - name: testversion
//     labels:
//       version: v3
//     trafficPolicy:
//       loadBalancer:
//         simple: ROUND_ROBIN
// ```
//
// **Note:** Policies specified for subsets will not take effect until
// a route rule explicitly sends traffic to this subset.
//
// Traffic policies can be customized to specific ports as well. The
// following rule uses the least connection load balancing policy for all
// traffic to port 80, while uses a round robin load balancing setting for
// traffic to the port 9080.
//
// ```yaml
// apiVersion: networking.istio.io/v1alpha3
// kind: DestinationRule
// metadata:
//   name: bookinfo-ratings-port
// spec:
//   host: ratings.prod.svc.cluster.local
//   trafficPolicy: # Apply to all ports
//     portLevelSettings:
//     - port:
//         number: 80
//       loadBalancer:
//         simple: LEAST_CONN
//     - port:
//         number: 9080
//       loadBalancer:
//         simple: ROUND_ROBIN
// ```
package istio.networking.v1alpha3;

option go_package = "istio.io/api/networking/v1alpha3";

// DestinationRule defines policies that apply to traffic intended for a service
// after routing has occurred.
//
// <!-- go code generation tags
// +kubetype-gen
// +kubetype-gen:groupVersion=networking.istio.io/v1alpha3
// +genclient
// +k8s:deepcopy-gen=true
// -->
message DestinationRule {
  // The name of a service from the service registry. Service
  // names are looked up from the platform's service registry (e.g.,
  // Kubernetes services, Consul services, etc.) and from the hosts
  // declared by [ServiceEntries](https://istio.io/docs/reference/config/networking/service-entry/#ServiceEntry). Rules defined for
  // services that do not exist in the service registry will be ignored.
  //
  // *Note for Kubernetes users*: When short names are used (e.g. "reviews"
  // instead of "reviews.default.svc.cluster.local"), Istio will interpret
  // the short name based on the namespace of the rule, not the service. A
  // rule in the "default" namespace containing a host "reviews" will be
  // interpreted as "reviews.default.svc.cluster.local", irrespective of
  // the actual namespace associated with the reviews service. _To avoid
  // potential misconfigurations, it is recommended to always use fully
  // qualified domain names over short names._
  //
  // Note that the host field applies to both HTTP and TCP services.
  string host = 1 [(google.api.field_behavior) = REQUIRED];

  // Traffic policies to apply (load balancing policy, connection pool
  // sizes, outlier detection).
  TrafficPolicy traffic_policy = 2;

  // One or more named sets that represent individual versions of a
  // service. Traffic policies can be overridden at subset level.
  repeated Subset subsets = 3;

  // A list of namespaces to which this destination rule is exported.
  // The resolution of a destination rule to apply to a service occurs in the
  // context of a hierarchy of namespaces. Exporting a destination rule allows
  // it to be included in the resolution hierarchy for services in
  // other namespaces. This feature provides a mechanism for service owners
  // and mesh administrators to control the visibility of destination rules
  // across namespace boundaries.
  //
  // If no namespaces are specified then the destination rule is exported to all
  // namespaces by default.
  //
  // The value "." is reserved and defines an export to the same namespace that
  // the destination rule is declared in. Similarly, the value "*" is reserved and
  // defines an export to all namespaces.
  //
  // NOTE: in the current release, the `exportTo` value is restricted to
  // "." or "*" (i.e., the current namespace or all namespaces).
  repeated string export_to = 4;
}

// Traffic policies to apply for a specific destination, across all
// destination ports. See DestinationRule for examples.
message TrafficPolicy {
  // Settings controlling the load balancer algorithms.
  LoadBalancerSettings load_balancer = 1;

  // Settings controlling the volume of connections to an upstream service
  ConnectionPoolSettings connection_pool = 2;

  // Settings controlling eviction of unhealthy hosts from the load balancing pool
  OutlierDetection outlier_detection = 3;

  // TLS related settings for connections to the upstream service.
  TLSSettings tls = 4;

  // Traffic policies that apply to specific ports of the service
  message PortTrafficPolicy {
    // Specifies the number of a port on the destination service
    // on which this policy is being applied.
    //
    PortSelector port = 1;

