warren build populates variables

cmd_build.go

@@ -5,23 +5,46 @@ import (
 	"log"
 	"os"
 	"os/exec"
+	"strings"
+	"time"
 )
 
+var buildUsage = `
+warren build - Runs go build and populates the following variables:
+
+  Build.GitBranch
+  Build.GitHash
+  Build.Date
+`
+
 var buildCmd = &Command{
 	Name:    "build",
 	Usage:   "",
 	Summary: "build the go server in the current directory",
-	Help:    `build extended help here...`,
+	Help:    buildUsage,
 	Run:     buildRun,
 }
 
 func buildRun(cmd *Command, args ...string) {
-	mycmd := exec.Command("go", "build", "-ldflags", fmt.Sprintf("-X main.Build.Date %s -X main.Build.GitHash %s -X main.Build.Num %d\"", "2014-12-08", "a1b2c3d4", 107))
-	fmt.Println(mycmd.Args)
-	fmt.Println(mycmd.Env)
-	mycmd.Stderr = os.Stderr
-	mycmd.Stdout = os.Stdout
-	err := mycmd.Run()
+	if len(args) > 0 && args[0] == "help" {
+		fmt.Print(cmd.Help)
+		return
+	}
+
+	githash, err := exec.Command("git", "rev-parse", "HEAD").Output()
+	if err != nil {
+		log.Fatal(err)
+	}
+	gitbranchb, err := exec.Command("git", "rev-parse", "--abbrev-ref", "HEAD").Output()
+	if err != nil {
+		log.Fatal(err)
+	}
+	gitbranch := strings.TrimSpace(string(gitbranchb))
+	date := time.Now().Format(time.RFC3339)
+	gobuild := exec.Command("go", "build", "-ldflags", fmt.Sprintf("-X main.Build.Date %s -X main.Build.GitHash %s -X main.Build.GitBranch %s\"", date, githash, gitbranch))
+	gobuild.Stderr = os.Stderr
+	gobuild.Stdout = os.Stdout
+	err = gobuild.Run()
 	if err != nil {
 		log.Fatal(err)
 	}