rpc.proto

syntax = "proto3";
package etcdserverpb;

import "gogoproto/gogo.proto";
import "etcd/api/mvccpb/kv.proto";
import "etcd/api/authpb/auth.proto";
import "etcd/api/versionpb/version.proto";

// for grpc-gateway
import "google/api/annotations.proto";

option (gogoproto.marshaler_all) = true;
option (gogoproto.unmarshaler_all) = true;

service KV {
  // Range gets the keys in the range from the key-value store.
  rpc Range(RangeRequest) returns (RangeResponse) {
      option (google.api.http) = {
        post: "/v3/kv/range"
        body: "*"
    };
  }

  // Put puts the given key into the key-value store.
  // A put request increments the revision of the key-value store
  // and generates one event in the event history.
  rpc Put(PutRequest) returns (PutResponse) {
      option (google.api.http) = {
        post: "/v3/kv/put"
        body: "*"
    };
  }

  // DeleteRange deletes the given range from the key-value store.
  // A delete request increments the revision of the key-value store
  // and generates a delete event in the event history for every deleted key.
  rpc DeleteRange(DeleteRangeRequest) returns (DeleteRangeResponse) {
      option (google.api.http) = {
        post: "/v3/kv/deleterange"
        body: "*"
    };
  }

  // Txn processes multiple requests in a single transaction.
  // A txn request increments the revision of the key-value store
  // and generates events with the same revision for every completed request.
  // It is not allowed to modify the same key several times within one txn.
  rpc Txn(TxnRequest) returns (TxnResponse) {
      option (google.api.http) = {
        post: "/v3/kv/txn"
        body: "*"
    };
  }

  // Compact compacts the event history in the etcd key-value store. The key-value
  // store should be periodically compacted or the event history will continue to grow
  // indefinitely.
  rpc Compact(CompactionRequest) returns (CompactionResponse) {
      option (google.api.http) = {
        post: "/v3/kv/compaction"
        body: "*"
    };
  }
}

service Watch {
  // Watch watches for events happening or that have happened. Both input and output
  // are streams; the input stream is for creating and canceling watchers and the output
  // stream sends events. One watch RPC can watch on multiple key ranges, streaming events
  // for several watches at once. The entire event history can be watched starting from the
  // last compaction revision.
  rpc Watch(stream WatchRequest) returns (stream WatchResponse) {
      option (google.api.http) = {
        post: "/v3/watch"
        body: "*"
    };
  }
}

service Lease {
  // LeaseGrant creates a lease which expires if the server does not receive a keepAlive
  // within a given time to live period. All keys attached to the lease will be expired and
  // deleted if the lease expires. Each expired key generates a delete event in the event history.
  rpc LeaseGrant(LeaseGrantRequest) returns (LeaseGrantResponse) {
      option (google.api.http) = {
        post: "/v3/lease/grant"
        body: "*"
    };
  }

  // LeaseRevoke revokes a lease. All keys attached to the lease will expire and be deleted.
  rpc LeaseRevoke(LeaseRevokeRequest) returns (LeaseRevokeResponse) {
      option (google.api.http) = {
        post: "/v3/lease/revoke"
        body: "*"
        additional_bindings {
            post: "/v3/kv/lease/revoke"
            body: "*"
        }
    };
  }

  // LeaseKeepAlive keeps the lease alive by streaming keep alive requests from the client
  // to the server and streaming keep alive responses from the server to the client.
  rpc LeaseKeepAlive(stream LeaseKeepAliveRequest) returns (stream LeaseKeepAliveResponse) {
      option (google.api.http) = {
        post: "/v3/lease/keepalive"
        body: "*"
    };
  }

  // LeaseTimeToLive retrieves lease information.
  rpc LeaseTimeToLive(LeaseTimeToLiveRequest) returns (LeaseTimeToLiveResponse) {
      option (google.api.http) = {
        post: "/v3/lease/timetolive"
        body: "*"
        additional_bindings {
            post: "/v3/kv/lease/timetolive"
            body: "*"
        }
    };
  }

  // LeaseLeases lists all existing leases.
  rpc LeaseLeases(LeaseLeasesRequest) returns (LeaseLeasesResponse) {
      option (google.api.http) = {
        post: "/v3/lease/leases"
        body: "*"
        additional_bindings {
            post: "/v3/kv/lease/leases"
            body: "*"
        }
    };
  }
}

service Cluster {
  // MemberAdd adds a member into the cluster.
  rpc MemberAdd(MemberAddRequest) returns (MemberAddResponse) {
      option (google.api.http) = {
        post: "/v3/cluster/member/add"
        body: "*"
    };
  }

  // MemberRemove removes an existing member from the cluster.
  rpc MemberRemove(MemberRemoveRequest) returns (MemberRemoveResponse) {
      option (google.api.http) = {
        post: "/v3/cluster/member/remove"
        body: "*"
    };
  }

  // MemberUpdate updates the member configuration.
  rpc MemberUpdate(MemberUpdateRequest) returns (MemberUpdateResponse) {
      option (google.api.http) = {
        post: "/v3/cluster/member/update"
        body: "*"
    };
  }

  // MemberList lists all the members in the cluster.
  rpc MemberList(MemberListRequest) returns (MemberListResponse) {
      option (google.api.http) = {
        post: "/v3/cluster/member/list"
        body: "*"
    };
  }

