Adds comprehensive build versioning support to inject version information into all binaries at build time using ldflags

lib/flags/loadflags/api.go

@@ -5,9 +5,11 @@ import (
 )
 
 func LoadForCli(progName string) error {
+	registerVersionFlag(progName)
 	return loadForCli(progName)
 }
 
 func LoadForDaemon(progName string) error {
+	registerVersionFlag(progName)
 	return loadFlags(filepath.Join("/etc", progName))
 }

lib/flags/loadflags/impl.go

@@ -8,10 +8,24 @@ import (
 	"os"
 	"path/filepath"
 	"strings"
+
+	"github.com/Cloud-Foundations/Dominator/lib/version"
 )
 
 const systemDir = "/etc/config"
 
+func registerVersionFlag(name string) {
+	flag.BoolFunc("version", "Print version information and exit", func(string) error {
+		info := version.Get()
+		fmt.Printf("%s %s\n", name, info.Version)
+		fmt.Printf("  Commit: %s\n", info.GitCommit)
+		fmt.Printf("  Built:  %s\n", info.BuildDate)
+		fmt.Printf("  Go:     %s\n", info.GoVersion)
+		os.Exit(0)
+		return nil
+	})
+}
+
 func loadFlags(dirname string) error {
 	err := loadFlagsFromFile(filepath.Join(dirname, "flags.default"))
 	if err != nil {

lib/version/VERSION

@@ -0,0 +1 @@
+v0.12.0

lib/version/version.go

@@ -0,0 +1,77 @@
+package version
+
+import (
+	_ "embed"
+	"fmt"
+	"runtime"
+	"runtime/debug"
+	"strings"
+)
+
+//go:embed VERSION
+var baseVersion string
+
+type Info struct {
+	Version   string `json:"version"`
+	GitCommit string `json:"gitCommit"`
+	BuildDate string `json:"buildDate"`
+	GoVersion string `json:"goVersion"`
+	Dirty     bool   `json:"dirty"`
+}
+
+func Get() Info {
+	vcs := getVCSInfo()
+	version := strings.TrimSpace(baseVersion)
+	if vcs.revision != "unknown" {
+		version += "+" + vcs.revision
+	}
+	if vcs.dirty {
+		version += "-dirty"
+	}
+	return Info{
+		Version:   version,
+		GitCommit: vcs.revision,
+		BuildDate: vcs.buildTime,
+		GoVersion: runtime.Version(),
+		Dirty:     vcs.dirty,
+	}
+}
+
+func (i Info) String() string {
+	return fmt.Sprintf("%s (built: %s)", i.Version, i.BuildDate)
+}
+
+type vcsInfo struct {
+	revision  string
+	buildTime string
+	dirty     bool
+}
+
+func getVCSInfo() vcsInfo {
+	info := vcsInfo{
+		revision:  "unknown",
+		buildTime: "unknown",
+	}
+
+	buildInfo, ok := debug.ReadBuildInfo()
+	if !ok {
+		return info
+	}
+
+	for _, s := range buildInfo.Settings {
+		switch s.Key {
+		case "vcs.revision":
+			if len(s.Value) > 8 {
+				info.revision = s.Value[:8]
+			} else {
+				info.revision = s.Value
+			}
+		case "vcs.time":
+			info.buildTime = s.Value
+		case "vcs.modified":
+			info.dirty = s.Value == "true"
+		}
+	}
+
+	return info
+}