Add support for Delve

This adds support for debugging tool Delve. The command dlv starts a
debugging REPL that allows the user to debug his application using Delve
tool. Resolves #365.

cmd/commands/dlv/dlv.go

@@ -0,0 +1,109 @@
+// Copyright 2017 bee 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.
+
+// Package dlv ...
+package dlv
+
+import (
+	"flag"
+	"fmt"
+	"os/exec"
+
+	"github.com/beego/bee/cmd/commands"
+	"github.com/beego/bee/cmd/commands/version"
+	beeLogger "github.com/beego/bee/logger"
+	"github.com/derekparker/delve/pkg/terminal"
+	"github.com/derekparker/delve/service"
+	"github.com/derekparker/delve/service/rpc2"
+
+	dlvConfig "github.com/derekparker/delve/pkg/config"
+)
+
+var cmdDlv = &commands.Command{
+	CustomFlags: true,
+	UsageLine:   "dlv [-package=\"\"] [-port=8181]",
+	Short:       "Start a debugging session using Delve",
+	Long: `dlv command start a debugging session using debugging tool Delve.
+
+  To debug your application using Delve, use: {{"$ bee dlv" | bold}}
+
+  For more information on Delve: https://github.com/derekparker/delve
+`,
+	PreRun: func(cmd *commands.Command, args []string) { version.ShowShortVersionBanner() },
+	Run:    runDlv,
+}
+
+var (
+	packageName string
+	port        string
+)
+
+func init() {
+	fs := flag.NewFlagSet("dlv", flag.ContinueOnError)
+	fs.StringVar(&port, "port", "8181", "Port to listen to for clients")
+	fs.StringVar(&packageName, "package", "", "The package to debug (Must have a main package)")
+	cmdDlv.Flag = *fs
+	commands.AvailableCommands = append(commands.AvailableCommands, cmdDlv)
+}
+
+func runDlv(cmd *commands.Command, args []string) int {
+	if err := cmd.Flag.Parse(args); err != nil {
+		beeLogger.Log.Fatalf("Error parsing flags: %v", err.Error())
+	}
+	addr := fmt.Sprintf("127.0.0.1:%s", port)
+
+	startChan := make(chan bool)
+	defer close(startChan)
+
+	go runDelve(addr, startChan)
+
+	if started := <-startChan; started {
+		beeLogger.Log.Info("Starting Delve Debugger...")
+		status, err := startRepl(addr)
+		if err != nil {
+			beeLogger.Log.Fatal(err.Error())
+		}
+		return status
+	}
+	return 0
+}
+
+// runDelve runs the Delve debugger in API mode
+func runDelve(addr string, c chan bool) {
+	args := []string{
+		"debug",
+		"--headless",
+		"--accept-multiclient=true",
+		"--api-version=2",
+		fmt.Sprintf("--listen=%s", addr),
+	}
+	if err := exec.Command("dlv", args...).Start(); err == nil {
+		c <- true
+	}
+}
+
+// startRepl starts the Delve REPL
+func startRepl(addr string) (int, error) {
+	var client service.Client
+	client = rpc2.NewClient(addr)
+	term := terminal.New(client, dlvConfig.LoadConfig())
+
+	status, err := term.Run()
+	if err != nil {
+		return status, err
+	}
+	defer term.Close()
+
+	return 0, nil
+}