  // MemberPromote promotes a member from raft learner (non-voting) to raft voting member.
  rpc MemberPromote(MemberPromoteRequest) returns (MemberPromoteResponse) {
      option (google.api.http) = {
        post: "/v3/cluster/member/promote"
        body: "*"
    };
  }
}

service Maintenance {
  // Alarm activates, deactivates, and queries alarms regarding cluster health.
  rpc Alarm(AlarmRequest) returns (AlarmResponse) {
      option (google.api.http) = {
        post: "/v3/maintenance/alarm"
        body: "*"
    };
  }

  // Status gets the status of the member.
  rpc Status(StatusRequest) returns (StatusResponse) {
      option (google.api.http) = {
        post: "/v3/maintenance/status"
        body: "*"
    };
  }

  // Defragment defragments a member's backend database to recover storage space.
  rpc Defragment(DefragmentRequest) returns (DefragmentResponse) {
      option (google.api.http) = {
        post: "/v3/maintenance/defragment"
        body: "*"
    };
  }

  // Hash computes the hash of whole backend keyspace,
  // including key, lease, and other buckets in storage.
  // This is designed for testing ONLY!
  // Do not rely on this in production with ongoing transactions,
  // since Hash operation does not hold MVCC locks.
  // Use "HashKV" API instead for "key" bucket consistency checks.
  rpc Hash(HashRequest) returns (HashResponse) {
      option (google.api.http) = {
        post: "/v3/maintenance/hash"
        body: "*"
    };
  }

  // HashKV computes the hash of all MVCC keys up to a given revision.
  // It only iterates "key" bucket in backend storage.
  rpc HashKV(HashKVRequest) returns (HashKVResponse) {
      option (google.api.http) = {
        post: "/v3/maintenance/hash"
        body: "*"
    };
  }

  // Snapshot sends a snapshot of the entire backend from a member over a stream to a client.
  rpc Snapshot(SnapshotRequest) returns (stream SnapshotResponse) {
      option (google.api.http) = {
        post: "/v3/maintenance/snapshot"
        body: "*"
    };
  }

  // MoveLeader requests current leader node to transfer its leadership to transferee.
  rpc MoveLeader(MoveLeaderRequest) returns (MoveLeaderResponse) {
      option (google.api.http) = {
        post: "/v3/maintenance/transfer-leadership"
        body: "*"
    };
  }

  // Downgrade requests downgrades, verifies feasibility or cancels downgrade
  // on the cluster version.
  // Supported since etcd 3.5.
  rpc Downgrade(DowngradeRequest) returns (DowngradeResponse) {
    option (google.api.http) = {
      post: "/v3/maintenance/downgrade"
      body: "*"
    };
  }
}

service Auth {
  // AuthEnable enables authentication.
  rpc AuthEnable(AuthEnableRequest) returns (AuthEnableResponse) {
      option (google.api.http) = {
        post: "/v3/auth/enable"
        body: "*"
    };
  }

  // AuthDisable disables authentication.
  rpc AuthDisable(AuthDisableRequest) returns (AuthDisableResponse) {
      option (google.api.http) = {
        post: "/v3/auth/disable"
        body: "*"
    };
  }

  // AuthStatus displays authentication status.
  rpc AuthStatus(AuthStatusRequest) returns (AuthStatusResponse) {
      option (google.api.http) = {
        post: "/v3/auth/status"
        body: "*"
    };
  }

  // Authenticate processes an authenticate request.
  rpc Authenticate(AuthenticateRequest) returns (AuthenticateResponse) {
      option (google.api.http) = {
        post: "/v3/auth/authenticate"
        body: "*"
    };
  }

  // UserAdd adds a new user. User name cannot be empty.
  rpc UserAdd(AuthUserAddRequest) returns (AuthUserAddResponse) {
      option (google.api.http) = {
        post: "/v3/auth/user/add"
        body: "*"
    };
  }

  // UserGet gets detailed user information.
  rpc UserGet(AuthUserGetRequest) returns (AuthUserGetResponse) {
      option (google.api.http) = {
        post: "/v3/auth/user/get"
        body: "*"
    };
  }

  // UserList gets a list of all users.
  rpc UserList(AuthUserListRequest) returns (AuthUserListResponse) {
      option (google.api.http) = {
        post: "/v3/auth/user/list"
        body: "*"
    };
  }

  // UserDelete deletes a specified user.
  rpc UserDelete(AuthUserDeleteRequest) returns (AuthUserDeleteResponse) {
      option (google.api.http) = {
        post: "/v3/auth/user/delete"
        body: "*"
    };
  }

  // UserChangePassword changes the password of a specified user.
  rpc UserChangePassword(AuthUserChangePasswordRequest) returns (AuthUserChangePasswordResponse) {
      option (google.api.http) = {
        post: "/v3/auth/user/changepw"
        body: "*"
    };
  }

  // UserGrant grants a role to a specified user.
  rpc UserGrantRole(AuthUserGrantRoleRequest) returns (AuthUserGrantRoleResponse) {
      option (google.api.http) = {
        post: "/v3/auth/user/grant"
        body: "*"
    };
  }

  // UserRevokeRole revokes a role of specified user.
  rpc UserRevokeRole(AuthUserRevokeRoleRequest) returns (AuthUserRevokeRoleResponse) {
      option (google.api.http) = {
        post: "/v3/auth/user/revoke"
        body: "*"
    };
  }

  // RoleAdd adds a new role. Role name cannot be empty.
  rpc RoleAdd(AuthRoleAddRequest) returns (AuthRoleAddResponse) {
      option (google.api.http) = {
        post: "/v3/auth/role/add"
        body: "*"
    };
  }

  // RoleGet gets detailed role information.
  rpc RoleGet(AuthRoleGetRequest) returns (AuthRoleGetResponse) {
      option (google.api.http) = {
        post: "/v3/auth/role/get"
        body: "*"
    };
  }

