Add versioning

main.go

@@ -2,6 +2,7 @@ package main
 
 import (
 	"flag"
+	"fmt"
 	"os"
 
 	log "github.com/Sirupsen/logrus"
@@ -12,10 +13,21 @@ import (
 func main() {
 	const defaultConfigFile = "pipeline.yml"
 
-	var configFile string
+	var (
+		configFile string
+		version    bool
+	)
+
 	flag.StringVar(&configFile, "c", defaultConfigFile, "file which define pipeline")
+	flag.BoolVar(&version, "v", false, "print version string")
+
 	flag.Parse()
 
+	if version {
+		fmt.Println(OutputVersion())
+		os.Exit(0)
+	}
+
 	p, err := pipeline.LoadFromFile(configFile)
 	if err != nil {
 		log.Fatal(err)

version.go

@@ -0,0 +1,63 @@
+package main
+
+import (
+	"bytes"
+	"fmt"
+	"time"
+
+	log "github.com/Sirupsen/logrus"
+
+	latest "github.com/tcnksm/go-latest"
+)
+
+// Name is application name
+const Name = "walter"
+
+// Version is application version
+const Version string = "v2.0.0beta1"
+
+// GitCommit describes latest commit hash.
+// This is automatically extracted by git describe --always.
+var GitCommit string
+
+const defaultCheckTimeout = 2 * time.Second
+
+func OutputVersion() string {
+	var buf bytes.Buffer
+	fmt.Fprintf(&buf, "%s version %s", Name, Version)
+	if len(GitCommit) != 0 {
+		fmt.Fprintf(&buf, " (%s)", GitCommit)
+	}
+	fmt.Fprintf(&buf, "\n")
+
+	// Check latest version is release or not.
+	verCheckCh := make(chan *latest.CheckResponse)
+	go func() {
+		fixFunc := latest.DeleteFrontV()
+		githubTag := &latest.GithubTag{
+			Owner:             "walter-cd",
+			Repository:        "walter",
+			FixVersionStrFunc: fixFunc,
+		}
+
+		res, err := latest.Check(githubTag, fixFunc(Version))
+		if err != nil {
+			// Don't return error
+			log.Debugf("[ERROR] Check lastet version is failed: %s", err)
+			return
+		}
+		verCheckCh <- res
+	}()
+
+	select {
+	case <-time.After(defaultCheckTimeout):
+	case res := <-verCheckCh:
+		if res.Outdated {
+			fmt.Fprintf(&buf,
+				"Latest version of walter is v%s, please upgrade!\n",
+				res.Current)
+		}
+	}
+
+	return buf.String()
+}