Add deployment chain model

BUILD.bazel

@@ -57,6 +57,7 @@ genrule(
 # gazelle:exclude pkg/model/command.pb.validate.go
 # gazelle:exclude pkg/model/common.pb.validate.go
 # gazelle:exclude pkg/model/deployment.pb.validate.go
+# gazelle:exclude pkg/model/deployment_chain.pb.validate.go
 # gazelle:exclude pkg/model/environment.pb.validate.go
 # gazelle:exclude pkg/model/event.pb.validate.go
 # gazelle:exclude pkg/model/insight.pb.validate.go

pkg/model/BUILD.bazel

@@ -11,6 +11,7 @@ proto_library(
         "command.proto",
         "common.proto",
         "deployment.proto",
+        "deployment_chain.proto",
         "environment.proto",
         "event.proto",
         "insight.proto",

pkg/model/deployment_chain.proto

@@ -0,0 +1,48 @@
+// Copyright 2021 The PipeCD 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";
+
+package pipe.model;
+option go_package = "github.com/pipe-cd/pipe/pkg/model";
+
+import "validate/validate.proto";
+import "pkg/model/application.proto";
+import "pkg/model/common.proto";
+
+message DeploymentChain {
+    // The generated unique identifier.
+    string id = 1 [(validate.rules).string.min_len = 1];
+    // The ID of the project this environment belongs to.
+    string project_id = 2 [(validate.rules).string.min_len = 1];
+    // Deployment node contains all configuration required to perform deployment(s)
+    repeated DeploymentNode nodes = 3;
+    // Unix time when all the applications in this chain are deployed.
+    int64 completed_at = 100 [(validate.rules).int64.gte = 0];
+    // Unix time when the deployment chain is created.
+    int64 created_at = 101 [(validate.rules).int64.gt = 0];
+    // Unix time of the last time when the deployment chain is updated.
+    int64 updated_at = 102 [(validate.rules).int64.gt = 0];
+}
+
+message DeploymentNode {
+    // List of applications which should be deployed at the same time in chain.
+    repeated Application applications = 1;
+    // Control whether to start to deploy applications in this node or not.
+    bool runnable = 2;
+    // Unix time when the deployment chain node is started.
+    int64 started_at = 100 [(validate.rules).int64.gte = 0];
+    // Unix time when all the applications in this chain node are deployed.
+    int64 completed_at = 101 [(validate.rules).int64.gte = 0];
+}