  // RoleList gets lists of all roles.
  rpc RoleList(AuthRoleListRequest) returns (AuthRoleListResponse) {
      option (google.api.http) = {
        post: "/v3/auth/role/list"
        body: "*"
    };
  }

  // RoleDelete deletes a specified role.
  rpc RoleDelete(AuthRoleDeleteRequest) returns (AuthRoleDeleteResponse) {
      option (google.api.http) = {
        post: "/v3/auth/role/delete"
        body: "*"
    };
  }

  // RoleGrantPermission grants a permission of a specified key or range to a specified role.
  rpc RoleGrantPermission(AuthRoleGrantPermissionRequest) returns (AuthRoleGrantPermissionResponse) {
      option (google.api.http) = {
        post: "/v3/auth/role/grant"
        body: "*"
    };
  }

  // RoleRevokePermission revokes a key or range permission of a specified role.
  rpc RoleRevokePermission(AuthRoleRevokePermissionRequest) returns (AuthRoleRevokePermissionResponse) {
      option (google.api.http) = {
        post: "/v3/auth/role/revoke"
        body: "*"
    };
  }
}

message ResponseHeader {
  option (versionpb.etcd_version_msg) = "3.0";

  // cluster_id is the ID of the cluster which sent the response.
  uint64 cluster_id = 1;
  // member_id is the ID of the member which sent the response.
  uint64 member_id = 2;
  // revision is the key-value store revision when the request was applied.
  // For watch progress responses, the header.revision indicates progress. All future events
  // received in this stream are guaranteed to have a higher revision number than the
  // header.revision number.
  int64 revision = 3;
  // raft_term is the raft term when the request was applied.
  uint64 raft_term = 4;
}

message RangeRequest {
  option (versionpb.etcd_version_msg) = "3.0";

  enum SortOrder {
    option (versionpb.etcd_version_enum) = "3.0";
    NONE = 0; // default, no sorting
    ASCEND = 1; // lowest target value first
    DESCEND = 2; // highest target value first
  }
  enum SortTarget {
    option (versionpb.etcd_version_enum) = "3.0";
    KEY = 0;
    VERSION = 1;
    CREATE = 2;
    MOD = 3;
    VALUE = 4;
  }

  // key is the first key for the range. If range_end is not given, the request only looks up key.
  bytes key = 1;
  // range_end is the upper bound on the requested range [key, range_end).
  // If range_end is '\0', the range is all keys >= key.
  // If range_end is key plus one (e.g., "aa"+1 == "ab", "a\xff"+1 == "b"),
  // then the range request gets all keys prefixed with key.
  // If both key and range_end are '\0', then the range request returns all keys.
  bytes range_end = 2;
  // limit is a limit on the number of keys returned for the request. When limit is set to 0,
  // it is treated as no limit.
  int64 limit = 3;
  // revision is the point-in-time of the key-value store to use for the range.
  // If revision is less or equal to zero, the range is over the newest key-value store.
  // If the revision has been compacted, ErrCompacted is returned as a response.
  int64 revision = 4;

  // sort_order is the order for returned sorted results.
  SortOrder sort_order = 5;

  // sort_target is the key-value field to use for sorting.
  SortTarget sort_target = 6;

  // serializable sets the range request to use serializable member-local reads.
  // Range requests are linearizable by default; linearizable requests have higher
  // latency and lower throughput than serializable requests but reflect the current
  // consensus of the cluster. For better performance, in exchange for possible stale reads,
  // a serializable range request is served locally without needing to reach consensus
  // with other nodes in the cluster.
  bool serializable = 7;

  // keys_only when set returns only the keys and not the values.
  bool keys_only = 8;

  // count_only when set returns only the count of the keys in the range.
  bool count_only = 9;

  // min_mod_revision is the lower bound for returned key mod revisions; all keys with
  // lesser mod revisions will be filtered away.
  int64 min_mod_revision = 10 [(versionpb.etcd_version_field)="3.1"];

  // max_mod_revision is the upper bound for returned key mod revisions; all keys with
  // greater mod revisions will be filtered away.
  int64 max_mod_revision = 11 [(versionpb.etcd_version_field)="3.1"];

  // min_create_revision is the lower bound for returned key create revisions; all keys with
  // lesser create revisions will be filtered away.
  int64 min_create_revision = 12 [(versionpb.etcd_version_field)="3.1"];

  // max_create_revision is the upper bound for returned key create revisions; all keys with
  // greater create revisions will be filtered away.
  int64 max_create_revision = 13 [(versionpb.etcd_version_field)="3.1"];
}

message RangeResponse {
  option (versionpb.etcd_version_msg) = "3.0";

  ResponseHeader header = 1;
  // kvs is the list of key-value pairs matched by the range request.
  // kvs is empty when count is requested.
  repeated mvccpb.KeyValue kvs = 2;
  // more indicates if there are more keys to return in the requested range.
  bool more = 3;
  // count is set to the number of keys within the range when requested.
  int64 count = 4;
}

message PutRequest {
  option (versionpb.etcd_version_msg) = "3.0";

  // key is the key, in bytes, to put into the key-value store.
  bytes key = 1;
  // value is the value, in bytes, to associate with the key in the key-value store.
  bytes value = 2;
  // lease is the lease ID to associate with the key in the key-value store. A lease
  // value of 0 indicates no lease.
  int64 lease = 3;

  // If prev_kv is set, etcd gets the previous key-value pair before changing it.
  // The previous key-value pair will be returned in the put response.
  bool prev_kv = 4 [(versionpb.etcd_version_field)="3.1"];