    // Settings controlling the load balancer algorithms.
    LoadBalancerSettings load_balancer = 2;

    // Settings controlling the volume of connections to an upstream service
    ConnectionPoolSettings connection_pool = 3;

    // Settings controlling eviction of unhealthy hosts from the load balancing pool
    OutlierDetection outlier_detection = 4;

    // TLS related settings for connections to the upstream service.
    TLSSettings tls = 5;
  }

  // Traffic policies specific to individual ports. Note that port level
  // settings will override the destination-level settings. Traffic
  // settings specified at the destination-level will not be inherited when
  // overridden by port-level settings, i.e. default values will be applied
  // to fields omitted in port-level traffic policies.
  repeated PortTrafficPolicy port_level_settings = 5;
}

// A subset of endpoints of a service. Subsets can be used for scenarios
// like A/B testing, or routing to a specific version of a service. Refer
// to [VirtualService](https://istio.io/docs/reference/config/networking/virtual-service/#VirtualService) documentation for examples of using
// subsets in these scenarios. In addition, traffic policies defined at the
// service-level can be overridden at a subset-level. The following rule
// uses a round robin load balancing policy for all traffic going to a
// subset named testversion that is composed of endpoints (e.g., pods) with
// labels (version:v3).
//
// ```yaml
// apiVersion: networking.istio.io/v1alpha3
// kind: DestinationRule
// metadata:
//   name: bookinfo-ratings
// spec:
//   host: ratings.prod.svc.cluster.local
//   trafficPolicy:
//     loadBalancer:
//       simple: LEAST_CONN
//   subsets:
//   - name: testversion
//     labels:
//       version: v3
//     trafficPolicy:
//       loadBalancer:
//         simple: ROUND_ROBIN
// ```
//
// **Note:** Policies specified for subsets will not take effect until
// a route rule explicitly sends traffic to this subset.
//
// One or more labels are typically required to identify the subset destination,
// however, when the corresponding DestinationRule represents a host that
// supports multiple SNI hosts (e.g., an egress gateway), a subset without labels
// may be meaningful. In this case a traffic policy with [TLSSettings](#TLSSettings)
// can be used to identify a specific SNI host corresponding to the named subset.
message Subset {
  // Name of the subset. The service name and the subset name can
  // be used for traffic splitting in a route rule.
  string name = 1 [(google.api.field_behavior) = REQUIRED];

  // Labels apply a filter over the endpoints of a service in the
  // service registry. See route rules for examples of usage.
  map<string, string> labels = 2;

  // Traffic policies that apply to this subset. Subsets inherit the
  // traffic policies specified at the DestinationRule level. Settings
  // specified at the subset level will override the corresponding settings
  // specified at the DestinationRule level.
  TrafficPolicy traffic_policy = 3;
}

// Load balancing policies to apply for a specific destination. See Envoy's
// load balancing
// [documentation](https://www.envoyproxy.io/docs/envoy/latest/intro/arch_overview/upstream/load_balancing/load_balancing)
// for more details.
//
// For example, the following rule uses a round robin load balancing policy
// for all traffic going to the ratings service.
//
// ```yaml
// apiVersion: networking.istio.io/v1alpha3
// kind: DestinationRule
// metadata:
//   name: bookinfo-ratings
// spec:
//   host: ratings.prod.svc.cluster.local
//   trafficPolicy:
//     loadBalancer:
//       simple: ROUND_ROBIN
// ```
//
// The following example sets up sticky sessions for the ratings service
// hashing-based load balancer for the same ratings service using the
// the User cookie as the hash key.
//
// ```yaml
//  apiVersion: networking.istio.io/v1alpha3
//  kind: DestinationRule
//  metadata:
//    name: bookinfo-ratings
//  spec:
//    host: ratings.prod.svc.cluster.local
//    trafficPolicy:
//      loadBalancer:
//        consistentHash:
//          httpCookie:
//            name: user
//            ttl: 0s
// ```
//
message LoadBalancerSettings {
  // Standard load balancing algorithms that require no tuning.
  enum SimpleLB {
    // Round Robin policy. Default
    ROUND_ROBIN = 0;

    // The least request load balancer uses an O(1) algorithm which selects
    // two random healthy hosts and picks the host which has fewer active
    // requests.
    LEAST_CONN = 1;

