// Copyright 2020 The Monogon Project Authors.
//
// SPDX-License-Identifier: Apache-2.0
//
// 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";
package metropolis.proto.common;
option go_package = "source.monogon.dev/metropolis/proto/common";

// NodeRoles are the possible roles that a Metropolis Node should run within the
// cluster. These are configured by the cluster and can be retrieved through the
// Curator.
message NodeRoles {
    message KubernetesWorker {
    }
    KubernetesWorker kubernetes_worker = 1;
}

// NodeState is the state of a Metropolis node from the point of view of the
// cluster it is a part of (or intending to be a part of).
enum NodeState {
    NODE_STATE_INVALID = 0;

    // NEW: the node has established a first contact with the cluster and
    // intends to register into it. The node's identity has not been verified
    // and no hardware attestation of the new node was performed.
    // The node has generated a CUK/LUK and set up storage encrypted with the
    // combination of both keys.
    // The node has generated a private/public keypair, and that keypair has
    // been used to contact the already running Cluster.
    NODE_STATE_NEW = 1;
    // STANDBY: the node has successfully passed identity and hardware
    // attestation checks as defined by the cluster policy. The node still isn't
    // part of the cluster, as it itself might perform checks against the
    // running Cluster.
    NODE_STATE_STANDBY = 2;
    // UP: the node has passed all preconditions for STANDBY and has also
    // performed a commit into the cluster by exchanging its CUK for a
    // certificate issued by the cluster.
    // The node is now ready to serve, and its certificate can be used to
    // authenticate its identity cryptographically.
    NODE_STATE_UP = 3;
    // DISOWNED: the node has been rejected or decommissioned by the cluster.
    // Any further contact from the node to the cluster will be rejected.
    NODE_STATE_DISOWNED = 4;
};

// ClusterState is the state of the cluster from the point of view of a node.
// Different subsystems can watch this state and depend on it for behaviour
// (eg. start serving when HOME, maybe self-fence on SPLIT, etc.).
enum ClusterState {
    CLUSTER_STATE_INVALID = 0;

    // UNKNOWN: the node has not yet determined the existence of a cluster it
    // should join or start. This is a transient, initial state that should only
    // manifest during boot.
    CLUSTER_STATE_UNKNOWN = 1;
    // FOREIGN: the node is attempting to register into an already existing
    // cluster with which it managed to make preliminary contact, but which the
    // cluster has not yet fully productionized (eg. the node is still being
    // hardware attested, or the operator needs to confirm the
    // registration of this node).
    CLUSTER_STATE_FOREIGN = 2;
    // TRUSTED: the node is attempting to register into an already registered
    // cluster, and has been trusted by it. The node is now attempting to fully
    // commit to registering into the cluster.
    CLUSTER_STATE_TRUSTED = 3;
    // HOME: the node is part of this cluster. This is the bulk of time in which
    // this node will spend its time.
    CLUSTER_STATE_HOME = 4;
    // DISOWNING: the node has been disowned (ie., removed) by the cluster, and
    // that it will not be ever part of any cluster again, and  that it will be
    // decommissioned by the operator.
    CLUSTER_STATE_DISOWNING = 5;
    // SPLIT:the node would usually be Home in a cluster, but has been split
    // from the consensus of the cluster. This can happen for nodes running
    // consensus when consensus is lost (eg. when there is no quorum or this
    // node has been netsplit), and for other nodes if they have lost network
    // connectivity to the consensus nodes. Clients should make their own
    // decision what action to perform in this state, depending on the level of
    // consistency required and whether it makes sense for the node to fence its
    // services off.
    CLUSTER_STATE_SPLIT = 6;
}

// NodeStatus contains all fields self-reported by nodes. This data is
// inherently less trusted than other data available about a node, as it can be
// updated to any value by each node individually, including compromised nodes.
message NodeStatus {
    // external_address is the IP address that the node expects management,
    // cluster and user traffic to arrive at (ie. the address on which it is
    // listening for gRPC, and role-specific services like etcd and
    // Kubernetes).
    string external_address = 1;
}

// The Cluster Directory is information about the network addressing of nodes
// in a cluster. It is a serialized snapshot of some of the state within the
// etcd cluster, and can be used by external processes (like a node Registering
// into the cluster) to know how to reach this cluster over the network. It can
// be thought of as a phonebook, or a static name/address configuration that
// could live in /etc/hosts.
//
// The directory explicitly doesn't carry any information about the cluster's
// identity or security - these should be configured and checked by higher
// level configuration and processes. The directory can be stored and
// transmitted in cleartext and without an integrity checks (like saved to the
// EFI system partition across reboots) and any malicious change to it will
// cause no more than a denial of service against the consumer of this
// directory. This is because all nodes contacted must present a valid cluster
// identity/certificate before they are trusted by the consumers of this
// directory.
message ClusterDirectory {
    message Node {
        bytes public_key = 1;
        message Address {
            string host = 1;
        };
        repeated Address addresses = 2;
    };
    repeated Node nodes = 1;
}