  // If ignore_value is set, etcd updates the key using its current value.
  // Returns an error if the key does not exist.
  bool ignore_value = 5 [(versionpb.etcd_version_field)="3.2"];

  // If ignore_lease is set, etcd updates the key using its current lease.
  // Returns an error if the key does not exist.
  bool ignore_lease = 6 [(versionpb.etcd_version_field)="3.2"];
}

message PutResponse {
  option (versionpb.etcd_version_msg) = "3.0";

  ResponseHeader header = 1;
  // if prev_kv is set in the request, the previous key-value pair will be returned.
  mvccpb.KeyValue prev_kv = 2 [(versionpb.etcd_version_field)="3.1"];
}

message DeleteRangeRequest {
  option (versionpb.etcd_version_msg) = "3.0";

  // key is the first key to delete in the range.
  bytes key = 1;
  // range_end is the key following the last key to delete for the range [key, range_end).
  // If range_end is not given, the range is defined to contain only the key argument.
  // If range_end is one bit larger than the given key, then the range is all the keys
  // with the prefix (the given key).
  // If range_end is '\0', the range is all keys greater than or equal to the key argument.
  bytes range_end = 2;

  // If prev_kv is set, etcd gets the previous key-value pairs before deleting it.
  // The previous key-value pairs will be returned in the delete response.
  bool prev_kv = 3 [(versionpb.etcd_version_field)="3.1"];
}

message DeleteRangeResponse {
  option (versionpb.etcd_version_msg) = "3.0";

  ResponseHeader header = 1;
  // deleted is the number of keys deleted by the delete range request.
  int64 deleted = 2;
  // if prev_kv is set in the request, the previous key-value pairs will be returned.
  repeated mvccpb.KeyValue prev_kvs = 3 [(versionpb.etcd_version_field)="3.1"];
}

message RequestOp {
  option (versionpb.etcd_version_msg) = "3.0";
  // request is a union of request types accepted by a transaction.
  oneof request {
    RangeRequest request_range = 1;
    PutRequest request_put = 2;
    DeleteRangeRequest request_delete_range = 3;
    TxnRequest request_txn = 4 [(versionpb.etcd_version_field)="3.3"];
  }
}

message ResponseOp {
  option (versionpb.etcd_version_msg) = "3.0";

  // response is a union of response types returned by a transaction.
  oneof response {
    RangeResponse response_range = 1;
    PutResponse response_put = 2;
    DeleteRangeResponse response_delete_range = 3;
    TxnResponse response_txn = 4 [(versionpb.etcd_version_field)="3.3"];
  }
}

message Compare {
  option (versionpb.etcd_version_msg) = "3.0";

  enum CompareResult {
    option (versionpb.etcd_version_enum) = "3.0";

    EQUAL = 0;
    GREATER = 1;
    LESS = 2;
    NOT_EQUAL = 3 [(versionpb.etcd_version_enum_value)="3.1"];
  }
  enum CompareTarget {
    option (versionpb.etcd_version_enum) = "3.0";

    VERSION = 0;
    CREATE = 1;
    MOD = 2;
    VALUE = 3;
    LEASE = 4 [(versionpb.etcd_version_enum_value)="3.3"];
  }
  // result is logical comparison operation for this comparison.
  CompareResult result = 1;
  // target is the key-value field to inspect for the comparison.
  CompareTarget target = 2;
  // key is the subject key for the comparison operation.
  bytes key = 3;
  oneof target_union {
    // version is the version of the given key
    int64 version = 4;
    // create_revision is the creation revision of the given key
    int64 create_revision = 5;
    // mod_revision is the last modified revision of the given key.
    int64 mod_revision = 6;
    // value is the value of the given key, in bytes.
    bytes value = 7;
    // lease is the lease id of the given key.
    int64 lease = 8 [(versionpb.etcd_version_field)="3.3"];
    // leave room for more target_union field tags, jump to 64
  }

  // range_end compares the given target to all keys in the range [key, range_end).
  // See RangeRequest for more details on key ranges.
  bytes range_end = 64 [(versionpb.etcd_version_field)="3.3"];
  // TODO: fill out with most of the rest of RangeRequest fields when needed.
}

// From google paxosdb paper:
// Our implementation hinges around a powerful primitive which we call MultiOp. All other database
// operations except for iteration are implemented as a single call to MultiOp. A MultiOp is applied atomically
// and consists of three components:
// 1. A list of tests called guard. Each test in guard checks a single entry in the database. It may check
// for the absence or presence of a value, or compare with a given value. Two different tests in the guard
// may apply to the same or different entries in the database. All tests in the guard are applied and
// MultiOp returns the results. If all tests are true, MultiOp executes t op (see item 2 below), otherwise
// it executes f op (see item 3 below).
// 2. A list of database operations called t op. Each operation in the list is either an insert, delete, or
// lookup operation, and applies to a single database entry. Two different operations in the list may apply
// to the same or different entries in the database. These operations are executed
// if guard evaluates to
// true.
// 3. A list of database operations called f op. Like t op, but executed if guard evaluates to false.
message TxnRequest {
  option (versionpb.etcd_version_msg) = "3.0";

  // compare is a list of predicates representing a conjunction of terms.
  // If the comparisons succeed, then the success requests will be processed in order,
  // and the response will contain their respective responses in order.
  // If the comparisons fail, then the failure requests will be processed in order,
  // and the response will contain their respective responses in order.
  repeated Compare compare = 1;
  // success is a list of requests which will be applied when compare evaluates to true.
  repeated RequestOp success = 2;
  // failure is a list of requests which will be applied when compare evaluates to false.
  repeated RequestOp failure = 3;
}

message TxnResponse {
  option (versionpb.etcd_version_msg) = "3.0";