    // The random load balancer selects a random healthy host. The random
    // load balancer generally performs better than round robin if no health
    // checking policy is configured.
    RANDOM = 2;

    // This option will forward the connection to the original IP address
    // requested by the caller without doing any form of load
    // balancing. This option must be used with care. It is meant for
    // advanced use cases. Refer to Original Destination load balancer in
    // Envoy for further details.
    PASSTHROUGH = 3;
  };

  // Consistent Hash-based load balancing can be used to provide soft
  // session affinity based on HTTP headers, cookies or other
  // properties. This load balancing policy is applicable only for HTTP
  // connections. The affinity to a particular destination host will be
  // lost when one or more hosts are added/removed from the destination
  // service.
  message ConsistentHashLB {
    // Describes a HTTP cookie that will be used as the hash key for the
    // Consistent Hash load balancer. If the cookie is not present, it will
    // be generated.
    message HTTPCookie {
      // Name of the cookie.
      string name = 1 [(google.api.field_behavior) = REQUIRED];
      // Path to set for the cookie.
      string path = 2;
      // Lifetime of the cookie.
      google.protobuf.Duration ttl = 3 [(google.api.field_behavior) = REQUIRED, (gogoproto.stdduration) = true];
    };

    // The hash key to use.
    oneof hash_key {
      // Hash based on a specific HTTP header.
      string http_header_name = 1;

      // Hash based on HTTP cookie.
      HTTPCookie http_cookie = 2;

      // Hash based on the source IP address.
      bool use_source_ip = 3;
    };

    // The minimum number of virtual nodes to use for the hash
    // ring. Defaults to 1024. Larger ring sizes result in more granular
    // load distributions. If the number of hosts in the load balancing
    // pool is larger than the ring size, each host will be assigned a
    // single virtual node.
    uint64 minimum_ring_size = 4;
  };

  // (-- TODO: Enable Subset load balancing after moving to v2 API Also
  // look into enabling Priotity based load balancing for spilling over
  // from one priority pool to another. --)

  // Upstream load balancing policy.
  oneof lb_policy {
    SimpleLB simple = 1;
    ConsistentHashLB consistent_hash = 2;
  }
}

// Connection pool settings for an upstream host. The settings apply to
// each individual host in the upstream service.  See Envoy's [circuit
// breaker](https://www.envoyproxy.io/docs/envoy/latest/intro/arch_overview/upstream/circuit_breaking)
// for more details. Connection pool settings can be applied at the TCP
// level as well as at HTTP level.
//
// For example, the following rule sets a limit of 100 connections to redis
// service called myredissrv with a connect timeout of 30ms
//
// ```yaml
// apiVersion: networking.istio.io/v1alpha3
// kind: DestinationRule
// metadata:
//   name: bookinfo-redis
// spec:
//   host: myredissrv.prod.svc.cluster.local
//   trafficPolicy:
//     connectionPool:
//       tcp:
//         maxConnections: 100
//         connectTimeout: 30ms
//         tcpKeepalive:
//           time: 7200s
//           interval: 75s
// ```
message ConnectionPoolSettings {
  // Settings common to both HTTP and TCP upstream connections.
  message TCPSettings {
    // TCP keepalive.
    message TcpKeepalive {
      // Maximum number of keepalive probes to send without response before
      // deciding the connection is dead. Default is to use the OS level configuration
      // (unless overridden, Linux defaults to 9.)
      uint32 probes = 1;

      // The time duration a connection needs to be idle before keep-alive
      // probes start being sent. Default is to use the OS level configuration
      // (unless overridden, Linux defaults to 7200s (ie 2 hours.)
      google.protobuf.Duration time = 2;

      // The time duration between keep-alive probes.
      // Default is to use the OS level configuration
      // (unless overridden, Linux defaults to 75s.)
      google.protobuf.Duration interval = 3;
    };

    // Maximum number of HTTP1 /TCP connections to a destination host. Default 2^32-1.
    int32 max_connections = 1;

    // TCP connection timeout.
    google.protobuf.Duration connect_timeout = 2;

