cmd/relui: add proto definition for workflows

Using configuration for our workflows will help separate concerns
between implementation and workflow configuration.

Eventually, similar tasks can be re-used in different workflows, such as
fetching from Git, updating the VERSION file, or publishing a tag.

The current configuration definition is mainly illustrative, and is
expected to change as we build out a prototype.

For golang/go#40279

Change-Id: I5c6f8a18571ab819de0b1d026c86050735efeed9
Reviewed-on: https://go-review.googlesource.com/c/build/+/243340
Run-TryBot: Alexander Rakoczy <[email protected]>
TryBot-Result: Gobot Gobot <[email protected]>
Reviewed-by: Andrew Bonventre <[email protected]>

cmd/relui/main.go

@@ -5,13 +5,18 @@
 package main
 
 import (
+	"io/ioutil"
 	"log"
 	"net/http"
 	"os"
+	"path/filepath"
+
+	"github.com/golang/protobuf/proto"
+	reluipb "golang.org/x/build/cmd/relui/protos"
 )
 
 func main() {
-	s := &server{store: &memoryStore{}}
+	s := &server{store: &memoryStore{}, configs: loadWorkflowConfig("./workflows")}
 	http.Handle("/workflows/create", http.HandlerFunc(s.createWorkflowHandler))
 	http.Handle("/workflows/new", http.HandlerFunc(s.newWorkflowHandler))
 	http.Handle("/", fileServerHandler(relativeFile("./static"), http.HandlerFunc(s.homeHandler)))
@@ -23,3 +28,28 @@ func main() {
 	log.Printf("Listening on :" + port)
 	log.Fatal(http.ListenAndServe(":"+port, http.DefaultServeMux))
 }
+
+// loadWorkflowConfig loads Workflow configuration files from dir. It expects all files to be in textproto format.
+func loadWorkflowConfig(dir string) []*reluipb.Workflow {
+	fs, err := filepath.Glob(filepath.Join(relativeFile(dir), "*.textpb"))
+	if err != nil {
+		log.Fatalf("Error perusing %q for configuration", filepath.Join(dir, "*.textpb"))
+	}
+	if len(fs) == 0 {
+		log.Println("No workflow configuration found.")
+	}
+	var ws []*reluipb.Workflow
+	for _, f := range fs {
+		b, err := ioutil.ReadFile(f)
+		if err != nil {
+			log.Printf("ioutil.ReadFile(%q) = _, %v, wanted no error", f, err)
+		}
+		w := new(reluipb.Workflow)
+		if err = proto.UnmarshalText(string(b), w); err != nil {
+			log.Printf("Error unmarshalling Workflow from %q: %v", f, err)
+			continue
+		}
+		ws = append(ws, w)
+	}
+	return ws
+}

cmd/relui/protos/protos.go

@@ -0,0 +1,11 @@
+// Copyright 2020 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+package protos
+
+// Run "go generate" in this directory to update. You need to have:
+//
+// - a protoc binary (see https://github.com/golang/protobuf#installation)
+// - go get -u github.com/golang/protobuf/protoc-gen-go
+
+//go:generate protoc --proto_path=$GOPATH/src:. --go_out=plugins=grpc:. relui.proto

cmd/relui/protos/relui.proto

@@ -0,0 +1,53 @@
+// Copyright 2020 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+syntax = "proto3";
+
+package protos;
+
+message Workflow {
+  // name is a unique name for a workflow, such as local_go_release. The name must be unique across
+  // all workflow configurations.
+  string name = 1;
+
+  // buildable_asks is a list of tasks to be performed by the workflow.
+  repeated BuildableTask buildable_tasks = 2;
+
+  // params are parameters provided when creating a workflow.
+  map<string, string> params = 3;
+}
+
+message BuildableTask {
+  // name is a unique name for a task, such as fetch_go_source. The name must be unique across
+  // all workflow configurations.
+  string name = 1;
+
+  // depends_on is the name of a task this task depends on. Artifacts from the depends_on task will be available
+  // to this task.
+  string depends_on = 2;
+
+  // task_status is the current status of a task.
+  TaskStatus status = 3;
+
+  // artifact_url is an optional URL to an artifact published by this task.
+  string artifact_url = 4;
+
+  // git_source is an optional configuration for which git source to fetch.
+  GitSource git_source = 5;
+
+  // task_type is a unique type for a task, such as FetchGerritSource. Types are used by task runners to identify
+  // how to execute a task.
+  string task_type = 6;
+}
+
+message GitSource {
+  string url = 1;
+  string ref = 2;
+}
+
+enum TaskStatus {
+  TASK_STATUS_UNKNOWN = 0;
+  TASK_STATUS_CREATED = 1;
+  TASK_STATUS_STARTED = 2;
+}