  ResponseHeader header = 1;
  // succeeded is set to true if the compare evaluated to true or false otherwise.
  bool succeeded = 2;
  // responses is a list of responses corresponding to the results from applying
  // success if succeeded is true or failure if succeeded is false.
  repeated ResponseOp responses = 3;
}

// CompactionRequest compacts the key-value store up to a given revision. All superseded keys
// with a revision less than the compaction revision will be removed.
message CompactionRequest {
  option (versionpb.etcd_version_msg) = "3.0";

  // revision is the key-value store revision for the compaction operation.
  int64 revision = 1;
  // physical is set so the RPC will wait until the compaction is physically
  // applied to the local database such that compacted entries are totally
  // removed from the backend database.
  bool physical = 2;
}

message CompactionResponse {
  option (versionpb.etcd_version_msg) = "3.0";

  ResponseHeader header = 1;
}

message HashRequest {
  option (versionpb.etcd_version_msg) = "3.0";
}

message HashKVRequest {
  option (versionpb.etcd_version_msg) = "3.3";
  // revision is the key-value store revision for the hash operation.
  int64 revision = 1;
}

message HashKVResponse {
  option (versionpb.etcd_version_msg) = "3.3";

  ResponseHeader header = 1;
  // hash is the hash value computed from the responding member's MVCC keys up to a given revision.
  uint32 hash = 2;
  // compact_revision is the compacted revision of key-value store when hash begins.
  int64 compact_revision = 3;
}

message HashResponse {
  option (versionpb.etcd_version_msg) = "3.0";

  ResponseHeader header = 1;
  // hash is the hash value computed from the responding member's KV's backend.
  uint32 hash = 2;
}

message SnapshotRequest {
  option (versionpb.etcd_version_msg) = "3.3";
}

message SnapshotResponse {
  option (versionpb.etcd_version_msg) = "3.3";

  // header has the current key-value store information. The first header in the snapshot
  // stream indicates the point in time of the snapshot.
  ResponseHeader header = 1;

  // remaining_bytes is the number of blob bytes to be sent after this message
  uint64 remaining_bytes = 2;

  // blob contains the next chunk of the snapshot in the snapshot stream.
  bytes blob = 3;

  // local version of server that created the snapshot.
  // In cluster with binaries with different version, each cluster can return different result.
  // Informs which etcd server version should be used when restoring the snapshot.
  string version = 4 [(versionpb.etcd_version_field)="3.6"];
}

message WatchRequest {
  option (versionpb.etcd_version_msg) = "3.0";
  // request_union is a request to either create a new watcher or cancel an existing watcher.
  oneof request_union {
    WatchCreateRequest create_request = 1;
    WatchCancelRequest cancel_request = 2;
    WatchProgressRequest progress_request = 3 [(versionpb.etcd_version_field)="3.4"];
  }
}

message WatchCreateRequest {
  option (versionpb.etcd_version_msg) = "3.0";

  // key is the key to register for watching.
  bytes key = 1;

  // range_end is the end of the range [key, range_end) to watch. If range_end is not given,
  // only the key argument is watched. If range_end is equal to '\0', all keys greater than
  // or equal to the key argument are watched.
  // If the range_end is one bit larger than the given key,
  // then all keys with the prefix (the given key) will be watched.
  bytes range_end = 2;

  // start_revision is an optional revision to watch from (inclusive). No start_revision is "now".
  int64 start_revision = 3;

  // progress_notify is set so that the etcd server will periodically send a WatchResponse with
  // no events to the new watcher if there are no recent events. It is useful when clients
  // wish to recover a disconnected watcher starting from a recent known revision.
  // The etcd server may decide how often it will send notifications based on current load.
  bool progress_notify = 4;

  enum FilterType {
    option (versionpb.etcd_version_enum) = "3.1";

    // filter out put event.
    NOPUT = 0;
    // filter out delete event.
    NODELETE = 1;
  }

  // filters filter the events at server side before it sends back to the watcher.
  repeated FilterType filters = 5 [(versionpb.etcd_version_field)="3.1"];

  // If prev_kv is set, created watcher gets the previous KV before the event happens.
  // If the previous KV is already compacted, nothing will be returned.
  bool prev_kv = 6 [(versionpb.etcd_version_field)="3.1"];

  // If watch_id is provided and non-zero, it will be assigned to this watcher.
  // Since creating a watcher in etcd is not a synchronous operation,
  // this can be used ensure that ordering is correct when creating multiple
  // watchers on the same stream. Creating a watcher with an ID already in
  // use on the stream will cause an error to be returned.
  int64 watch_id = 7 [(versionpb.etcd_version_field)="3.4"];

  // fragment enables splitting large revisions into multiple watch responses.
  bool fragment = 8 [(versionpb.etcd_version_field)="3.4"];
}

message WatchCancelRequest {
  option (versionpb.etcd_version_msg) = "3.1";
  // watch_id is the watcher id to cancel so that no more events are transmitted.
  int64 watch_id = 1 [(versionpb.etcd_version_field)="3.1"];
}

// Requests the a watch stream progress status be sent in the watch response stream as soon as
// possible.
message WatchProgressRequest {
  option (versionpb.etcd_version_msg) = "3.4";
}

message WatchResponse {
  option (versionpb.etcd_version_msg) = "3.0";

  ResponseHeader header = 1;
  // watch_id is the ID of the watcher that corresponds to the response.
  int64 watch_id = 2;

