feat(version): retrieve version and build date from VCS if unset

cmd/relspec/root.go

@@ -2,6 +2,8 @@ package main
 
 import (
 	"fmt"
+	"runtime/debug"
+	"time"
 
 	"github.com/spf13/cobra"
 )
@@ -12,6 +14,36 @@ var (
 	buildDate = "unknown"
 )
 
+func init() {
+	// If version wasn't set via ldflags, try to get it from build info
+	if version == "dev" {
+		if info, ok := debug.ReadBuildInfo(); ok {
+			// Try to get version from VCS
+			var vcsRevision, vcsTime string
+			for _, setting := range info.Settings {
+				switch setting.Key {
+				case "vcs.revision":
+					if len(setting.Value) >= 7 {
+						vcsRevision = setting.Value[:7]
+					}
+				case "vcs.time":
+					vcsTime = setting.Value
+				}
+			}
+
+			if vcsRevision != "" {
+				version = vcsRevision
+			}
+
+			if vcsTime != "" {
+				if t, err := time.Parse(time.RFC3339, vcsTime); err == nil {
+					buildDate = t.UTC().Format("2006-01-02 15:04:05 UTC")
+				}
+			}
+		}
+	}
+}
+
 var rootCmd = &cobra.Command{
 	Use:   "relspec",
 	Short: "RelSpec - Database schema conversion and analysis tool",