    // If set then set SO_KEEPALIVE on the socket to enable TCP Keepalives.
    TcpKeepalive tcp_keepalive = 3;
  };

  // Settings applicable to HTTP1.1/HTTP2/GRPC connections.
  message HTTPSettings {
    // Maximum number of pending HTTP requests to a destination. Default 2^32-1.
    int32 http1_max_pending_requests = 1;

    // Maximum number of requests to a backend. Default 2^32-1.
    int32 http2_max_requests = 2;

    // Maximum number of requests per connection to a backend. Setting this
    // parameter to 1 disables keep alive. Default 0, meaning "unlimited",
    // up to 2^29.
    int32 max_requests_per_connection = 3;

    // Maximum number of retries that can be outstanding to all hosts in a
    // cluster at a given time. Defaults to 2^32-1.
    int32 max_retries = 4;

    // The idle timeout for upstream connection pool connections. The idle timeout is defined as the period in which there are no active requests.
    // If not set, there is no idle timeout. When the idle timeout is reached the connection will be closed.
    // Note that request based timeouts mean that HTTP/2 PINGs will not keep the connection alive. Applies to both HTTP1.1 and HTTP2 connections.
    google.protobuf.Duration idle_timeout = 5;

    // Policy for upgrading http1.1 connections to http2.
    enum H2UpgradePolicy {
      // Use the global default.
      DEFAULT = 0;
      // Do not upgrade the connection to http2.
      // This opt-out option overrides the default.
      DO_NOT_UPGRADE = 1;
      // Upgrade the connection to http2.
      // This opt-in option overrides the default.
      UPGRADE = 2;
    };
    // Specify if http1.1 connection should be upgraded to http2 for the associated destination.
    H2UpgradePolicy h2_upgrade_policy = 6;
  };

  // Settings common to both HTTP and TCP upstream connections.
  TCPSettings tcp = 1;
  // HTTP connection pool settings.
  HTTPSettings http = 2;
}

// A Circuit breaker implementation that tracks the status of each
// individual host in the upstream service.  Applicable to both HTTP and
// TCP services.  For HTTP services, hosts that continually return 5xx
// errors for API calls are ejected from the pool for a pre-defined period
// of time. For TCP services, connection timeouts or connection
// failures to a given host counts as an error when measuring the
// consecutive errors metric. See Envoy's [outlier
// detection](https://www.envoyproxy.io/docs/envoy/latest/intro/arch_overview/upstream/outlier)
// for more details.
//
// The following rule sets a connection pool size of 100 HTTP1 connections
// with no more than 10 req/connection to the "reviews" service. In addition,
// it sets a limit of 1000 concurrent HTTP2 requests and configures upstream
// hosts to be scanned every 5 mins so that any host that fails 7 consecutive
// times with a 502, 503, or 504 error code will be ejected for 15 minutes.
//
// ```yaml
// apiVersion: networking.istio.io/v1alpha3
// kind: DestinationRule
// metadata:
//   name: reviews-cb-policy
// spec:
//   host: reviews.prod.svc.cluster.local
//   trafficPolicy:
//     connectionPool:
//       tcp:
//         maxConnections: 100
//       http:
//         http2MaxRequests: 1000
//         maxRequestsPerConnection: 10
//     outlierDetection:
//       consecutiveErrors: 7
//       interval: 5m
//       baseEjectionTime: 15m
// ```
message OutlierDetection {
  // Number of errors before a host is ejected from the connection
  // pool. Defaults to 5. When the upstream host is accessed over HTTP, a
  // 502, 503, or 504 return code qualifies as an error. When the upstream host
  // is accessed over an opaque TCP connection, connect timeouts and
  // connection error/failure events qualify as an error.
  int32 consecutive_errors = 1;

  // Time interval between ejection sweep analysis. format:
  // 1h/1m/1s/1ms. MUST BE >=1ms. Default is 10s.
  google.protobuf.Duration interval = 2;

  // Minimum ejection duration. A host will remain ejected for a period
  // equal to the product of minimum ejection duration and the number of
  // times the host has been ejected. This technique allows the system to
  // automatically increase the ejection period for unhealthy upstream
  // servers. format: 1h/1m/1s/1ms. MUST BE >=1ms. Default is 30s.
  google.protobuf.Duration base_ejection_time = 3;