  // created is set to true if the response is for a create watch request.
  // The client should record the watch_id and expect to receive events for
  // the created watcher from the same stream.
  // All events sent to the created watcher will attach with the same watch_id.
  bool created = 3;

  // canceled is set to true if the response is for a cancel watch request.
  // No further events will be sent to the canceled watcher.
  bool canceled = 4;

  // compact_revision is set to the minimum index if a watcher tries to watch
  // at a compacted index.
  //
  // This happens when creating a watcher at a compacted revision or the watcher cannot
  // catch up with the progress of the key-value store.
  //
  // The client should treat the watcher as canceled and should not try to create any
  // watcher with the same start_revision again.
  int64 compact_revision = 5;

  // cancel_reason indicates the reason for canceling the watcher.
  string cancel_reason = 6 [(versionpb.etcd_version_field)="3.4"];

  // framgment is true if large watch response was split over multiple responses.
  bool fragment = 7 [(versionpb.etcd_version_field)="3.4"];

  repeated mvccpb.Event events = 11;
}

message LeaseGrantRequest {
  option (versionpb.etcd_version_msg) = "3.0";

  // TTL is the advisory time-to-live in seconds. Expired lease will return -1.
  int64 TTL = 1;
  // ID is the requested ID for the lease. If ID is set to 0, the lessor chooses an ID.
  int64 ID = 2;
}

message LeaseGrantResponse {
  option (versionpb.etcd_version_msg) = "3.0";

  ResponseHeader header = 1;
  // ID is the lease ID for the granted lease.
  int64 ID = 2;
  // TTL is the server chosen lease time-to-live in seconds.
  int64 TTL = 3;
  string error = 4;
}

message LeaseRevokeRequest {
  option (versionpb.etcd_version_msg) = "3.0";

  // ID is the lease ID to revoke. When the ID is revoked, all associated keys will be deleted.
  int64 ID = 1;
}

message LeaseRevokeResponse {
  option (versionpb.etcd_version_msg) = "3.0";

  ResponseHeader header = 1;
}

message LeaseCheckpoint {
  option (versionpb.etcd_version_msg) = "3.4";

    // ID is the lease ID to checkpoint.
  int64 ID = 1;

  // Remaining_TTL is the remaining time until expiry of the lease.
  int64 remaining_TTL = 2;
}

message LeaseCheckpointRequest {
  option (versionpb.etcd_version_msg) = "3.4";

  repeated LeaseCheckpoint checkpoints = 1;
}

message LeaseCheckpointResponse {
  option (versionpb.etcd_version_msg) = "3.4";

  ResponseHeader header = 1;
}

message LeaseKeepAliveRequest {
  option (versionpb.etcd_version_msg) = "3.0";
  // ID is the lease ID for the lease to keep alive.
  int64 ID = 1;
}

message LeaseKeepAliveResponse {
  option (versionpb.etcd_version_msg) = "3.0";

  ResponseHeader header = 1;
  // ID is the lease ID from the keep alive request.
  int64 ID = 2;
  // TTL is the new time-to-live for the lease.
  int64 TTL = 3;
}

message LeaseTimeToLiveRequest {
  option (versionpb.etcd_version_msg) = "3.1";
  // ID is the lease ID for the lease.
  int64 ID = 1;
  // keys is true to query all the keys attached to this lease.
  bool keys = 2;
}

message LeaseTimeToLiveResponse {
  option (versionpb.etcd_version_msg) = "3.1";

  ResponseHeader header = 1;
  // ID is the lease ID from the keep alive request.
  int64 ID = 2;
  // TTL is the remaining TTL in seconds for the lease; the lease will expire in under TTL+1 seconds.
  int64 TTL = 3;
  // GrantedTTL is the initial granted time in seconds upon lease creation/renewal.
  int64 grantedTTL = 4;
  // Keys is the list of keys attached to this lease.
  repeated bytes keys = 5;
}

message LeaseLeasesRequest {
  option (versionpb.etcd_version_msg) = "3.3";
}

message LeaseStatus {
  option (versionpb.etcd_version_msg) = "3.3";

  int64 ID = 1;
  // TODO: int64 TTL = 2;
}

message LeaseLeasesResponse {
  option (versionpb.etcd_version_msg) = "3.3";

  ResponseHeader header = 1;
  repeated LeaseStatus leases = 2;
}

message Member {
  option (versionpb.etcd_version_msg) = "3.0";

  // ID is the member ID for this member.
  uint64 ID = 1;
  // name is the human-readable name of the member. If the member is not started, the name will be an empty string.
  string name = 2;
  // peerURLs is the list of URLs the member exposes to the cluster for communication.
  repeated string peerURLs = 3;
  // clientURLs is the list of URLs the member exposes to clients for communication. If the member is not started, clientURLs will be empty.
  repeated string clientURLs = 4;
  // isLearner indicates if the member is raft learner.
  bool isLearner = 5 [(versionpb.etcd_version_field)="3.4"];
}

message MemberAddRequest {
  option (versionpb.etcd_version_msg) = "3.0";

  // peerURLs is the list of URLs the added member will use to communicate with the cluster.
  repeated string peerURLs = 1;
  // isLearner indicates if the added member is raft learner.
  bool isLearner = 2 [(versionpb.etcd_version_field)="3.4"];
}

message MemberAddResponse {
  option (versionpb.etcd_version_msg) = "3.0";

  ResponseHeader header = 1;
  // member is the member information for the added member.
  Member member = 2;
  // members is a list of all members after adding the new member.
  repeated Member members = 3;
}

message MemberRemoveRequest {
  option (versionpb.etcd_version_msg) = "3.0";
  // ID is the member ID of the member to remove.
  uint64 ID = 1;
}

message MemberRemoveResponse {
  option (versionpb.etcd_version_msg) = "3.0";

  ResponseHeader header = 1;
  // members is a list of all members after removing the member.
  repeated Member members = 2;
}

message MemberUpdateRequest {
  option (versionpb.etcd_version_msg) = "3.0";

  // ID is the member ID of the member to update.
  uint64 ID = 1;
  // peerURLs is the new list of URLs the member will use to communicate with the cluster.
  repeated string peerURLs = 2;
}

message MemberUpdateResponse{
  option (versionpb.etcd_version_msg) = "3.0";

  ResponseHeader header = 1;
  // members is a list of all members after updating the member.
  repeated Member members = 2 [(versionpb.etcd_version_field)="3.1"];
}

message MemberListRequest {
  option (versionpb.etcd_version_msg) = "3.0";

  bool linearizable = 1 [(versionpb.etcd_version_field)="3.5"];
}

message MemberListResponse {
  option (versionpb.etcd_version_msg) = "3.0";

  ResponseHeader header = 1;
  // members is a list of all members associated with the cluster.
  repeated Member members = 2;
}

message MemberPromoteRequest {
  option (versionpb.etcd_version_msg) = "3.4";
  // ID is the member ID of the member to promote.
  uint64 ID = 1;
}

message MemberPromoteResponse {
  option (versionpb.etcd_version_msg) = "3.4";

  ResponseHeader header = 1;
  // members is a list of all members after promoting the member.
  repeated Member members = 2;
}

message DefragmentRequest {
  option (versionpb.etcd_version_msg) = "3.0";
}

message DefragmentResponse {
  option (versionpb.etcd_version_msg) = "3.0";

  ResponseHeader header = 1;
}

message MoveLeaderRequest {
  option (versionpb.etcd_version_msg) = "3.3";
  // targetID is the node ID for the new leader.
  uint64 targetID = 1;
}

message MoveLeaderResponse {
  option (versionpb.etcd_version_msg) = "3.3";

  ResponseHeader header = 1;
}

enum AlarmType {
  option (versionpb.etcd_version_enum) = "3.0";

	NONE = 0; // default, used to query if any alarm is active
	NOSPACE = 1; // space quota is exhausted
	CORRUPT = 2 [(versionpb.etcd_version_enum_value)="3.3"]; // kv store corruption detected
}

message AlarmRequest {
  option (versionpb.etcd_version_msg) = "3.0";

  enum AlarmAction {
    option (versionpb.etcd_version_enum) = "3.0";

    GET = 0;
    ACTIVATE = 1;
    DEACTIVATE = 2;
  }
  // action is the kind of alarm request to issue. The action
  // may GET alarm statuses, ACTIVATE an alarm, or DEACTIVATE a
  // raised alarm.
  AlarmAction action = 1;
  // memberID is the ID of the member associated with the alarm. If memberID is 0, the
  // alarm request covers all members.
  uint64 memberID = 2;
  // alarm is the type of alarm to consider for this request.
  AlarmType alarm = 3;
}

message AlarmMember {
  option (versionpb.etcd_version_msg) = "3.0";
  // memberID is the ID of the member associated with the raised alarm.
  uint64 memberID = 1;
  // alarm is the type of alarm which has been raised.
  AlarmType alarm = 2;
}

message AlarmResponse {
  option (versionpb.etcd_version_msg) = "3.0";

  ResponseHeader header = 1;
  // alarms is a list of alarms associated with the alarm request.
  repeated AlarmMember alarms = 2;
}

message DowngradeRequest {
  option (versionpb.etcd_version_msg) = "3.5";

  enum DowngradeAction {
    option (versionpb.etcd_version_enum) = "3.5";

    VALIDATE = 0;
    ENABLE = 1;
    CANCEL = 2;
  }

  // action is the kind of downgrade request to issue. The action may
  // VALIDATE the target version, DOWNGRADE the cluster version,
  // or CANCEL the current downgrading job.
  DowngradeAction action = 1;
  // version is the target version to downgrade.
  string version = 2;
}

message DowngradeResponse {
  option (versionpb.etcd_version_msg) = "3.5";

  ResponseHeader header = 1;
  // version is the current cluster version.
  string version = 2;
}

message StatusRequest {
  option (versionpb.etcd_version_msg) = "3.0";
}

message StatusResponse {
  option (versionpb.etcd_version_msg) = "3.0";

  ResponseHeader header = 1;
  // version is the cluster protocol version used by the responding member.
  string version = 2;
  // dbSize is the size of the backend database physically allocated, in bytes, of the responding member.
  int64 dbSize = 3;
  // leader is the member ID which the responding member believes is the current leader.
  uint64 leader = 4;
  // raftIndex is the current raft committed index of the responding member.
  uint64 raftIndex = 5;
  // raftTerm is the current raft term of the responding member.
  uint64 raftTerm = 6;
  // raftAppliedIndex is the current raft applied index of the responding member.
  uint64 raftAppliedIndex = 7 [(versionpb.etcd_version_field)="3.4"];
  // errors contains alarm/health information and status.
  repeated string errors = 8 [(versionpb.etcd_version_field)="3.4"];
  // dbSizeInUse is the size of the backend database logically in use, in bytes, of the responding member.
  int64 dbSizeInUse = 9 [(versionpb.etcd_version_field)="3.4"];
  // isLearner indicates if the member is raft learner.
  bool isLearner = 10 [(versionpb.etcd_version_field)="3.4"];
  // storageVersion is the version of the db file. It might be get updated with delay in relationship to the target cluster version.
  string storageVersion = 11 [(versionpb.etcd_version_field)="3.6"];
}