  // Maximum % of hosts in the load balancing pool for the upstream
  // service that can be ejected. Defaults to 10%.
  int32 max_ejection_percent = 4;

  // Outlier detection will be enabled as long as the associated load balancing
  // pool has at least min_health_percent hosts in healthy mode. When the
  // percentage of healthy hosts in the load balancing pool drops below this
  // threshold, outlier detection will be disabled and the proxy will load balance
  // across all hosts in the pool (healthy and unhealthy). The threshold can be
  // disabled by setting it to 0%. The default is 0% as it's not typically
  // applicable in k8s environments with few pods per service.
  int32 min_health_percent = 5;
}

// SSL/TLS related settings for upstream connections. See Envoy's [TLS
// context](https://www.envoyproxy.io/docs/envoy/latest/api-v2/api/v2/auth/cert.proto.html)
// for more details. These settings are common to both HTTP and TCP upstreams.
//
// For example, the following rule configures a client to use mutual TLS
// for connections to upstream database cluster.
//
// ```yaml
// apiVersion: networking.istio.io/v1alpha3
// kind: DestinationRule
// metadata:
//   name: db-mtls
// spec:
//   host: mydbserver.prod.svc.cluster.local
//   trafficPolicy:
//     tls:
//       mode: MUTUAL
//       clientCertificate: /etc/certs/myclientcert.pem
//       privateKey: /etc/certs/client_private_key.pem
//       caCertificates: /etc/certs/rootcacerts.pem
// ```
//
// The following rule configures a client to use TLS when talking to a
// foreign service whose domain matches *.foo.com.
//
// ```yaml
// apiVersion: networking.istio.io/v1alpha3
// kind: DestinationRule
// metadata:
//   name: tls-foo
// spec:
//   host: "*.foo.com"
//   trafficPolicy:
//     tls:
//       mode: SIMPLE
// ```
//
// The following rule configures a client to use Istio mutual TLS when talking
// to rating services.
//
// ```yaml
// apiVersion: networking.istio.io/v1alpha3
// kind: DestinationRule
// metadata:
//   name: ratings-istio-mtls
// spec:
//   host: ratings.prod.svc.cluster.local
//   trafficPolicy:
//     tls:
//       mode: ISTIO_MUTUAL
// ```
message TLSSettings {
  // TLS connection mode
  enum TLSmode {
    // Do not setup a TLS connection to the upstream endpoint.
    DISABLE = 0;

    // Originate a TLS connection to the upstream endpoint.
    SIMPLE = 1;

    // Secure connections to the upstream using mutual TLS by presenting
    // client certificates for authentication.
    MUTUAL = 2;

    // Secure connections to the upstream using mutual TLS by presenting
    // client certificates for authentication.
    // Compared to Mutual mode, this mode uses certificates generated
    // automatically by Istio for mTLS authentication. When this mode is
    // used, all other fields in `TLSSettings` should be empty.
    ISTIO_MUTUAL = 3;
  };

  // Indicates whether connections to this port should be secured
  // using TLS. The value of this field determines how TLS is enforced.
  TLSmode mode = 1 [(google.api.field_behavior) = REQUIRED];

  // REQUIRED if mode is `MUTUAL`. The path to the file holding the
  // client-side TLS certificate to use.
  // Should be empty if mode is `ISTIO_MUTUAL`.
  string client_certificate = 2;

  // REQUIRED if mode is `MUTUAL`. The path to the file holding the
  // client's private key.
  // Should be empty if mode is `ISTIO_MUTUAL`.
  string private_key = 3;

  // OPTIONAL: The path to the file containing certificate authority
  // certificates to use in verifying a presented server certificate. If
  // omitted, the proxy will not verify the server's certificate.
  // Should be empty if mode is `ISTIO_MUTUAL`.
  string ca_certificates = 4;

  // A list of alternate names to verify the subject identity in the
  // certificate. If specified, the proxy will verify that the server
  // certificate's subject alt name matches one of the specified values.
  // If specified, this list overrides the value of subject_alt_names
  // from the ServiceEntry.
  repeated string subject_alt_names = 5;

  // SNI string to present to the server during TLS handshake.
  string sni = 6;
}