message AuthEnableRequest {
  option (versionpb.etcd_version_msg) = "3.0";
}

message AuthDisableRequest {
  option (versionpb.etcd_version_msg) = "3.0";
}

message AuthStatusRequest {
  option (versionpb.etcd_version_msg) = "3.5";
}

message AuthenticateRequest {
  option (versionpb.etcd_version_msg) = "3.0";

  string name = 1;
  string password = 2;
}

message AuthUserAddRequest {
  option (versionpb.etcd_version_msg) = "3.0";

  string name = 1;
  string password = 2;
  authpb.UserAddOptions options = 3 [(versionpb.etcd_version_field)="3.4"];
  string hashedPassword = 4 [(versionpb.etcd_version_field)="3.5"];
}

message AuthUserGetRequest {
  option (versionpb.etcd_version_msg) = "3.0";

  string name = 1;
}

message AuthUserDeleteRequest {
  option (versionpb.etcd_version_msg) = "3.0";
  // name is the name of the user to delete.
  string name = 1;
}

message AuthUserChangePasswordRequest {
  option (versionpb.etcd_version_msg) = "3.0";

  // name is the name of the user whose password is being changed.
  string name = 1;
  // password is the new password for the user. Note that this field will be removed in the API layer.
  string password = 2;
  // hashedPassword is the new password for the user. Note that this field will be initialized in the API layer.
  string hashedPassword = 3 [(versionpb.etcd_version_field)="3.5"];
}

message AuthUserGrantRoleRequest {
  option (versionpb.etcd_version_msg) = "3.0";

  // user is the name of the user which should be granted a given role.
  string user = 1;
  // role is the name of the role to grant to the user.
  string role = 2;
}

message AuthUserRevokeRoleRequest {
  option (versionpb.etcd_version_msg) = "3.0";

  string name = 1;
  string role = 2;
}

message AuthRoleAddRequest {
  option (versionpb.etcd_version_msg) = "3.0";

  // name is the name of the role to add to the authentication system.
  string name = 1;
}

message AuthRoleGetRequest {
  option (versionpb.etcd_version_msg) = "3.0";

  string role = 1;
}

message AuthUserListRequest {
  option (versionpb.etcd_version_msg) = "3.0";
}

message AuthRoleListRequest {
  option (versionpb.etcd_version_msg) = "3.0";
}

message AuthRoleDeleteRequest {
  option (versionpb.etcd_version_msg) = "3.0";

  string role = 1;
}

message AuthRoleGrantPermissionRequest {
  option (versionpb.etcd_version_msg) = "3.0";

  // name is the name of the role which will be granted the permission.
  string name = 1;
  // perm is the permission to grant to the role.
  authpb.Permission perm = 2;
}

message AuthRoleRevokePermissionRequest {
  option (versionpb.etcd_version_msg) = "3.0";

  string role = 1;
  bytes key = 2;
  bytes range_end = 3;
}

message AuthEnableResponse {
  option (versionpb.etcd_version_msg) = "3.0";

  ResponseHeader header = 1;
}

message AuthDisableResponse {
  option (versionpb.etcd_version_msg) = "3.0";

  ResponseHeader header = 1;
}

message AuthStatusResponse {
  option (versionpb.etcd_version_msg) = "3.5";

  ResponseHeader header = 1;
  bool enabled = 2;
  // authRevision is the current revision of auth store
  uint64 authRevision = 3;
}

message AuthenticateResponse {
  option (versionpb.etcd_version_msg) = "3.0";

  ResponseHeader header = 1;
  // token is an authorized token that can be used in succeeding RPCs
  string token = 2;
}

message AuthUserAddResponse {
  option (versionpb.etcd_version_msg) = "3.0";

  ResponseHeader header = 1;
}

message AuthUserGetResponse {
  option (versionpb.etcd_version_msg) = "3.0";

  ResponseHeader header = 1;

  repeated string roles = 2;
}

message AuthUserDeleteResponse {
  option (versionpb.etcd_version_msg) = "3.0";

  ResponseHeader header = 1;
}

message AuthUserChangePasswordResponse {
  option (versionpb.etcd_version_msg) = "3.0";

  ResponseHeader header = 1;
}

message AuthUserGrantRoleResponse {
  option (versionpb.etcd_version_msg) = "3.0";

  ResponseHeader header = 1;
}

message AuthUserRevokeRoleResponse {
  option (versionpb.etcd_version_msg) = "3.0";

  ResponseHeader header = 1;
}

message AuthRoleAddResponse {
  option (versionpb.etcd_version_msg) = "3.0";

  ResponseHeader header = 1;
}

message AuthRoleGetResponse {
  ResponseHeader header = 1 [(versionpb.etcd_version_field)="3.0"];

  repeated authpb.Permission perm = 2 [(versionpb.etcd_version_field)="3.0"];
}

message AuthRoleListResponse {
  option (versionpb.etcd_version_msg) = "3.0";

  ResponseHeader header = 1;

  repeated string roles = 2;
}

message AuthUserListResponse {
  option (versionpb.etcd_version_msg) = "3.0";

  ResponseHeader header = 1;

  repeated string users = 2;
}

message AuthRoleDeleteResponse {
  option (versionpb.etcd_version_msg) = "3.0";

  ResponseHeader header = 1;
}

message AuthRoleGrantPermissionResponse {
  option (versionpb.etcd_version_msg) = "3.0";

  ResponseHeader header = 1;
}

message AuthRoleRevokePermissionResponse {
  option (versionpb.etcd_version_msg) = "3.0";

  ResponseHeader header = 1;
}